There has been an interesting discussion thread on “Kaizen (Continuous Improvement) Experts” group on LinkedIn over the last few weeks on the differences between takt time and cycle time.
This is one of the fundamentals I’d have thought was well understood out there, along with some nuances, but I was quite surprised by the number (and “quality”) of misconceptions posted by people with “lean” and “Sigma” in their job titles.
I see two fundamental sources of confusion, and I would like to clarify each here.
“Cycle Time” has multiple definitions.
“Cycle time” can mean the total elapsed time between when a customer places an order and when he receives it. This definition can be used externally, or with internal customers. This definition actually pre-dates most of the English publications about the Toyota Production System.
It can also express the dock-to-dock flow time of the entire process, or some other linear segment of the flow. The value stream mapping in Learning to See calls this “production lead time” but some people call the same thing “cycle time.”
In early publications about the TPS, such as Suzaki’s New Manufacturing Challange and Hirano’s JIT Implementation Manual, the term “cycle time” is used to represent what, today, we call “takt time.” Just to confuse things more, “cycle time” is also used to represent the actual work cycle which may, or may not, be balanced to the takt time.
We also have machine cycle time, which is the start-to-start time of a machine and is used to balance to a manual work cycle and, in conjunction with the batch size, is a measure of its theoretical capacity.
“Cycle time” is used to express the total manual work involved in a process, or part of a process.
And, of course, “cycle time” is used to express the work cycle of a single person, not including end-of-cycle wait time.
None of these definitions is wrong. The source of confusion is when the users have not first been clear on their context. Therefore, it is critically important to establish context when you are talking. Adjectives like “operator cycle time” help. But the main thing is to be conscious that this can be a major source of confusion until you are certain you and the other person are on the same wavelength.
Takt time is often over simplified.
The classic calculation for takt time is:
Available Minutes for Production / Required Units of Production = Takt Time
This is exactly right. But people tend to get wrapped up around what constitutes “available time.” The “pure” definition is usually to take the total shift time(s) and subtract breaks, meetings, and other administrative non-working time. Nobody ever has a problem with this. (Maybe because that is the way Shingijutsu teaches it, and people tend to accept what Shingijutsu says at face value.)
So let’s review and example of what we have really done here. For the sake of a simple discussion, let’s assume a single 8 hour shift on a 5 day work week. There is a 1/2 hour unpaid lunch break in the middle of the day, so the workers are actually in the plant “at work” for 8 1/2 hours. (this is typical in the USA, if you are in another country, it might be different for you)
So we start with 8 hours:
8 hours x 60 minutes = 480 total minutes
But there is a 10 minute start-up process in the morning, two 10 minute breaks during the day, and 15 minutes shut-down and clean up at the end of the shift for a total of 45 minutes. This time is not production time, so it is subtracted from “available minutes”:
480 – 45 = 435
A very common mistake at this point would be to subtract the 30 minute lunch break. But notice that we did not include that time to start with. Subtracting it again would count it twice.
So when determining takt time, we would use 435 minutes as the baseline. If leveled customer demand was 50 units / day, then the takt time would be:
435 available minutes / 50 required units of production = 8.7 minutes (or 522 seconds)
Note that you can just as easily do this for a week, rather than a day.
435 minutes x 5 days = 2175 total available minutes
2175 available minutes / 250 required units of production still equals 8.7 minutes (or 522 seconds)
All of this is very basic stuff, and I would get few arguments up to this point, so why did I go through it?
Because if you were to run this factory at a 522 second takt time, you will come up short of your production targets. You will have to work overtime to make up the difference, or simply choose not to make it up.
Why? Because there are always problems, and problems disrupt production. Those disruptions come at the expense of the 435 minutes, and you end up with less production time than you calculated.
Then there is the fact that the plant manager called an all-hands safety meeting on Thursday. That pulled 30 minutes out of your production time. Almost four units of production lost there.
I could go on with a myriad of examples gathered from real production floors, but you get the idea.
Here is what is even worse, though.
When are you going to work on improvements?
If you expect operators to do their daily machine checks, when do you expect that to happen?
Do you truly expect your team members to “stop the line” when there is a problem?
All of these things take time away from production.
The consequence is that the shop floor leadership – the ones who have to deal with the consequences of disrupted production – will look at takt time as a nice theory, or a way to express a quota, but on a minute-by-minute level, it is pretty useless for actually pacing production.
All because it was oversimplified.
If you expect people to do something other than produce all day, you have to give them time to do it.
Let’s get back to the fundamental purpose of takt time and then see what makes sense.
The Purpose of Takt Time
Here is some heresy: Running to takt time is wholly unnecessary. Many factories operate just fine without even knowing what it is.
What those factories lose, however, is a fine-grained sense of how things are going minute by minute. Truthfully, if they have another way to immediately see disruptions, act to clear them, followed by solving the underlying problem then they are as “lean” as anyone. So here is the second heresy: You don’t NEED takt time to “be lean.”
What you need is some way to determine the minimum resource necessary to get the job done (JIT), and a way to continuously compare what is actually happening vs. what should be happening, and then a process to immediately act on any difference (jidoka). This is what makes “lean” happen.
Takt time is just a tool for doing this. It is, however, a very effective tool. It is so effective, in fact, that it is largely considered a necessary fundamental. Honestly, in day to day conversation, that is how I look at it. I made the above statements to get you to think outside the mantras for a minute.
What is takt time, really?
Takt time is an expression of your customer demand normalized and leveled over the time you choose to produce. It is not, and never has been, a pure customer demand signal. Customers do not order the same quantity every day. They do not stop ordering during your breaks, or when your shift is over. What takt time does, however, is make customer demand appear level across your working day.
This has several benefits.
First, is it makes capacity calculations really easy through a complex flow. You can easily determine what each and every process must be capable of. You can determine the necessary speeds of machines and other capital equipment. You determine minimum batch sizes when there are changeovers involved. You can look at any process and quickly determine the optimum number of people required to make it work, plus see opportunities where a little bit of kaizen will make a big difference in productivity.
More importantly, though, takt time gives your team members a way to know exactly what “success” looks like for each and every unit of production. (assuming you give them a way to compare every work cycle against the takt time – you do that, don’t you?)
This gives your team members the ability to let you know immediately if something is threatening required output. Put another way, it gives your entire team the ability to see quickly spot problems and respond to them before little issues accumulate into working on Saturday.
The key point here is that to get the benefit, you have to have a takt time that actually paces production. It has to be real, tangible, and practically applied on the shop floor. Otherwise it is just an abstract, theoretical number.
This means holding back “available time” for various planned (and unplanned) events where production would be stopped.
Further, in a complex flow, there may be local takt times – for example, a process that feeds more than one main line is going to be running to the aggregated demand, and so its takt will be faster than either of them. Likewise, a feeder line that builds up a part or option that is not used on every unit is going to be running slower.
And finally if disruptions do cause shortfalls to the required output, you have to make it up sometime. If you are constrained from running overtime (and many operations are for various reasons), then your only alternative is to build a slight over speed into your takt time calculation. The nuances of this are the topic of a much longer essay, but the basics are this:
– If everything goes well, you will finish early. Stop and use the time for organized improvement of either process or developing people. Continuing to produce is overproduction, and just means you run out of work sooner if you have a good day tomorrow.
– If there are issues, the use the buffer time for its intended purpose.
– If there are more issues than buffer time, there is an operational decision to make. Have a policy in place for this. The simplest is “hope for a better day tomorrow” and use tomorrow’s buffer time to close the gap. If this isn’t enough, then a management decision about overtime or some other remedy is required.
What about just allowing production to fall short? Well.. if this is OK, then you were running faster than customer demand already. So pull that “extra” out of your schedule, stop overproducing (which injects its own disruptions into things), and deal with what just actually have to accomplish. Stop inflating the numbers because they hide the problems, the problems accumulate, and you end up having to inflate even more.
Gee, all of this seems complicated.
Yeah, it can be. But that complexity is usually the result of having an ad-hoc culture that makes up the reactions as you go along rather than a comprehensive thought-out systems-level approach. The key is to work through the “what if…” for what you are doing and thinking about doing, how the pieces actually interconnect and interact, and have a plan.
That plan is the first part of Plan-Do-Check-Act.
Then, as the real world intrudes, you can test your thinking against reality and get better and better rather than just being glad you survived another day.
And that, is the whole point of knowing your cycle times and takt times.
The best (or ‘worst’, if you like) example of a misconception I have seen was a welding machine that allowed the operator to actually set the Takt Time…
In a demand constraint system, are the takt time endless cycle time The same?
Josh –
Takt time is purely an expression of demand. You can have a takt time without any production at all – it is demand you aren’t meeting.
Cycle time represents reality – what your system is actually doing. In Martin’s case, the operators weren’t really setting “takt time” they were adjusting “cycle time” – the rate of output.
What if you have a
To take into account for yield and approximately 20 different styles of parts
Matt –
Takt time is simply a normalization of your customer demand over a period of time.
The demand exists regardless of whether or not your are meeting that demand.
If you have yield issues, then your actual operating rate, sometimes called planned cycle time (in Toyota Kata) or operational takt time (which is differentiated from customer takt time) will have to be faster so that you can actually meet the demand. That, of course, means you need more production capacity to get a certain level of useable output, and that extra capacity is not free. How much of your day are you making things that end up in the scrap bin is always an interesting question to ask.
As for different styles of parts –
Any given production line has a finite amount of time to actually operate every day.
That time can be divided into smaller units, a fixed time pitch. For example, maybe we set a pitch of 15 minutes.
In each pitch we schedule 15 minutes worth of work, be that one part that takes 15 minutes to make, or 3 parts that take 5 minutes each.
The idea is that you have the ability to frequently check if things are running the way they should, so you can spot problems early and get out in front of them while they are small vs. finding out at the end of the day (or week, or month) that you are short.
hi, Using takt time the number of resources can be calculated. but how to optimize them in case of limited number of available resources.
Jyoti –
Reducing the resources necessary to produce value is the ultimate goal of kaizen.
The takt time / cycle time calculation tells you what you MUST have to do the job as it is currently done.
If you don’t like what the math tells you, then set a target objective (what cycle time do you NEED?) then apply kaizen / problem solving to hit that target.
good article….helped to understand the concept…Can you brief on throughput …
“Throughput” is more ambiguous than “cycle time.”
The Theory of Constraints community has a very specific definition, relating to the rate cash is generated through sales.
But outside of that, you really have to take it in context. In general, “throughput” relates to the output capacity of the system, or a part of the system.
When I am talking about capacity and constraints, I am generally looking at cycle times vs. the required operational takt (the actual rate we are striving to hit when things are running).
Hello,
I am facing a very big issue regarding takt time and cycle time. It would be really great if you could help me solve it. I am currently doing my Master thesis in a company and I am a bit confused with this takt time cycle time ratio.Well the scenario is like this. The company I am doing my thesis is a solar panel manufacturing company.There are 9 different processes involved with both manual station and machine. Each process has a different cycle time and at each process the number of input differs i.e, in the first process there is an input of 11 products which comes out after a specific processing time.At the next step ,which is a manual process, these products are worked on manually and are placed as a batch of four in the third process. Now the problem arises in the third process,where the cycle time is much greater than the takt time. Could you please help me with this situation. I am not able to get a clear picture.
Thanks,
Maria
Maria –
Let’s start with the takt time. That simply defines the one-by-one required rate that each process must deliver to its customer.
Deliver faster than the takt time, and you are using capacity (and spending money) wastefully.
Deliver slower than the takt time and the customer is not getting what they need.
This is over-simplified, but it is the foundational concept.
What you strive to achieve is the closest possible balance between cycle time and takt time. The closer that balance, the more efficient your production process.
Now, let’s look at situations where the cycle time is much longer than the takt time.
Let me use automobile manufacturing as an example.
If I look at the high-level process steps for assembling a car, they are:
Stamping
Welding
Painting
Assembly
The takt time on an automobile line is typically about 55 seconds.
Obviously it take longer than 55 seconds to assemble a car.
It actually takes about six hours.
So “assembly” as a process step is MUCH longer than the takt time, about 400 times longer.
So they break up “assembly” into small sub-steps, each taking a tiny bit less than 55 seconds.
Looking at your process #3, the question is: If they took in ONE item, and processed it all the way through, how long would it take?
Divide that time by the takt time.
The result is the number of stations or work zones, units of work-in-process, that are necessary in that process for them to make the takt time.
In other words, if the takt time is 5 minutes, and it takes 20 minutes to perform the process, they need to be working on four of them at once, each at different stages of the process.
They COULD also run batches of four, cycling one batch every 20 minutes, and that would make the output, but it introduces other problems into the flow that we want to try to eliminate.
If this isn’t clear enough, feel free to click on the “Contact Mark” link on the right sidebar. That sets you up to email me directly, and we can get specific about your situation.
Mark
hi,
can you help me hoe to calculate cycletime?
and what are the rating factor i can give.
and now i will calculate :
Standard time=(normal working time*rating factor*operator efficiency) normal working time is : stage wise process time and rating factor is iwll give 10% and operator efficiency is 80% this type i will callculate.
this correct. can give me the ratting factor details. and manual work how much efficiency i can give and then machine works means how much EFF i can give & welding workers how much EFF i can give please need to send me the details in my mail ID :
Replied by direct email about the difference between traditional industrial engineering calculations (with efficiency factors, etc) and the TPS approach.
Efficiency factors are really inefficiency factors. They are saying, in effect, that there are aspects of this process that we simply cannot understand, therefore we will lump them together and just accept them.
TPS takes the opposite approach. By rigidly specifying every detail of how the process should operate (PLAN), and then setting up built-in “CHECKS” that compare actual vs. intended, we surface the issues that we did not understand.
In other words, “Chatter is Signal.”
Ironically, we know that we will be wrong nearly every time. But only if we try to be as “right as we can” will we learn what we did not know.
hi,should the OEE be taken into account while calculating takt time???
like:: takt time =(available time*OEE)/demand
Arjun –
There are a couple of answers to your question.
When determining the overall takt time for the value stream – the customer takt time- no.
But realistically, if the machine is not operational 100% of the time, then you need to run it faster when it IS operational if you want to make the production numbers.
OEE has a number of components, some of them are planned down time (tools changes, changeovers, planned maintenance, etc) others are unplanned (slowdowns, stoppages, etc).
As you account for these factors, you subtracting from available time.
Just multiplying by OEE is the simplest solution, but this is like the issue with “efficiency factors” that I discussed in a previous comment on this topic.
What I suggest is breaking down the losses separately.
Planned maintenance time
Tool changes
Changeovers
Things like the above are planned, you know when they will happen.
I would account for their impact on production by subtracting a pro-rated factor from available time.
Note: I would discourage multiplying anything by a percentage. You need to know how much actual time you are taking away from production.
Then, of course, you also need to plan these activities and develop a way to work out how much time is ACTUALLY spent vs. how much time you planned on spending, and apply kaizen to these tasks. Any improvement goes straight to machine capacity.
Unplanned stoppages and slowdowns are a little trickier because you don’t know when they will happen.
And how you handle them realistically depends on how you are approaching maintenance.
A sadly high number of operations just use OEE as a blanket factor, but don’t have an active program to raise it (i.e. aggressive TPM).
They are the ones who just factor in the downtime and build the rest of their processes to accommodate it.
If you do have a good TPM program, then you set your system to run a little better than you CAN. You factor in some, but not all, of the problem(s).
That becomes your operational takt time (or your target cycle time). You have a “line stop” situation whenever your process exceeds this planned cycle time.
You respond to the problem, determine what caused it, fix it, eliminate the root cause, and try again.
If you do it that way, eventually you will be running smoothly at the planned time.
That is time to reduce your factor again, and flush out more problems.
Doing it this way assures you meet the overall takt time, gives you time to work on problems, and drives you to get better.
However it requires you to have good visual controls and know, at any time, the exact status of the equipment:
– Should it be running?
– Is it running?
– How fast should it be running?
– How fast is it running?
Hi,
Help me to calculate the cycle time and takt time for an assembly line and packing line where 10000 units will be assembled/8hrs with 20 members and the same 10000 units will be packed/8hrs with 30 members.
Also, help me how to reduce my takt time or speeding up my takt time. Pl send me the details to my mail ID.
Replied by email.
Key points:
This takt time is somewhat less than 3 seconds, which is really too fast for a single line if the work is mostly manual. You run the risk of repetitive motion injuries as well as other problems.
If the work is mostly automated, then I would suggest a “pitch” calculated around about 100 units of production to take the time into a more human scale.
You can establish a “target cycle time” but otherwise, cycle time must be measured in the actual operation.
The number of people required is calculated by total cycle time / takt time.
Sir I had a similar question of how to reduce takt time. Can reply me by mail
Hi Mark, thanks for ur reply on my query..
i need to know the difference between Efficiency and Productivity.
Outside of traditional industrial engineering / accounting factors, there really aren’t formal definitions for these terms.
“Productivity” is generally calculated as some form of Units of Output / Units of Resources Input, so you could have “units produced / person” for example.
“Efficiency” is generally some measure of the “resources actually used productively / total resources available”
Using either of these to measure people’s job performance is generally destructive to the goals of the organization.
It is better to use any measures as a way to determine how effective your improvements and problem solving activities are.
I am having an issue with both Takt Time and cycle Time if my Actual takt time is 16.9 seconds per unit and my daily goals are 1498, with just 3 operators how many units per minute should we be building as a finished product? I personally would like to see at least 5 per minute but some say that I might be pushing my employees to hard? Please help
The number of team members is not a factor in determining takt time.
If your takt time is 16.9 seconds, that works out to 3.6 units / minute of required production.
If you are building faster than that, you are overproducing.
I wanted to thank you for your extremely fast reply and also how exactly did you figure the 3.6 per minute? what is the actual calculation I should use for this?
Jason –
Dividing a minute by your takt time gives “takt times per minute.”
Since 1 takt time = one unit of production (by definition):
If the takt time is 60 seconds, then you make one unit / minute.
If the takt time is 15 seconds, then you make four units / minute.
60 seconds / 16.9 seconds = 3.55 ~ 3.6
Thank You Mark Great Information.
How do we Account for Downtime that is not in the equation for Takt Time?
Is there a way to improve our Efficiency with the help of Takt time if so, it probably does require to overproduce right?
Also If say you have a machine in which seems to be non operational or you are constantly fighting to keep it running and no means to justify the cost for a new one can we still then use Takt Time to acquire our Goals?
If not why then is Takt time being viewed as a great component of production?
It may be a very good theory but while using this I find it extremely difficult to motivate employees whom simply view this as a means to stop them from getting an early weekend without having to use vacation or personal, yes I believe personally takt time is great tool for helping eliminate injuries but at the same time it brings down employee morale Im not quite sure how my employees view this as bringing their morale down except they cant get done faster than they would like too…Could you please help me understand better why they think this???Confused!!!!
Jason –
If your equipment reliability is keeping you from producing to takt time, then it is telling you that you need to work on making the equipment more reliable (certainly not just buying new). There is an entire field of work called “TPM” that is about nothing but equipment reliability. It can be advanced stuff, though, and I don’t know your specific application.
On the other hand, if your team finishes early (I think you said you had three people) in spite of the unreliable equipment, then I have to ask “Do you have things you wish someone could help you with, but you can’t afford to hire any one else?” If the answer to that is “yes” then where your efficiency comes in is to work hard to get enough wasted motion out of the work that you only need two people to get a unit out every 3.6 minutes. (From your other notes, right now I assume you think you need three). Where takt time helps with efficiency is by letting you calculate how many people you SHOULD need if you had fewer problems, then you can work on some of those problems to get the actual work to match.
This is a topic that has books written about it, so I really can’t do justice to it in a short comment here. My first suggestion is to pick up a decent book about “lean production” and work to get the basics down. That should help you have better context for your questions as well as the answers. “Toyota Kata” by Mike Rother may be a little advanced for a beginner, but it does have good concepts that directly relate to the questions your are asking.
Your knowledge astounds me! Thnx again Mark
its very interesting, concepts.
many thanks,
What do you find interesting?
hi mark,
As a beginner want to understand how ppl come out with the no of pieces directly from cycle time.
I am into piston manufacturing industry is cycle time is machining time what comes on machine plus loading unloading time.pl .explain from scratch you can mail me.THANKS
if our requirement is to give 1320 units good at the end of shift what would be the C.T and Takt Time. pl. Explain with calculation for better understanding pl email if possible.’
Thanks again found page has good information!!
Thanks.
Rishi –
If you have to produce 1320 units by the end of the shift, you first determine your customer takt time – this is the “pure” calculation:
Net Working Time / 1320 units
So, for example, if you have an 8 hour shift (480 minutes), and subtract, for example, 40 minutes for breaks and meetings, you end up with net 440 minutes, or 28,800 seconds.
Your customer takt time would then be:
28,800 seconds / 1320 units = 21.8 seconds per unit. I round takt time DOWN so you aren’t building in overtime, so that gives you a takt time of 21 seconds.
If, though, you set up your production process to produce EXACTLY one unit every 21 seconds, you are assuming everything is going to work perfectly. It isn’t.
To compensate, you want to run processes a bit faster.
If you have good information regarding stoppages, quality fallout, etc, you can use that. Each would either subtract time or add necessary production volume to your calculation. The net effect is the same.
If you don’t have good information, a good place to start is taking 85% of the “pure” takt time and running with that. Then you apply PDCA to see what happens, and adjust.
This gives you what Mike Rother would call your “planned cycle time.”
Other people call it your “actual takt time” or your “operational takt time”
What it means is that, on a day to day basis, you use this faster time to drive your production pace.
In this case, it would be .85 * 21 seconds = 17.85 seconds. I’d round this to 18 seconds, close enough.
That means that each and every process is targeted at 18 seconds-per-unit for their standard.
The next step is to measure your actual output cycles, for the entire line, and for each major process step.
Thanks for clarification but how we got this 85% is their any basis.
If my machining time on screen of cnc machine is 27 Sec loading and unloading which is manual will take about 10 Sec as operator needs to orient the part also.So my net C.T will be 18.5 with two machine on this operation and this is more than what you have calculated as target what should i do then Whole machining has about 14 Process steps.
So,As a beginner want to understand how ppl come out with the no of pieces directly from cycle time.
I am into piston manufacturing industry is cycle time is machining time what comes on machine plus loading unloading time.pl .explain from scratch you can mail me.THANKS
Hey mark sorry to bother you again but i have lot of questions in my mind.
Besides from my earlier comment i am also interested in how i can reach to no.of operators required for a particular line this will help in budgeting the process.pl. help in clarifying with example.
Replied by email.
Key Points:
The first step is “grasp the current condition” Good tools are the VSM and the Toyota Kata Handbook downloadable from Mike Rother’s site.
I also advised that, based on the questions being asked, an experienced adviser / consultant, whatever would probably be a big help here, as there are crucial leadership systems that must also be put into place along with the “lean tools” if any of this is going to work.
nice article, easy to understand
can we use value stream for one part processing instead of for the whole factory where multiple products are produced?
Sivakumar –
The short answer to your question is “usually.”
It depends on the part you are selecting, and the scope of your mapping. If one part represents “the way your factory flows” then by all means, just map that at least to start. You will learn more than you know by just trying it.
Most VSM projects take on too much, as many plants have more than one value stream.
There may be a main-line value stream, with others flowing into it as well.
On the other hand, if all of your many products are made on a mixed line, then that part of the line is a single value stream.
Do the other answer is the classic consultant answer: “It depends.” 🙂
Hi!
I am really confused about takt time and cycle time. It would be really great if you could help me solve it. I am working with my Master thesis in a company. The company I am doing my thesis is a pharmaceutical company. I have identified all the processes and determined the cycle times. According to the takt time, it turned out that some processes has cycle times that are almost 3 times higher than the takt time. Therefore I say that they are bottlenecks, but according to the company, they are meeting the customer requirements/year. Hence, the processes should not be bottlenecks. How should I deal with this problem? Could you help me with this situation?
thanks!
Mike
Mikael –
Obviously if they are meeting customer demand, either the takt times or the cycle times they have determined are inaccurate.
It is kind of hard to coach you through the entire process in comments or by email, but rather than measuring the cycle times of those so-called bottleneck processes, try timing the output cycles – the intervals between units of output. Don’t worry about the cycle times right now.
My guess is that you will get better insight into what is happening.
Let me know how that goes.
Hi mark
we do carbide welding on our tools and send to our clients on rental basis.
We have to rent around 50 tools per month to our clients.
we have following 4 process to dress the tool.
1- Heating (cycle time 4 hours)
2-Welding (cycle time 7 hours)
3-cooling (cycle time 6 hours)
4- Grinding (cycle time 8 hours)
takt time is 11484 seconds that is 3.2 hours.
i have two operators one is looking after heating and welding another one is doing cooling and grinding.
How many more station of welding and heating would be required?
Do we need to purchase one more grinding machine for grinding operation?
could you please guide me.
Irfan khan
The cycle times you listed are likely process cycle times, not operator cycle times.
I doubt an individual operator is engaged for 6 hours for a tool to cool, for example.
I also imagine you are running things in batches, so it might even be too early to worry about this.
I’ll give you “minutes” for your takt time, so 3.2 hours = 192 minutes.
That means, in essence, you need one tool coming off the process every 192 minutes in order to make that takt time.
Please look at that as an intermediate- or long-term objective for right now.
What I’d like to know is: “What is the current condition?”
The takt time is part of that. It expresses what your process needs to do.
Now, what does your process ACTUALLY do.
First step here is to just get the output cycle for the entire flow.
That would be grinding.
What is the time interval between individual tools coming out of grind?
And by that I mean, collect the data series.
Tool 1: 0
Tool 2: 20 minutes (just making this up)
Tool 3: 21 minutes (that would be pretty typical)
Tool 4: 22 minutes
Tool 5: 180 minutes (that would also be pretty typical)
etc.
Construct a run chart graph of your data, with instances on the X axis, and time on the y axis. I am guessing you will learn a lot about the answer to your own question. But there will be more “homework” as well. 🙂
There will be more questions, but that is the first one.
Hi Mark,
I am in the process of creating a value stream map. I have a good understanding of what it is. I am a co op student, and i have been assigned to make a vsm for one specific product for our company.
we have several work stations for this product. We have about 5 assembly stations, in which different parts are assembled, and in the 6th one, all the different parts from the previous stations are put together. I was wondering, how i can create a linear VSM even with this sort of manufacturing process.
Also, usually in a VSm, i have seen just different steps, eg. 1. Cutting 2. Washing. 3. Coating 4. Drying
i would need to make one that says something like
1. Assembly 1
2. Assembly 2
3. Assembly 3
4. Programming
5. Testing
6. Verification
7. Packaging
\
I also needed to know how i can relate my VSM to finding TAKT times
Start out with a basic block diagram that shows how each process flows into its customers.
They may not be linear.
For example, from your comment, I get the impression that there is a final assembly step with several others feeding directly into it. If that is the case, then show that on your map – depict the feed relationships.
Hi Mark
I am doing value stream mapping (VSM) in my maste thesis. I have found that it is necessary to install a supermarket between two processes in order to reduce the overproduction. How do you decide how long time the goods should be in a supermarket?
I you assume that it takes one day to produce one unit in the process before the supermarket and that you decide that the market only should hold an amount of one unit at a time. Does that mean that one unit stays one day in the supermarket?
thanks!
Mike
Hello Mark,
I would like to implement single piece flow in my department. Could you let me know the general factors to be taken into account.
Also i wud like to know the importance of takt time for single piece flow.
Thanks
Regards
Sam
Sam –
Implementing single piece flow for your department depends a lot on what is stopping you from just doing it now.
Likely there are issues to overcome, or you would already be doing it.
So to answer your question, I would first need to know your current condition – a description of the process, the general sequence of steps, how product currently moves through it (batches, in waves, ??), etc.
One good measure is the output cycles – if you timed the interval between single units of production coming OUT of the process, what would that rhythm look like today?
While takt time is not strictly necessary for establishing single piece flow, you DO need to know the output rate required, and that is really the first grasp of takt time anyway.
Hi Mark
I am having an ongoing debate with my process Engineers regarding takt time and OEE. I have looked at the production process and feel that there is a good deal of scope for improvement with the possibility of creating spare capacity. This would them enable me to move staff over to other areas of the plant during the time created. My issue is that the engineers say the customer demand is 10 batches/week so they have worked out the takt time at approx. 0.5 days/batch ( working 5 day week ) and if we push to produce much faster we are not working to customer demand. My beleif is that we can produce the same amount over 4 days and therefore be far more cost effective
What are your thoughts on this and is it feasable to change the takt time
Thanks
Bob
My thoughts are “What obstacles are in the way of running to a level production schedule every day?”
Hi Mark and thanks for the reply.
There are no obstacles in the way as such I would just prefer to have the flexibility to move staff on to other processes and beleive the time gained would give me the capacity to do so. I would therefore like to reduce the time available to produce from 5 days to 4.5 days
Thanks again
Bob
Putting it another way, your capacity is not flexible enough to make one day’s worth of each product every day, so you want to make a week’s worth of one in 4.5 days, and a week’s worth of another once a week in 1/2 a day?
If so, the question is “What stops you from making a day’s worth of each every day?”
What problem (which I am sure is legitimate and real) would have to be cleared?
Great information!
We are a 500+ employee job shop struggling with implementing some of the lean concepts.
I am working on a project to free up capacity in our welding department (department is a scary term when talking lean). One of our “runners” is my main focus. Customer demand (at least for the next 6 months) is 5 weldments per week. Cycle time is 80 hours each. Takt time is 22.2 hours. We run 3 shifts, 39 hours/week on 1st and 2nd, and 33 hours/week on 3rd.
It is my understanding that takt time is what it is, and cannot be adjusted to free up capacity. How should i go about doing this?
The takt time is what it is (kind of), but keep in mind that takt time is an internal reflection of your external demand. Don’t lose sight of the purpose – it is a mechanism to “check” in PDCA, as well as a way to identify the minimum resources required to meet demand without overproducing.
You can’t “free up capacity” by adjusting takt time.
You CAN free up capacity by reducing CYCLE time. That is where your kaizen activities should focus.
Assuming the cycle time you gave is manual work, you need 80 hours / 22.2 hours = 3.6 people on the job all the time to complete this work, or you will fall behind. That is, of course, assuming that your cycle times are stable. If they aren’t then you will likely need more.
If you have MORE than that on the job, then the question is “What problems are forcing you to add labor?”
If your cycle times are accurate, the only way to “adjust the takt time” (meaning to run faster than 22.2 hours?) would be to add more labor, which takes away your capacity from somewhere else.
Obviously the 0.6 “person” is excess to your needs. The challenge, then, is to keep three people as busy as possible, and take up the slack on the fourth one. That person “catches” the issues and problems and works to enable the other three to have stable work cycles. With that, you have more visibility into those issues, and you can work to reduce their impact.
Yes, you are a job shop. But if you can apply these principles to learn how to quickly set up the most efficient job possible, break it down, and set up another efficient job, then you are establishing a core competency that will help you get more output at no additional cost, and gain capacity that way.
In addition to my last posting, we are currently meeting the customer demand for this product but falling behind on the various other jobs that come through. Usually, by the time we get a product running lean, it is out of our shop and we may never see it again.
Any help would be great!
Hello.
I am doing a training material for my company regarding how to calculate tact time.
In a book I am reading “Toyota production System” by Yasuhiro Monden he writes this regarding the time and quantity part of the calculation:
“Cycle time (Tact time) = Effectively Daily Operating Time / Required Daily Quantity of Ouptut.
The effective daily operating time should not be reduced for any allowance due to machine breakdowns, idle time awaiting materials, rework, or fatigue and rest time. Also, the necessary quantity of output should not be increased to allow for defective output.”
I get a bit confused when I now read your description.
Since I am not English natively speaking I might translate/interprate this wrong.
What do you think about his statement. Is it the same as you write or could it be that he has a different approach?
/Anders
No, he does not have a different approach.
However, there ARE breakdowns, there ARE breakdowns, there ARE problems of various times.
Those issues can, and do, cause line stops.
Toyota’s andon system makes sure of that, for example.
The question is “When are you going to make up the lost production?”
You have two choices.
1) Overtime.
2) During the regular shift.
If you choose (2) then you have to run some over speed so you have some time before the shift ends.
The ratio of the “pure” takt time vs. your effective takt gives you a metric of how effectively you have dealt with variation in work cycles.
Mark – I have a question. If my demand is 500 units per day, and I run two shifts, but the shifts are unbalanced – 7 on one shift and 3 on the other shift, how do I apply takt time? Net available time is 435 minutes per shift.
My goal is to have hour x hour charts for the area. It is my contention that I have different takt times per shift, with 350 units per 435 minutes on one shift and 150 units per 435 on the other.
Chris –
Let’s start with the theory, then apply it.
In the math, takt time has nothing at all to do with your capacity or capability.
The only inputs are (available time) and (required output).
Since you have 435 minutes available for both shifts, that is the same.
What is different is the required output.
Based on your statement of required outputs for each shift, you do, indeed, have two different takt times.
That is OK, the purpose of takt time is to give your team members a measure of success.
Where the real difference comes in here is that the required number of team members is an output, the result of a calculation, not an input.
In your case, you may (or may not) discover that that calculation gives you a different number than what you have currently populating each shift.
In practice, I realize you are adjusting the requirement based on the manning, but I encourage you to run through the analysis and determine the number of team members required and see what you learn from that.
I understand what takt time is but I am having a hard time applying it to my situation. I was recently hired by a small plastic thermoforming company (50+ direct employees) as the Process Improvement Manager. This company makes many different parts, both thin-film food packaging and paint sundry items like paint-tray liners. The machines are in-line thermoformers where plastic film goes in one end and plastic parts come out the other end where a person stacks and packages the parts while another person ‘operates’ two of these machines at a time. The changeovers are very time consuming, taking several hours each to complete. Obviously, reducing c/o is one of my goals. There are currently over 80 part numbers in the 6-7 week schedule, taking from 4-120 hours per production run. How do I calculate takt time in this situation, or do I even need to?
Don –
Takt time is simply a (very useful) tool that allows you to compare an actual cycle vs. an intended cycle for a machine, or a person. Though it has often been presented as dogma, it isn’t universal, though it CAN be used in more situations than most people think.
In your case, for example, you can set a “pitch” – a fixed block of time for a variable (but predicted!) amount of production. Let’s say you set the pitch at 15 minutes.
You would then verify, every 15 minutes, that you had done the work you expect to take 15 minutes.
You are looking to see causes of delay right away so you can respond, identify the cause, and then work to eliminate its cause.
Based on what you wrote, I’d focus first on a challenge of cutting your part number cycle (6-7 weeks) in half. (I said “challenge” because it won’t be quick or easy.) Stay focused on that.
If you want to talk talk through your situation in a bit more specific detail, hit the “Contact Mark” link on the right sidebar, drop me an email, and let’s set up a time to chat on the phone.
Great article
In Demand Flow Technology, they have a very specific vocabulary to prevent confusion about cycle times.
The lead-time / critical path through the value stream is called Total Product Cycle Time. (TPC/T)
The TAKT time is the rate of customer demand.
The cycle time at an operation is called an Operational Cycle Time (OpC/T)
Although some detailed concepts and calculations in DFT were questionable, I’ve always appreciated the clarity of the terminology.
DFT was a great example of what I call the noisy bazaar of improvement consulting and books. Whenever I encountered it, I found the separate terminology for the same stuff tended to put up a jargon barrier to learning the thinking behind the concepts.
The same effect can be seen in working to embrace the Japanese jargon.
Hi mark,
I am working on a thesis for my Masters degree. I am manufacturing a toilet which consist of 9 parts, the TAKT Time for the product is 50.6 sec.
The bottleneck parts I have are 5 out of the 9, in which all of the 5 parts have a higher cycle time than the TAKT Time
part 1 cycle time = 420 sec
part 2 cycle time = 198.47 sec
part 3 cycle time = 185.02 sec
part 4 cycle time = 104.49 sec
part 5 cycle time = 65.48 sec
part 6 cycle time = 39.9 sec
part 7 cycle time = 25.58 sec
part 8 cycle time = 16.68 sec
part 9 cycle time = 10 sec
I am wondering how can i meet the production plan, is it by using more than 1 machine for the part?
Cheers,
Ibrahim
Are these machine cycles, worker cycles?
What are you measuring?
Those are the total manufacturing time of each part.
The final product consist of those 9 parts which are at the end packed into one carton.
Questions:
1) I am trying to find how many machines for each part do I need in order to meet the demand of 144,000 product a year with a total available time of 2024 hours.
2) should I put each part of the product in one manufacturing cell?
3) should I put 2 parts or more to be manufactured in 1 Cell?
cheers,
Ibrahim
There is no single “right” answer to how you would arrange production.
A lot comes down to how you are measuring the cycle times, and exactly what you are measuring.
If these are automated processes, you want to know:
The running time for the machine.
The manual load/unload times for the machine.
and you want to know these for each operation for any one part.
For sure, if the RUNNING time for a machine operation is longer than the takt time, then you must have more than one machine, or you must break up the operation into stages. Which you do depends on the mature of the machines you are using. In any case, you must have a part coming to your packer every 50 seconds.
If there are entirely manual operations, then you are concerned mainly with the start-to-start work cycle of the each individual person.
The layout of the area should be driven to allow the manual work to flow, so that each operator has a work cycle that is balanced to the takt time as he tends to his unload/load operations and his manual operations.
Feel free to click on “Contact Mark” on the sidebar ——>
and I am happy to discuss details with you. I am going to need a more detailed understanding of the process before I can ask you more specific questions.
These are semi-automated processes,
So when calculating the number of servers needed on each part, Should I conceder the Cycle time of the machine only, without the loading and unloading time done by the labour?
I am working on a formula to find out the number of machines for each part:
* No. of machines = Production rate per min X Total manufacturing time of each part
Is this formula right or should I change the total manufacturing time to cycle time of the machibe without the loading and unloading time?
Thank you very much for your kindness and fast reply.
Best Regards,
Ibrahim
Ibrahim –
It would help a lot if I understood not only what you are trying to do in this production area, but what you are trying to learn for your master’s work — what is your working hypothesis?
If your thesis literature search has not included Steven Spear’s PhD (1999) dissertation from Harvard, then it needs to. I think that work would answer a lot of the questions you are asking.
There is no need to develop a new formula for determining what production resources are needed to meet the desired rate. The math is well known, including a Production Capacity by Process analysis (Shingijutsu / Toyota) or the simpler version of Cycle Time / Planned Cycle Time (which can also be expressed as Cycle Time / Operational Takt. Different words, same meaning.)
To answer your specific questions –
For a semi-automatic operation, you are chiefly concerned with two things:
– The full cycle of the process for one part. It looks like you have those.
– The actual automatic cycle component. This is important because if the automatic cycle is longer than your takt time, you clearly need more equipment capacity.
– The manual work component for each cycle.
That manual work, in turn, is:
1) Work while the machine is waiting, such as unloading a finish part and loading the next. This time adds to the automatic time, but can usually be reduced somewhat through improvements to the way the work is done.
2) Manual work that is in-cycle, such as tending to some aspect of the operation while the machine is running.
The manual work cycles, in turn, can give insights into how people work in combination with the equipment, and give you better manual work efficiency by improving the layout, etc, so operators can interact with more than one machine.
At the simplest level, though, you are correct. If you have a 50 second takt, and a 500 second cycle, you are going to need some 10+ positions to keep up.
If the overall cycle is longer than your takt time, you have two options:
1) Duplicate the production capacity.
2) If possible, break up the operation so it flows from one step to to the next like an assembly line, with each step paced to the takt time.
The second operation is preferable for a number of reasons that are outlined in [Spear, 1999], among others.
Another good resource for you would be Mike Rother’s “Toyota Kata” web site.
There is a link to it in the right sidebar under “Like Minds” ——>>>>
I am working on developing a new product, a revolutionary toilet with lifting mechanism for people with mobility problems.
The design was ready and I had to find the material to be used, estimate the production cost, find the best potential market and design a manufacturing facility that will be able to meet the demand of 144,000 toilet which was calculated after a wide market research.
All the calculations and manufacturing processes choices was generated by using a cost estimation software called aPriori, this software helped to calculate the production cost of every single part, and finally compare the production in more than 1 country (UK, Brazil and China) to see which country is best for the product. Also I am doing an extra work to find out the difference in production cost while having two different degree of automation (semi-auto which the software calculates it for you & full automatic which I am calculating it).
The main problem I had was calculating the number of machines needed for every part and the final design.
Thank you very much for your help and i really appreciate it.
Cheers,
Ibrahim
TAKT time is working very well in my production environment with processes that have a constant cycle time. However I have a tumbler machine that marinades meat, and I want to use TAKT time for this also, but each product I put through the machine requires a different tumble time (ranging from 5mins to 30mins). Approx 15 different tumbles each day.
I can control cleaning and loading times (for arguements sake, assume 5mins each cycle), but I can’t see how I can use a TAKT time concept when the tumble times are variable depending on which product is being produced. Is there some other iteration of TAKT time I should be looking into for this scenario?
Cheers / Matt.
Matt –
Sorry for the delay in replying to your comment. I’ve been very busy over the last couple of months.
The purpose of takt time is to establish a baseline for how long a process should take. In the case of your tumbler, you have variable “should” times. But each tumble is known.
Imagine a series of time slots, each 5 minutes long. You can load your tumble to take one slot (5 minutes), three slots (15 minutes), six slots (30 minutes) or anything in between. You know when it is supposed to begin; and you know when it is supposed to end.
Then as you actually run your operation, you compare the should starts vs. the actual starts and you will see very quickly when things start to get behind.
You can apply the principle of running a little faster by reserving a slot or two every hour (for example). That gives you the equivalent of the capacity headroom for problems that the “planned cycle time” provides. Or, you can schedule 5 minute slots, but only include 10 or 11 slots in an “hour” for the same effect.
The key is to understand the principles in the article, and figure out how to apply them to your specific case.
Matt,
you can use Takt time as an indicator as to the absolute limit you need to be able to hit customer demand.
You can then use planned cycle time for your machines, (which should always fall below the Takt time) as a target for each machine.
This effectively becomes your average target cycle time.
Planned cycle time can be measured as available demand (which you got from Takt calculation) minus changeover times between runs and also any allowances for stoppages (downtime).
You can then analyse this over the course of time to see the differences in time and the range between lowest and highest run rates. Are there any improvements you can make to bring the cycle times closer to he planned cycle time?
The important thing to think about is to monitor your actual performance against the limit that you must run at, which is takt. If you go over takt, then you will not hit customer demand for that period, so must get back on track quickly.
I can send you a bit more detail if you need it. Just ask.
I’ve just completed a time study and my longest operation is 70.3 seconds, 44 seconds of that is machine time, leaving 26.3 seconds of manual cycle time. The 26.3 seconds is slightly under the average of the rest of the cycle times in the cell. Do I stage more pieces in WIP here to releave this? If so, how do I figure out how many?
Tricia-
What is your takt time and planned cycle time? What level of output do you require?
WIP will not address a chronic imbalance, it only helps in absorbing variation, fluctuations.
Well, many people do not know many things. There is a need for articles like this. I hope you participate in IIE Linkedin community also.
Cost as a productivity measure was advocated in various papers by Baldeo Deo and Doug Strong. It is a logical thought and based on it, I advocate Total Cost Industrial Engineering. Visualize the total enterprise cost in terms of subsystems, processes and method that IEs study and improve productivity and reduce cost. Every time an IE study is there, its impact on total cost must be recorded on the TCIE map.
Well… I’d say instead that “many people are learning many things” and sometimes doing so by trying, and then having the intelligence to ask a question.
My company uses takt time (equal to cycle time of machine) to produce a quota per hour for each work center.
For instance the machine cycle time is 17 minutes so they set the takt time to 17 minutes and quota of 4 parts per hour.
The variables used are only setup time (300 min), machine cycle time per part (17 min), and total quantity to be made (268 pcs).
How can I explain to my Manager the proper use of Takt time when he uses only Setup, Takt time, and Quota on his 5S board?
Philip –
To answer your basic question “How do I explain to my manager…?” I first have to ask “Is your manager satisfied with the results he is getting today, or does he want a different outcome than he is getting?”
If he is happy with the current results, then there won’t be a lot of reason for him to think his use of takt time is improper, and all you will be doing is trying to tell him that something which is working is wrong somehow.
But going back to the top of your comment, it likely isn’t working if only because it is going to take 68 minutes to make four parts, so there is no way to succeed if the quota is 4 parts per hour.
What you can do depends on what your manager expects you to do.
If you can find the time, some of the things you can do are to understand more about how the process actually performs – why it takes six hours to do a setup for example – and whether or not it actually takes 17 minutes to make a part.
You can look for sources of variation and delay in getting the work done.
Is the equipment operating as fast as it should or as fast as its capability?
You can set up some visual controls to check production against the expected performance, and seek to understand causes of delays and work on those.
Anything you can do to gain real observations, actual facts, actual information about how the process actually performs will then give you insight into what can be done to improve it.
Once you are trying to improve a process, rather than just define the required output, the principles you are reading here make a difference.
Hello Mark,
I am working on implementing OEE in one of our machines that makes centertubes for automotive oil filters. The steel is rolled and each part number has specific diameter and length. However, the run-rates vary for each part numbers. I am somewhat able to calculate Takt time for each part number based on the standard run-rate. However, the problem for me is to determine Ideal Cycle Time. The machine can run as fast as 65 PPM for one part number while it runs as slow as 13 PPM for some other part number. In this case, what would be the optimal way to calculate Ideal Cycle Time for each part numbers? As you know, Ideal Cycle time is required to calculate Performance Metric of OEE.
I look forward to your feedback. Thanks!
Shirish
The “Ideal Cycle Time” in regards to OEE is yet another use of the term “cycle time” that I didn’t even mention in the post!
Since the OEE calculation is used to determine a ratio of “actually running” vs “could be running” (in the most over-simplistic sense), my approach would be to either pro-rate or determine the OEE separately for the two items. The second approach would probably give you better information, as you very well might have issues with one part that you don’t with the other. Yields, for example, could be different.
OEE, in general, is a decent overall PERFORMANCE metric, but not a very good PROCESS metric as it is an aggregation of many factors that need to be addressed separately if you want to improve anything. So be certain WHY you are calculating it – and what problem is solved by doing so.
I have one process containing 114 different machine cycle times resulting from 91 potential products. To these times I will be adding delays from frequency items, planned stops, and attempt to account for unplanned delays (historical?). Up to 4 machines can be staffed in this area – all producing the same product together due to a single piece of equipment feeding this process. Product mix changes weekly based on customer demand. Machine reliability is not an issue.
Any suggestions on how to establish a takt time for this area in such a way the operators can determine hourly schedule based on mix and # machines staffed?
You likely want to establish fixed blocks of time containing adjusted levels of production based on the product running at the time.
For example – you are going to establish a “check” every 15 minutes.
If you are running product that takes 2 minutes to run, then you would expect 7 or 8 to be completed.
But if you are running a product that takes 3 minutes to run, then you would expect 5 to be completed.
The details of managing this would be really dependent on the actual flows and staffing in the area. I have some thoughts, but would really just be speculating unless I could see the area of a fairly detailed flow map.
The key point is you want to establish a “normal pattern of timing” so you can verify progress against it, but do so without injecting complexity into your process or your management. That normal pattern may adjust based on the product, but no matter what, you want to establish robust visual controls so you can compare the actual rates against the target rates and quickly see any difference between the two.
Hello Mark,
Very good article and insightful. I am working in logistics, but I see my work really as supply chain management. I try to see every part of the process of delivering products (internal and customer products) as working under a specific rythm(takt time). BUT you have division of work and I know there are problems between what the people in production and logistics.
Problem- I asked ONE simple question to the production people:
What is the problem with the products coming out late at assembly?, Do you have a bottleneck somewhere?
I could tell by the look in their eyes, they were telling me, ¨mind your own business logistics guy¨
Turns out: do you know how they calculated the cycle time for a process involving 3 machines that do exactly the same job and 1 guy tending the 3 of them?
load time: 45 secs
machine time: 4 minutes
Unload time: 45 secs
the operator switches on the machine at the end of the load time at machine 1 and goes to the other 2, loading and switching on…
They say, total cycle time: 7 minutes, in which time, 3 products were processed. (agreed)
They say: ¨a product comes out every 2.33 (7/3) minutes, so the capacity is 1/2.33 = 0.428 times 60 minutes = 25 products per hour¨
BUT, processing time is 5.5 minutes per product, NOT 2.33. shouldn´t you calculate as follows?
3 machines/ 5.5 minuntes (p time) = 0.54 * 60= 32 products?
Is that correct?
Thank you Mark
Adrian –
Regardless of the calculation, the answer is “Get a stopwatch and time the interval between outputs.”
THAT is the cycle time.
The math can give insight for understanding why, but start with reality.
Hi Mark,
I am a college sophomore going for Industrial Engineering, and I came across your article. It’s very clear and helpful for a beginner like me. I was wondering if you could recommend some books or other more in-depth readings that might help me as someone brand new to lean and six sigma ideas.
John –
I’m not sure what a current industrial engineering curriculum includes these days, but I would hope it is heavily steeped in these principles. I imagine, though, that it covers the technical aspects but likely leaves out or glosses over some of the cultural / leadership pieces that are crucial for complete success.
To expand on the technical education you are likely to get, take a look at:
Steve Spear’s PhD Dissertation. This was breakthrough research that linked the technical aspects to how a continuous improvement culture works. It is a precursor to Mike Rother’s work on “Toyota Kata.”
Jeff Liker’s book series on “the Toyota Way” is another good source.
The most important thing you can gain, though, is a focus on what people are doing rather than exclusive focus on the product and process.
A factory is “people using tools to make a product.”
It is all to easy to lose sight of that and think of the people as operators of machines that make products.
The mindset between those two statements is completely different, and gives you different results.
Get article and very easy to understand. I like to teach cycle time as “the agreed upon average amount of time it takes a worker to complete an entire sequence of work”. So to you earlier comment that ” the cycle time of a process may exceed the takt time” is true. It may alao be well under the take time which most people would say that is good but when this happens you incur the waste of waiting and may likely have excess capacity if it occurs at multiple processes. A simple way to explain takt time is “the rate of customer demand”. You can’t get much simpler than that. Your harasey statements are classic and those who think you don’t need cycle time and takt time will continue to work in the dark until they ” learn to see”. No pun intended! I have a question for you, since we r talking about this topic lets throw “pace” into the pot and see if we can cause more confusion. Would like to hear people’s thoughts on “what is pace” whether its in manufacturing, distribution or crossdock operations
In the above formual: Available Minutes for Production / Required Units of Production = Takt Time should we not be considering the no of employees performing the task? I am in service industry and unlike manufacturing the no of employees (hrs available) impact the speed of the execution. Typically on any Takt calculator you would observe the following fields:
Working shifts / day
Hours / shift
Available time / shift
Break time / shift
Lunch time / shift
Planned downtime / shift
Net working time / shift
Net working time / shift
Net available time / day
Customer demand / day
Net available time / day
Customer demand / day
The above factors doesnt accomodate the no of employees it only takes care of the shifts involved in my project i only have one shift but not sure how to accomodate the impact of no of employees (no of hours available)
The number of people is calculated with the takt time as an input.
Takt time is simply the normalized rate of demand.
To figure out how many people are required, you also need to know how much time is consumed to perform one unit of work.
Dividing the cycle time (measured) by the takt time (calculated) gives you the absolute minimum number of.people required to meet that level of demand.
Note that variation in cycle times, factors in how the work CAN be broken down, etc typically make that number somewhat higher.
This is one reason for setting a (faster) planned cycle time for that calculation. This tells you how much extra capacity you need to meet the customer’s requirements in the face of these problems you have yet to resolve.
Hi Mark,
I work in an aerospace company and want to introduce my people to Takt time. we are in the process of identifying the part/process families to be able to have cells or dedicated lines/ machines.
my question is when you calculate the Takt time, how do you consider you setup and cycle time. lets say your takt time is 5 min , your set up time (for the batch of 15 parts) is 3 days and your C/T is 4 hours. how do we possibly produce every part is 5 min?
Somayeh –
Your question has two parts.
The first one is how to accommodate changeovers. The second is asking how takt time relates to the lead time of production. I am going to address the second question first:
Takt time expresses the rate of output your process must maintain to satisfy the customer.
Think of this example, which is actually pretty similar to yours.
An automobile assembly line typically has a takt time on the order of a minute. Let’s say 60 seconds just to make the discussion easy.
But it takes close to six hours to actually assemble the car.
That line, therefore, has ~400 positions in a row, each operating to the 60 second takt. Of course it is easy to see in this case because it is a moving assembly line.
But the principle is the same.
If the takt time is 5 minutes, and it takes 4 hours (240 minutes) to make the part, then you need to have more than one in work at the same time.
420 minutes / 5 minutes = 84.
This means that you need 84 units to be in work at any given time if you need to finish one every 5 minutes.
It doesn’t matter whether or not they are being made individually or all in a row (like an auto line), you need 84 in work.
If you are succeeding, likely you are running batches around this size, and finishing them all more or less at the same time; one batch every 4 hours or so. (This does NOT take into account your 3 day(!!) changeovers yet)
Depending on the technical limitations of your process, this may well be necessary. But if your customer requires a part every 5 minutes, and you are making 100 of them every 4 hours, it means that 99 of those parts are done early – overproduction. When you really look at the size and scope of the capital equipment required, this can radically change your mindset, though most companies who are just beginning aren’t ready to have their brains bent that much.
This then brings us to your first question – changeovers.
In your case you are saying changeovers take 3 days. My first question is Why?
I’d be working really hard to half that time, then half it again (as a starter). But right now, it is what it is.
I don’t know how many different items you have in your product family, so can’t calculate the logical batch size with the information you have given, but I imagine it is huge (though your actual batches are probably bigger than necessary – that is pretty common).
Your PLANNED CYCLE TIME is going to be quite a bit faster than your takt time to “make up” for the changeover losses. As I said, we would need more information to calculate what this would need to be, and to put it into terms that are meaningful for the people doing the work.
But the takt time remains at 5 minutes because that is what your CUSTOMER demands. Your customer doesn’t care about your changeover times, they just want a part every 5 minutes.
pls give more examples for takt time
My cycle time is 155 sec…and my part transfer time is 32 sec. I need to calculate the production rate…
Let me give available info’s
Units produced per shift=160 per shift
No of shifts per day=2
Shift working hours=8 hrs(excluding break time)
Vinay –
Takt time only has two inputs:
– The time available.
– The production required.
In your case, you have 8 hours per shift, which you say does not include break time.
You have two shifts.
That gives you 8x2x60 = 960 minutes of available time.
During that 960 minutes, you must produce 160 units of output.
Thus:
960 available minutes / 160 units of output = 6 minutes / unit of output.
Your takt time is 6 minutes, or 360 seconds.
Your cycle time does not change this – to satisfy your customer, your PROCESS must DELIVER a unit every 6 minutes, no matter how long it takes to make one.
To use a common industrial analogy, it takes about +/- 6 hours to assemble an automobile, but the takt time is ~60 seconds. The assembly line is about 400 units long, however. Thus, each car spends 60 seconds in each position, and each minute one car is started, and one car is finished.
In your case, you say your cycle time is 155 seconds.
Since you need a unit every 360 seconds, you actually have quite a bit of excess capacity.
You can SLOW DOWN to 360 seconds.
The challenge / target for you would be how you make productive use of that extra time.
Hello Mark, first of all, great insights about the nuts and bolst of Lean.
I dont know if you have covered this question in the past, but Im wondering the following.
Current Situations is that a Manufacturing Cell can run different part numbers, (A, B, C, D,..W)
Part number A is the high runner with approx 60-65% of allocated time devoted to run just this part number.
The rest part numbers are run throuought the week.
Would in be fair to calculate Takt Time of the cell with just Part A demand?, assuming that the demand of the rest of the products is not relevant (too much granulated) or Do I have to take into consideration ALL Demand for that specific cell.
Topic number #2 is in regards that these part numbers have differente cycle time, hence, when we calculate Required Crew (Sum CT/TT) in some cases the requierement is bigger than the current manning, (the cell is set to have 5 people) so, would it be fair to determine individual Takt Times for each part number?
Fernando –
>Would it be fair to calculate takt time of the cell with just the Part A demand?
Doing so would not be meaningful since you actually have to run about 35-40% faster to make time for the other parts.
Think, not in terms of individual parts, but “Units of Work” or “Units of Production.”
In most cases, the “Unit of Work” is one part, and I think that is the case here.
How many “Units of Work” do you have to complete in the time you have to get it all done?
As for differing cycle times, you are now entering into the possibly complex topic of mixed-model production.
The answer really depends on how different the cycle times really are, and why they are different. The best way to manage and pace a mixed model line is dependent on the specifics.
In general, though, you want to strive for a steady pace of work, and NOT shuffling the crew around. There are a lot of ways to get to that, including defining the “Unit of Work” as a time-balanced quantity of the given part. For example, if Part A takes 90 seconds, and Part B takes 60 seconds, your “Pitch” could be 180 seconds. No matter what you are running, you are pacing the work in 180 second intervals. If you are running Part A, you need to have two of them done; part B- 3 of them.
Changeovers are another factor you have to take into consideration.
The longer they take, the more capacity you need (the faster you must produce).
For me to get into more detail, I’d need some of the specifics, and a better grasp of your current condition and where you are trying to go for your next level of performance. All of these things are really just problems and obstacles, and we are discussing possible countermeasures.
As for as my understanding;
Takt Time means the standard time set for any given product to manufacture by the top management.
Cycle time:It is the actual time taken to produce the product which can be found by doing a motion study.
Vinay –
Takt time has nothing at all to do with time standards.
I have a question if you don’t mind sharing your opinion with me regarding “Takt Time”. I’ve been asking around but no one really has a firm answer.
We all know that, Takt time is total available hours (minus breaks, lunches, etc) / demand.
Here’s some of the information / case study:
– Product A and product B are going to be married together at the customer’s location
– Customer demand for product A is 2033 parts/day
– Customer demand for product B is 2033 parts/day
– Total available hours is 22.5 hours/day (81,000 seconds/day)
– The Takt time for product A is 40 seconds/part (81,000 seconds/day divided by 2033 parts/day)
o Therefore, Takt time for final assembly is 40 seconds/part
o However, prior to reaching to final assembly, the product A needs to go to CNC process
o There are 7 CNC machines to supply the demand for product A
o My questions
? What would be the takt time for product A at CNC process with 7 CNC machines used?
• Is it correct if the takt time for product A at CNC process with 7 CNC machines used = 81,000 seconds/day divided by (2033 parts/day divided by 7 machines) = 279 seconds/part ?
– And, in the meantime for product B:
o The Takt time for final assembly is still 40 seconds/part
o However, prior to reaching to final assembly, the product B needs to go to CNC process
o There are only 4 CNC machines to supply the demand for product B since the cycle time of the machine is faster than the CNC machines for product A
o My question,
? What would be the takt time for product B at CNC process with 4 CNC machines used?
• Is it correct if the takt time for product A at CNC process with 7 CNC machines used = 81,000 seconds/day divided by (2033 parts/day divided by 4 machines) = 159 seconds/part ?
If I can hear your inputs, it would be appreciated.
Thx.
Adrian
Adrian –
The takt time for all of the parts is 40 seconds.
By taking the cycle time of 1 CNC machine to produce 1 part, you can divide by the takt time (actually the planned cycle time, which is somewhat faster) and calculate how many CNC machines you need to meet the production requirement.
At the CNC machine, however, there is a planned cycle time for operation, and you should be measuring your actual run against that planned cycle time to ensure each machine is producing as fast as necessary / planned.
Then again, I’ve seen a couple of teams think beyond the “fixed” cycle time, and shift toward in-line stages with simpler, cheaper machines, saving the expensive high-precision equipment for the final machining, and thus using fewer of them.
Backing up a bit –
Takt time is an expression of customer demand, and only has two variables:
– How many must be delivered to the customer.
– How much time is available to deliver them.
Cycle time, on the other hand, reflects the realities of production.
In reality, though, the difference can be semantic. In everyday conversation on the shop floor, even though they are running to a planned cycle time, they are likely to use the term “takt time” since that is what they experience. Just to muddy things up a bit, “planned cycle time” can also be expressed as “operational takt time” or “actual takt time” as distinguished from “customer takt time.”
So you see, the words matter a lot less than the principle:
– Know how long you have.
– Verify the actual time against the prediction.
– Respond quickly to anything that is abnormal.
Hi
We have 2 machine produce 3 types of products with different cycle time, such as A product cycle time is 15 sec, B is 20 sec, C is 100 sec. The weekly demand for A is 2000, B is 1000, C is 50. 2 shift and 5 working days. Then the takt time is 82 sec. then C product can’t be meet, it seems. what’s wrong am I? Because in fact, we can meet the demand. Thanks!
Joe –
The short answer is you are making up time when running the faster A and B product, then using that time for running the slower (and lower volume) C product.
Keep in mind that for product takt time, the number of machines you are running is irrelevant.
The only factors are:
– How much work (how many items) must be done?
– How much time is available to do the work?
But there is more to the story –
My real question is what are you striving for?
What are you trying to achieve?
Based on your weekly demand:
A: 2000 units/week x 15 seconds = 30,000 seconds per week.
B: 1000 units/week x 20 seconds = 20,000 seconds per week.
C: 50 units/week x 100 seconds = 5,000 seconds per week.
Giving a total cycle time of 55,000 seconds per week,
which works out a little over 915 minutes per week,
or about 92 minutes per shift of actual capacity used.
That leaves you about ~ 6 hours per shift for changeovers.
If you are actually working 2 shifts x 5 days to get this product out, and aren’t producing other products on this equipment as well, there is a lot of upside for productivity if you need it.
does adding a operation decrease cycle time.
in my company there is a turning process which they are doing in 3 setups that is turning1,turning2,turning3.
each takes 30 seconds so the total time comes to be 90 seconds,
that process could have been done in 2 setups also but they say to decrease cycle time they are doing it and they say that we will get a part in every 30 seconds
i somehow am not getting it because it is moving in sequence. T1 then T2 and T3.
could you resolve my dilemma
[Edited by Mark to add paragraph breaks for legibility. ]
prjc –
Your question reflects what I am trying to address in the original post.
I THINK you are saying that your total operation requires 90 seconds of turning time.
This is the TOTAL cycle time required to complete a part.
But you have to COMPLETE one part every 30 seconds.
This is commonly called takt time, but can also be called planned cycle time, or even “cycle time” by itself. Many books from the mid-1980’s use the term “cycle time” to refer to what we, today, call “takt time.”
It might be technically possible to complete a part with two turning operations.
But if you did it with only two, one of them (or both of them) is going to take longer than 30 seconds, so the system cannot complete a part every 30 seconds as required.
The engineers in your company recognize that, in order to complete a part every 30 seconds, no single operation can be allowed to take longer than that, so they broke the operation up into 3 parts rather than just 2.
Hi Mark,
I am currently trying to determine the cycle time of a station, and my plant currently sets up the operators to work between stations.
For an example, after station #2 operator is done with his process, he would walk over to station #1 and continue on where operator in station #1 left off; then bring those parts onto station #2 and go on.
But my question is how to determine the cycle time for station #1? Because most of the time the parts are sitting there at station #1 waiting for station #2 operator to pick it up.
Do I incorporate the waiting time of the WIP in station 1 into the cycle time? (Notes) the time it takes for the operator from station #2 to continue on the process at station #1 varies greatly (The waiting time of the sitting parts in station #1).
Hi Derek –
You’ve got a couple of things in play here.
The OPERATOR cycle time for station #1 is measured from the time the operator BEGINS one cycle until he BEGINS the next one. (or end to end – key is pick one point in his work cycle, like the finish line on a race track, and measure from there).
This does not include the WIP waiting time, unless the operator is also waiting.
Likewise the operator cycle time for station #2 is from touching the part until touching the next part, for example.
For this small part of the operation, the EXIT cycles are likely being paced by operator #2.
If you operator has a consistent component of waiting in his cycle, make a note of it and subtract that from the operator cycle for the purpose of target labor calculations.
If WIP accumulates between #1 and #2, then you have a work balance issue of some kind being hidden by the overproduction of #1. Without knowing the takt time, I can’t go any further with that.
At the end, though, whether or not your downstream customer’s needs are being met depends on the cycle of #2.
If this thoroughly confused you, click on the “Contact Mark” link on the right sidebar, drop me an email, and we can chat on the phone.
Also – look at Mike Rother’s “Improvement Kata Handbook” – especially the section on “Grasp the Current Condition” for a good primer on this.
Hi Mark,
Thank you very much for answering my question.
Hi Mark,
I am an internship student from Singapore. In my company my supervisor asked me to evaluate cycle time for processes individually of an assembly component. The assembly component enveloped 6 processes, and I do have the cycle time for per piece each of it. 8 hours total working hours (not including break and lunch time) for the labors who doing this assembly. And he asked me to reduced the cycle time by doing calculations to get the exact time, so that can increase the productivity.
Standard Cycle time:
1. 11.06
2. 6.43
3. 10.85
4. 8.81
5. 12.48
6. 8.68
They asked me to evaluate the cycle by using some industrial engineering methods, and I am lost in my tasks since I have no any basics in this case study, even I have searched in internet but I couldn’t understand the theories of cycle time calculation. Please do help me in this task, will be appreciated.
Thanks,
Vinod
Vinod –
There are a lot of structures you can use to carry out this assignment. One of the more robust ones is outlined in Mike Rother’s “Improvement Kata Handbook” available for free download from his web site.
You really should go through all of it, but the for our purposes here, I suggest you go to the section on “Grasp the Current Condition” It contains a solid baseline for understanding, not only the cycle times you are trying to measure, but the context for them.
BUT, as I said, to carry out the entire assignment, you should start from the beginning, and understand the goal or challenge you are trying to achieve, calculate the takt time and planned cycle time, then seek to understand why the process currently performs as it does.
From the numbers you gave, I can already see there are likely some work balance issues, but without knowing the takt or planned cycle time, it is hard to say what the opportunities are.
If you go through the exercise in the Improvement Kata Handbook, and are still not sure, drop me an email via the “Contact Mark” link in the right sidebar. —->
– Is cycle time a critical variable influencing the division’s productivity?
– May more labour hours on off-line processing reduce cycle time significantly?
Celia –
Since cycle time is simply a measurement of how much time it takes to do the job, I’d say it is the numerator in any calculation of productivity.
Moving labor hours from one task to another doesn’t change the cycle time.
How to calculate cycle time during manual operation ? Especially grinding during batch production? What will be the fatigue allowance to be considered?
Harer –
Based on your question, it sounds like you have a “grind department” where there are simply many people grinding as fast as they can, and you are trying to determine how fast you can ask them to go.
In traditional industrial engineering (which goes back to the year 1910 or so), there are many factors to consider, and first and foremost is to optimize the motions to eliminate elements of fatigue.
You would do this through careful observation and measurement.
The result of this would be enough knowledge to know how fast you can ask a worker to perform the task.
However I believe your factory would be much better served if you attempted to get flow production into place. Looking at your company’s web site, I see your product is very straight forward, and that would likely not be difficult to do.
That would completely change the nature of the problems you are trying to solve, in addition to likely cutting your product flow time to a fraction of what it is today.
Dear Mark,
Thank you for providing informative info.
In a transformer manufacturing unit,if there are 22 semi automated processes and most of the process cycle times are either above or below the takt time, where is the scope for improvement when the processes can neither be combined nor be broken down?
Please find below the available information
Customer Demand/Month 24360
Total Available Time 720000
Takt Time 29.55665025 secs
Cycle Time 468.6 secs
No Of Operators Reqd 15.8543
Awaiting for your response.
Supritha –
My first question is “What do you need to be able to do that, today, you cannot?”
That direction / challenge question tells you where you need to start looking.
I see your demand level – are you performing at that level today, or falling short?
What do your exit cycles (time between units coming off the end of the line) look like?
Is there a ton of variation, or are they steady and consistent?
Are they above or below the takt time?
We would need to know the specific cycle times for each and every operation, both the automatic and the manual.
If the operations are “semi automated” – does that mean the operators unload / load machines that then run on automatic cycles?
If so, what are the automatic cycles, and what are the unload / load times?
How is the labor broken down?
Are operators waiting for equipment to cycle?
Is the equipment reliable?
What changeovers are involved?
My first suggestion would be to download the “Improvement Kata Handbook” here:
http://www-personal.umich.edu/~mrother/Materials_to_Download.html
then specifically do through these sections:
Direction and Challenge: http://www-personal.umich.edu/~mrother/Handbook/Direction.pdf
then Grasp the Current Condition: http://www-personal.umich.edu/~mrother/Handbook/Analysis.pdf
Once you have done those things, then you have enough information to answer your question “What is the scope for improvement?” meaning “Set your next target condition.”
Dear Mark,
Thank you very much for your quick response. Much appreciated.
I have joined a transformer[small ones mainly used in energy meters] manufacturing company and am given the responsibility to analyse and come up with a lean journey plan. It is a well established company which is in business since 26 years with 150 + employees in India delivering around 3 million transformers of various kinds per annum.
I thought starting with calculation of Takt and Cycle Times and analysing if each of the processes are working within the Takt would be the first step. Am I on the right track?Please suggest.
Awaiting for your guidance and response.
Calculation of the takt time is a good first step.
Measuring cycle times is part of understanding how the processes currently flow.
The links I suggested provide a very good step-by-step guide that should keep you on the right track.
Dear Mark,
Thank you very much for the guidance and links. The links are very informative.
I have started with noting of 25 exit cycle times for each of the 22 processes involved in manufacturing of one of the products.
Looking forward for your support and guidance.
Supritha –
I will be interested to see what you have learned.
Hi Mark,
Awesome article. I need bit more help and clarification. We have consultants trying to teach us lean.
Today they gave example of toyota. Told us that every 44 sec one engiene was getting shipped to a truck and 44 sec was takt time. Asked us to note that 44 sec is not cycle time to build engiene as it could take several min to build engiene.
Then they taught us standard work combination sheet and percent load chart. Now the confusion begins…
We r told that standard work combination sheet is to see which process needs fixing. If it takes more time on chart compare to takt time then we have problem on hand. Similarly for percent load chart if we have operators cycle time going above takt time we have problem.
So now if we go back to engiene example if operator is taking 10 min to build engiene but takt is 44 sec do we have a problem?
Especially when we have several operators working on the process pumping an engiene out collectively at every 40 sec. So why does standard work comb sheet and percent load chart for this would reflect that process is not meeting takt?
What is that consultants are confused about and can’t explain?
Jig –
If the takt time is 44 seconds, and one operator would need 10 minutes to build an engine, you would need:
600 seconds total cycle time / 44 second takt time = 13.6 rounded to 14 people to build engines.
If ANY ONE of those people had a work cycle that exceeds 44 seconds, then you have a problem.
The percent load chart should show one bar for the cycle time of each individual operator.
The standard work combination sheet should reflect the details of the work cycle for ONE operator. So in this case, you would have 14 standard work combination sheets.
By looking at your current work balance, and the details of the work flow, you might see opportunities to reduce the total cycle time required.
So.. the first question is “What is your target condition?” What are you trying to achieve?
I am assuming that your target condition here would be to make the 44 second takt time with 14 people.
What is your current condition now?
Perhaps you cannot make the 44 seconds takt time, or cannot meet it consistently. I don’t know, you didn’t mention what the problem was. I am assuming from your question that this is the issue.
OK – so what obstacles are now in the way of meeting your target condition?
The standard work combination sheet is a good tool for analyzing the work cycles to answer this question.
Perhaps the work combinations on paper are all good, but you have observed one operator that sometimes goes over the takt time.
Why? What does he have to do that is outside the planned work?
Now you are getting down to the real issue.
Thanks Mark,
your reply is helpful. The problem I described is the example our consultant gave us. The confusion I still have is in understanding why our consultant is asking us to do SWCS for a cycle of work and then asking us to draw takt time on it. What objective it is going to accomplish?
Also we are asked to do % load chart for the operator and again have a line drawn for the takt time. If we do what is being asked it is giving an impression that the operator in the example is way above takt time and never meet the takt time.
I hope I am able to explain my question properly. Plz feel free to let me know if I can add anything further.
The situation I am sharing is not real it is a teaching example our consultant gave us yesterday.
You draw the takt time lines on those charts so you can compare your actual cycle (what you observed and measured) with the target cycle (in this case, the takt time).
The takt time is a “have to” number.
If the cycle time is longer than the takt time, then there is no way, ever, that you can meet the required rate of production to satisfy the customer.
If you have 10 people working, and even one of them is consistently above takt time, the entire line will be paced by the slowest person.
Therefore, you must either improve the work cycle(s) so that they are all less than the takt time; or rebalance the work cycles so that no work cycles exceed takt.
If you don’t draw the takt time on the chart, it is difficult to see that this is a the objective.
Hello,
We are preparing to build a biofuel production plant.
I am looking at shift hours and production targets.
Our production target for the year is 2MGY, over 24 hr days/ 5 days a week (this is a target production time and is flexible).
We are discussing the number of shifts in per 24 hours. I want to move to a 35 hour work week. I have a theory that if I take a No. that divides into 24 hours plus one hour, that I would have the employee times necessary to compensate for meetings/shift changes/etc. For instance, If I use a 6hr shift (employee is on the plant floor) plus one paid hour where the employee has 30 mins. before and then again after their shift for meetings/email/etc. that I would eliminate the times the production line is down (or half capacity) except for equipment repairs…the weekend is when we do maintenance.
What I am wondering is, how do I calculate the takt time for a comparison between a 6+1 hour shift vs a traditional 8 hours shift where the shift change/meetings etc happen within the shift. Not sure if this makes sense I am not an engineer. I want to see which work week hours are more productive. I had read that from the 1980’s to 1990’s the metal industry in Germany, moved from 40 hour weeks to 35 hours and “run times” increase by 11 hours. I want to tests what is the best employee shift hours for continuous run production times.
T. Mancini –
The “available time” is time available for production.
The reason we subtract breaks and such is that in manual operations, such as assembly, no production is happening during these times.
If you are producing 24hours x 5 days, and manning production during all of that time, then your available time is 1440 minutes per day, regardless of when individual people come to and from work.
Hi Mark,
I have an issue with calculating my TAKT.
Do I use forward customer demand (Which is consistently changing one day to the next) and plan production based on this TAKT or do I use historical data over say 1 year and calculate TAKT based on this.
If I use forward demand how often should I look at amending the TAKT times (Every day every week every month) and does this mean that my operator balance charts should be adjusted in line with demand changes every day week or month etc. that the TAKT target is calculated for?
Thank you
Hi Sam –
You are entering into the art of production leveling (sometimes called “heijunka” in Japanese).
The specific answers to your questions are “you get to decide.” 🙂
The target condition is to hold production as level as possible.
Setting the takt time essentially sets the target capacity for the system. The whole point of the “just” in “just in time” is you don’t want to expend resources to produce more than you need.
That being said, there is nearly always some inherent flexibility in the process, due to rounding up for example.
In practice, though, what you want to do is set up a buffer to protect production from the day-to-day fluctuations in demand that you cannot control. (You also set up a buffer to protect your customer from production fluctuations you should control, but that is a different story.)
Typically the buffer is either backlog, finished goods, inventory at your pacemaker, or some mix of the above.
The “keep it simple” rule applies here however.
Then I usually start looking into the system to find self-inflicted sources of variation. Reorder points, for example, tend to accumulate demand and then trigger a big surge. It is pretty common to see this if you are selling through distributors.
So… what all of this means is that operating smoothly at takt is a target.
What are the obstacles?
Start tackling them one by one to either eliminate them or mitigate them.
Thanks Mark,
Okay, unfortunately that’s what I thought you were going to say… I was hoping for a definitive ‘this is best option’ but I guess there isn’t one 🙂
So I have another problem in building safety stock because what we produce is always bespoke for each customer. The basics are the same for manufacturing but they are always slightly different in size and shape colour etc. Would the best option in this case? Buffers to ensure enough product to hit completion date?
Thank you
Hi Sam –
Fundamentally, you have the most efficient production if you can level the consumption of production capacity.
The capability for handling fluctuations comes at a price – you must have excess capacity when you don’t need it.
Takt time is simply a tool, it is not dogma.
You haven’t mentioned what your production throughput times, value stream, etc. A lot of this discussion would hinge on the specifics of your situation, what value you provide your customers, etc.
Unless you are operating strictly hand-to-mouth every day, you likely have some kind of order backlog (since you can’t ship from finished goods). That backlog can be managed to buffer production from day to day fluctuations. You would, though, need to put clear indicators on it so you knew if, over time, you had a mismatch in production rate vs. order rate.
If you ARE completing orders on the same day (or day after) you receive them, then I’d ask the question “What are you trying to accomplish that, today, you cannot?”
Hi Mark,
I really need your help, I am trying to apply TPS concept in our laboratory, and I’ve already gathered the time and motion data per analysis of our microbiological unit. I have a total of 7 different analysis with different no. of samples per day and different cycle time and i want to know how to come-up with the overall taktime which I can use in yamazumi chart.
See the data below;
Analysis 1: 36 samples/day
Analysis 2: 12 samples/day
Analysis 3: 5 samples/day
Analysis 4: 2 samples/day
Analysis 5: 26 samples/day
Analysis 6: 20 samples/day
Analysis 7: 12 samples/day
I’ve computed their taktime based on the net available time/day of: 26,100 sec/day. I need to come-up with the min and max no. of samples/day requirement with all the analysis to be divided into 4 analyst(workers) who will do the analysis stated above. I need to present all the 7 analysis in 1 yamazumi chart but I’m having a hard time what takt time to be used in the overall yamazumi chart. Thank you.
Hi Francis
Let’s start with some clarification (for me):
Does “samples/day” represent what got completed, or what was required?
Takt time should always be calculated based on incoming demand, not on production output.
So, how many samples were required each day, regardless of what got done?
Hi Mark,
The samples/day I’m talking about is the requirement/day.
I’m also confused if the Periodic/preparation time per analysis needs to be included in the yamazumi chart since it has the biggest contribution in a process, like for example
Analysis 1: Cycle time: 595 sec/sample
Preparation: 1,442 sec
If i have a 36 samples/day, it’ll have a takt time of 718 sec/sample. Which is lower than the total cycle time stated at Analysis 1. Which indicates that I’m in need for additional manpower right? Thank you
Francis –
So are you saying that for one person to carry out all of the steps, you would need a total of 1442+595 = 2037 seconds, right?
If so, yes, that is your total cycle time.
If your takt time is 718 seconds, then you would need:
2037 / 718 = 2.8 (rounds up to 3) people to keep up with that rate.
IDEALLY, you would divide up the labor into “chunks” of 700 minutes or so, but you can’t always do that.
This is theoretical.
In the real world, there are a couple of other things to consider.
There is very little margin for error, rework, delay, etc. in these numbers which is likely why you have 4 people today. That extra worker is there because you have unsolved problems.
We would typically cut the takt time by some margin to account for those unsolved problems and actually solve the people calculation to that.
For example,
718 seconds * 0.85 = 610 seconds.
If I took your total cycle time of 2037 and divided that by 610, instead of 718, then you would need 3.4 people, which likely more accurately reflects where you are today.
Does this make sense so far?
Hi mark,
With regards to your post on no.130, It is now clear to me that total cycle must be used in the yamazumi. But I’m confused with the data,
1st, the 2,037 sec total cycle time with takt time:718 sec which is theoretically must be divided into 3 workers. Thus, in actual, it is done by only 1 personnel and the Analysis A is only a part of his whole job cycle which include Analysis B and C. In other words, the worker that I’m talking about has other jobs in addition to Analysis A. Thus, the worker manage to comply with the demand even though, theoretically, it cannot. Is is really possible?
Mark-
I’m working in a medical environment and I am struggling with how to show the PCP (Primary Care Provider) cycle time – specifically:
I have good cycle times (based on actual observations) for the PCP chart review, medical exam and post visit chart update. The cycle time for this is 31 minutes.
The takt time is one hour/patient and customer demand is 6.7 patients/day.
The problem is how do I show the fixed work done after all patients have been seen – PCPs receive many “alerts” per day & PCPs generally save this work for the end of the day (batch). The average time spent by PCPs on alerts per day is 2.5 hours or 37 minutes per patient.
How do I show this in my value stream map? Do I include a process box for the PCPs to show this alert processing time, the PCPs would then have two process boxes one for batch and the other for the routine patient visit, or do I just add the avg. time/patient (37 minutes) to each cycle time ( 31 min + 30 Min)?
Any assistance would be greatly appreciated.
Hi Bill –
As I understand what you are saying:
Your PCP sees patients serially during the day, taking 31 minutes per patient.
For each patient the PCP sees, s/he takes an additional 37 minutes at the end of the day for “alerts” processing.
Is that about it?
Mark-
I apologize for the confusion and very much appreciate your response to my question.
The day I observed the PCP she saw 8 patients. Her patient load/day can vary from 4 to 9 per day. The PCP also receives approx. 140 alerts/day plus frequently answering secure patient messages and holding a telephone clinic with patients. The PCP estimates she spends approx. 3.6 hours/day on answering these alerts, secure messages & telephone clinics. The patient cycle time is 31 minutes to see the PCP, as stated above. I divided the 3.6 hrs for alerts etc by her patient load for the day (8) & came up with 27 minutes. Should ths 27 minutes be added to the 31 minutes for the patient cycle time? If so this would give a cycle time of 58 minutes, close to the calculated Takt time of 63 minutes/patient. What I am not sure about is the way I calculated the impact of the alerts, secure messaging etc by using her daily patient load – what this the right way? If so it will vary daily depending on the number of patients. The time for daily alert processing, secure messaging is done after the PCP sees all of her patients.
Thanks again for your assistance and patience.
Bill
The purpose of takt time is to give you a “should be” condition to strive for and check against.
Aside from calculating takt time, what are you striving for here? What is then overall challenge you are trying to meet? (What experience do you want the patient to have that they are not getting now?)
How you set your takt times will depend quite a bit on this.
Mark-
The problem comes when analyzing the workload for the PCPs, specifically the time required to answer their daily medical alerts. After the PCPs see their patients they spend the remainder of their shift answering alerts which frequently takes an additional 2 or 3 hours. This extra time exceeds their 8 hour shift (an emotional issue for the PCPs).
My question is how to capture the PCPs extra work in the VS? Where should the time the PCPs are spending answering alerts be captured – as part of the patient cycle time or included elsewhere?
Once again thanks for your assistance.
Bill
Bill –
Your description of the problem as how to analyze the workload is very common.
The REAL answer to your question might well be “it depends” (and that is what I think it is).
However, without any other context, my first instinct would be to treat “seeing patients” and “responding to messages at the end of the day” as two separate tasks. If you do that, then you would take the time spent “responding to messages at the end of the day” and deduct it from the available time for “seeing patients.” That, in turn, is going to cause your takt time to speed up, but that reflects the reality of what you have today for your current condition.
Now… if your cycle time to see a patient exceeds the takt, then you have a couple of levers you can pull. You can work to reduce the time your physician has to spend dealing with each patient (but please remember the perspective of the patient and not cut that face to face time to do it). And / or you can work to smooth out the “respond to messages” tasks so they take less time, creating more time to allocate to seeing patients.
BUT…What I would like you do is step back and tell me “What are you trying to improve?”
What is the overall challenge or direction?
What result(s) need to change, in what direction, and if you know, by how much?
What does the operation need to be able to do that, today, it cannot?
I am asking because the overall direction you are trying to go will have a significant impact on the approach you should take.
You might also want to breeze through this old post you may not have seen:
https://theleanthinker.com/2008/01/29/mura-muri-and-muda-in-health-care/
and this book review which seems germane to what you are working on:
https://theleanthinker.com/2009/06/26/follow-the-learner-dr-sami-bahri-dds/
Key Point: What you are trying to improve has a large impact on what “current condition” you are trying to capture.
Hello,
This thread was a great find & I appreciate the discussion. I work in a hospital, and we want to reduce patient waiting times for outpatient laboratory services. I’m trying to apply principles of cycle & takt time to understand how many staff are needed to meet customer demand/expectations. We have a morning surge of demand for ~2 hours, which then drops off. Does it make sense to think of these 2 hours as having their own takt time, distinct from the rest of the day?
Thanks
Ted –
The short answer to your question is “yes.” It is completely appropriate to adjust staff levels to expected loads. Just look at any McDonalds.
The longer answer is you would probably find this book very germane to what you are working on:
https://theleanthinker.com/2009/06/26/follow-the-learner-dr-sami-bahri-dds/
Hello Mark,
I’m undergoing a manufacturing programme, a task was given to me to fine the approriate cycle time without any information on required unit of production. The given table is like;
Task Time (s) Predecessor
A 20 F
B 12 –
C 45 D
D 60 A
Sixtus –
Without any units or context, your table is just letters and numbers.
What do they mean?
Thanks Mark.
Yes I agree with you. I planning to assume required unit of production and time.
Sixtus –
I mean what does “A 20 F” or “B 12 -” mean?
A is Process Identification, 2o sec is the processing time while F is the immediate predecessor to A.
OK, so it seems (from “F is the predecessor to A”) that there is a process cycle of some kind here?
F for ?? seconds then
A for 20 seconds then
D for 60 seconds then
C for 45 seconds then ??
What is the task time for F
What comes after C?
All in all, though, it looks like your “unit of work” could be once around the cycle. You are only talking about two or three minutes as a pitch time then.
As newly appointed Manager please suggest how to manage this below situation
Scenario:
the company is currently producing 40 pcs per shift where it used to produce 56.
Hourly output is unstable without clear reasons.
The scrap level have increased
factory currently run on 3 shifts (120pcs a day)
Actual demand is between 100 to 110 pcs per day and demand will increase to 140 per day in 3 months’ time.
There is pressure within the business to reduce manning from 5/shift to 4.
Kingsly –
Your situation sounds challenging.
Your first challenge is to get down to the shop floor and carefully observe and measure what is really going on.
There is a good guideline for that here: http://www-personal.umich.edu/~mrother/Materials_to_Download.html
Look specifically at “Direction and Challenge” and make sure you are working on the right thing. You probably can’t fix everything at once.
Then really spend time with “Grasp the current condition”
Those two give you enough information to understand what must be done.
If you want more specifics, hit “Contact Mark” in the right sidebar —->
and we can discuss your exact situation.
How do we manage the seasonality in production volumes using Takt time? Here in our industry we have very high seasonality in peak season we have 300 Mc per month and in lean season we have 100 Mc per month.
How do we manage manpower? Pls suggest.
IA –
This is a common problem, and is getting into the area of production planning and leveling, which is a bit beyond the discussion of takt time.
The answer, unfortunately, is “it depends.”
It depends on the business issues. In principle you want to smooth out production changes as much as you can.
Other things some companies do is design right-sized (and less expensive) equipment so they can add capacity incrementally.
If the process is mostly labor dependent, many businesses hire seasonal workers or work longer days / weeks during peak seasons. That depends on the flexibility of the workforce, and the company culture.
In some cases, it is possible to build ahead to reduce the peaks and valleys.
Other companies seek to expand their product line into other seasons. A classic example of this is Just Born Candy, the makers of “Peeps.” Their business was centered around Easter, but they have expanded their product line to include other holidays.
If you want to discuss the specifics of your situation, hit “Contact Mark” in the right sidebar —->
and email me.
How is No. of pitch / workstations calculated in a manufacturing line ?
Calculating Number of Workstations on a Production Line
The principle is pretty simple:
How Long Does It Take To Build It / How Often Do You Have To Finish One
Example:
It takes about six hours to assemble an automobile.
That is 6 x 60 = 360 minutes.
They need to complete one every minute. (Takt time)
That means the line needs to be 360 vehicles long.
“How long does it take to build it” is going to largely be based on what has to be done.
On a small item, only one person can work on it at a time, “how long it takes to build it” is the same as the SUM of the operator cycle times + any dead time moving between stations.
On a larger item, many people might be able to work on it at once, so you will need to look at the assembly sequence, interference, dependencies, etc. to determine the overall flow.
Takt time is defined as “Available Minutes for Production / Required Units of Production = Takt Time”. In his book, Gemba Kaizen Masaaki Imai defines takt time in a parenthetical as “the time it takes to produce one unit”. (p. 8 kindle version)
In my opinion, jargon is muda if it doesn’t have a consensus meaning. There is a good deal of discussion about “available minutes” but i’m more interested in the number of “required units of production”. Required by whom? How is it calculated? If I have orders for 50 widgets does that constitute “required units of production” and doesn’t it all constitute demand. If my available time is 453 minutes, my takt time is 9 for those 50 units. (453/50) If I have orders for 500 units, is my takt time -.91. How does that help me other than saying I don’t have sufficient capacity? If I have 100 orders for 50 widgets , how do I determine the required units of production? If I have 100 orders of 50 widgets and 50 gidgets, who do I determine the required units of production?
I am much more interested in “drop time” –at what interval will a unit be completed? If I know my capacity (available minutes for production?), I can calculate how many units I can produce in a given time. The “drop time” is also a standard. I can measure production based upon whether I am meeting the standard “drop time”, and it provides a measurement for improvement.
What are your thoughts?
Jon –
I think your “drop time” is the intended use of “takt time.”
The reason the lean community puts so much emphasis on “customer demand” in the denominator is a response to a tendency for many industries to have overproduction as a matter of policy, and set capacity to put product into inventory.
Absorption cost accounting drives a lot of this behavior – the company produces product to “absorb overhead” but doesn’t actually have the demand to support that production rate. Or worse, given actual demand for Product A, they make Product B instead to avoid setups or because they can make Product B more efficiently, so they get more “credit” for that. And yes, there are large, well respected companies who do exactly this – stuffing warehouses with Product B, running out of Product A, and declaring large EBIT based on the asset increase on the balance sheet. All because they made product to match their capacity.
“Customer demand” can also refer to an internal customer.
A back shop can perform operations that support a number of value streams. They must calculate their takt time based on the demand they are expected to meet.
Hopefully the production control function has made some effort to level the production system so they are protected from huge swings in “demand” that can be artificially created by large batches and single reorder point demand signals.
As far as the semantics are concerned, I don’t think we are ever going to have a universal word that is accepted by everyone. The key is that the people in a particular organization know what they mean when talking to each other.
Thus, I am perfectly happy talking about “cycle time” in the “total lead / response time” definition with a client that has been using that term for decades. There isn’t in value in trying to change their internal jargon. I’d rather spend the time focusing their attention on how to reduce it dramatically (which we have done).
Thanks Mark, for your reply.
May you pls tell me one more thing.
If I am evaluating a task which needs two operators wherein I need 2nd opeartor in small intervals. so 2nd operator is working but based on first operator sequence.
How do I evaluate the run hours?
IA –
I am not sure what you are asking, but I’ll guess.
How do you evaluate the run hours? I’m not sure, because I’m not sure what you mean by “run hours.”
If you mean the total operator cycle time, then “How long would it take ONE person to do the job?”
Your question implies you have an operation with a cycle time slightly greater than your takt time.
Thus the calculation for people required:
(Total Operator Cycle Time / Takt Time) ends up slightly greater than 1.
The challenge in this case is to improve the work cycle until one person can get it done.
It’s always a pain to calculate cycle time properly with a classic stopwatch, that’s why I decided to make this simple app for automation engineers like us. (link: https://play.google.com/store/apps/details?id=com.avafab.cycletime)n
Hi,
I want to give Target Quantity to my operators for their shift. How to calculate how much can they produce? I have an automated system for displaying them such information !
Sid:
The way the math works is:
1) How much do you need to produce each shift? Determine this in terms of time / unit. This is your takt time.
2) Apply a bit of overspeed to the takt time so you can make up for variation and problems. How much depends on the situation. I’ll use 15% for the exercise. So – take your takt time, and multiply by 0.85 to get a slightly faster time / unit requirement. This is your planned cycle time. It is the speed you are measuring performance against. Your output cycles should strive to match this.
3) How long does it take to produce one unit. This is your operator cycle time, or total labor content.
4) Divide your total operator cycle time by your planned cycle time. For example, if it take 4 minutes to build one product, and you need one every 2 minutes then 4 minutes / 2 minutes = 2 people required.
If you need more people than that to succeed, then there are problems you need to work on. That is where you apply daily improvement.
You can see from this that you don’t start with an arbitrary number of people and give them a quota and just expect them to meet it. You have to study the system, and fully understand what is required, then determine how many people are NEEDED.
If that number is too high, then you need to do something about the work content and variation.
Hi Mark,
I am actually doing on a project which consist of Lean Six Sigma. The company we are focusing on do precision welding.
1)We are not sure how do we arrive to USL or LSL for Gage R&R. We are doing Gage R&R to measure the accuracy for time observation in the workshop.
2)For value stream mapping,
Problem faced
– the company engage 3rd party based on the customer preferences in some process.
Do we consider the 3rd party to be a supplier?
-Cycle time
We took a sample of 20 data from each station. Do we take average cycle time for 20 data or do we just take any one of it?
Does this apply to changeover time too?
-Steps in the VSM
On the welding process, we realise there are different steps depending on the customer requirement. How do we deal with the steps?
– After mentioning the above, are we still able to proceed in working out the takt time?
Available resources:
-Worker work from 830-530 (Exclude OT to maximum till 9)
– There is only one shift 830-530
– Total break is about 75mins
– There are no compulsory work they have to finish in one day, some welding might even take up to several days.
Please help me. I’m really lost and I appreciate every piece of information you could provide.
Mavis –
1) Gage R&R should have nothing at all to do with measuring time observation, unless you don’t trust your stopwatch.
2) Value stream mapping:
– How you map your 3rd party really depends on the flow of material and product to and from them.
– For cycle time measurements in value stream mapping, I would document the range of variation, and the lowest time that the process can repeat without special circumstances. Same with changeover times. If there is a lot of variation, that is valuable information for the “Current State.”
– Welding operations: If there are different steps that all take about the same amount of time, then I would call it “welding” at a VSM level. If your customer requirements introduce significant differences into the flow, then I would show a diversion of some of the product. The part of the value stream where the process splits would have a separate takt time for each branch.
– Takt time is calculated, and sometimes is local. See this post: https://theleanthinker.com/2010/05/21/takt-time-is-local/
– Available resources: I’m not sure what you are asking here. Your available time is 465 minutes based on the numbers you gave me. If your workers don’t know what needs to get done, then it is likely management doesn’t know either.
Hi Mark,
I am really thankful that you replied to my enquiry.
I still have some doubts in certain process.
You said that Gage R&R is not necessary in taking down the time observation.
However we got three person taking the same data, using different devices like stopwatch and mobile phone.
We are only doing this time observation for 1-2 months. Is Gage R&R appropriate to be use for measuring the accuracy of our time observation data?
2) Can Process capability be used for cycle time?
So for cycle time and change over time i just have to take lowest time to be place inside the VSM description box?
Thanks a lot (:
Mavis –
I don’t see your cycle time collection variation as a gage R&R problem. You simply have inconsistent process execution. If three people are carrying out a task three different ways, you aren’t going to get consistent results. Gage R&R is a process for calculating the variation inherent in measurement, usually applied to a quality issue.
For value stream cycle times, it is more likely your people don’t do it the same way. For a value stream map, it is unlikely a few seconds one way or the other for cycle times is going to make a difference, unless your takt time is VERY quick (under a minute).
I would highly recommend you download Mike Rother’s “Improvement Kata Handbook” (http://www-personal.umich.edu/~mrother/Materials_to_Download.html) and pay particular attention to the techniques for cycle time collection in the section titled “Grasp the Current Condition.” That will likely help you get some insight.
Hi Mark, I am working on a final year project. I involved in an Assembly Process that produces 1.1434units/day at a Takt time = 14hours/Unit. That is 22 Units per calendar month @ 2 shifts of 8hours/day, 5 days a week. The Assembly Process has 6 workstations. One of the workstation is a potential bottle neck in the process with two Tools which take 4 hours each to assembly + other activities (drilling etc..) and then Tools are left on assembled to each unit for 12 hours to allow the adhesive to cure, that is, for 16 hours/unit these Tools can’t be used. My questions are if we increase the number of units by 1, 2 or 3 per month, what Lean Six Sigma equations can I use to determine the necessity to buy a Tool/s? Should I consider a buffer or only produce what the customer requests without a buffer? And if I should consider a buffer what should it be or what assumptions should I consider?
If the Tools are more than capable of maintaining the capacity, how do you weigh the risks e.g. what if one gets damaged?
I believe 3 shift options are not an option. Should one only consider weekends if the cost having the factory open is cheaper than the cost Tool? Or should it be considered over a payback period? Thanks in advance.
Delores –
The math is pretty straight forward.
Your takt time is 14 hours.
Your cycle time for one tool 16 hours.
Cycle time / Takt time = # tools *required* to survive
In this case, 16 hours / 14 hours = 1.14 rounds to 2 tools required.
Solving for takt time, your 2 tools can support you up to:
16 hours cycle time / 2 tools = 8 hours takt time.
So as long as your takt time is above 8 hours, two tools will get the job done.
At an 8 hour takt, you will be removing a tool JUST as you need it on another part. Realistically, that is probably a bit tight, so I’d recommend using a planned cycle time that is about 15% faster than your takt in reality.
What about if one gets damaged?
You can use the same math to calculate how much time you would have to repair a damaged tool.
Think of it this way:
I apply a tool.
14 hours later I apply the 2nd tool.
Two hours after that, tool #1 becomes available.
You don’t NEED it for another 12 hours though.
As your takt time approaches 8 hours, your safety margin approaches 0, because at that point you need the freed up tool right away.
NOW… if you aren’t actually building to takt, meaning starting a part every 14 hours, then things can get confusing. That is one reason to pace the system – so you can calculate AND USE the inherent buffers it gives you. If you aren’t doing that (pacing the system to the takt time), then you are seeing how overproduction can hurt you by using up your bottleneck capacity before you need it.
Hi Mark,
I would like to ask question on some tricky problems for my project.
I am working on a company that repair product, the product can come in any time on daily/weekly/monthly basis to be repair.
The customer dateline are random, they dont have any fixed date, some of the dateline are given by the company. Eg. Product A can be given 2weeks to repair, Product B can be given up to even 1 month to repair. So they are not constant.
I wonder is it possible to calculate the Takt time? What information should i collect?
Are there different takt time to different process in repairing?
Eg. Inspecting/Cleaning ?
Available time : 465mins (exclude breaks)
please help, thanks .
Hi Eric –
I am working with a client that does repairs right now, they have the same questions. 🙂
First, keep in mind that takt time is a tool for managing the progress of the work vs. the expected progress. Because it is a unit-by-unit measure, takt time vs. cycle time provides much faster warning that something is taking longer than it should. This allows the leaders to get out in front of problems more quickly.
It IS possible to calculate takt times for repair operations. What is tricky is how to manage leveling the demand. As you likely know, the more level you can make the load on the shop, the less excess capacity you need to carry to cover the fluctuations.
For calculating takt time, the customer’s due date is not that relevant. The question is “How many units do you need to complete each day to keep up with the overall rate of customer demand?”
Different due dates would be factored in to determine the next unit to START, but you want to set up your production system to work at a steady pace, with no queue jumping, with as little excess WIP as possible.
So… the question is “How many units do you need to complete in 465 minutes to keep up with demand?”
Hi sir,
I am having probem getting the capacity of machine. I would like to ask how to get the machine capacity?
for example i have 5 samples in a certain machine. How will i compute the capacity per
shift ? working hours per shift is 7.25 only
1. 32 sec
2. 32.12 sec
3. 31.94 sec
4. 32.24 sec
5. 32.64 sec
Markee –
There is less than a second between your cycle times. If you are using a manual stopwatch, I’d guess most of the variation was caused by your fingers.
Taking your longest time and rounding up to the next second would give you a cycle time of 33 seconds.
It is far more likely that your capacity will be impacted by time the machine is not running, or not running at full speed.
What is your quality fallout?
How much time do you spend in changeover?
How much time is the machine simply not running for breakdowns?
How about programmed maintenance?
Does it always run at full operational speed?
All of these things will affect your capacity.
IF the machine were running 100% all of the time, then the calculation is relatively straight forward:
7/25 hours * 60 = 435 minutes
435 minutes * 60 = 26,100 seconds available.
Divide that by 33 and you get about 790 cycles available.
But there is going to be downtime.
Let’s be optimistic and say that you lose 15% of the capacity to losses, etc.
That leaves 22,185 seconds.
22,185 seconds of run time / 33 seconds of cycle time = 672 cycles during your 7/25 hours.
BUT… I would imagine your up-time is nowhere near 85% so you probably want to use more accurate numbers.
Has anyone tried this Android App for Takt Time? http://www.taktcompany.com
I wouldn’t suggest jumping to an automated tool without first mastering taking cycle times with a simple continuously running stopwatch. A “time observation study” is 1/3 about “time” and 2/3 about “observation” and “study.” Have you observed the cycle to get a feel for it first? Picked a clear observation (start/stop) point? Do you have a way to record out-of-cycle work, or other anomalies when they occur?
Maybe I’m old school, but by writing down the numbers, I have to pay attention to them, and get an opportunity to do a sanity check before I accept them as an accurate representation of what happened.
As an aside – the owner of the domain linked above has obscured all of their contact information from WHOIS through a Panamanian registrar. There is no way to contact them except through a link on the site. The APP is very new, and has very few reviews. I’d, personally, hold off before blindly loading it onto my phone and running it, but that’s just me.
Hi Mark,
Thanks for your response, what I was looking in this app was the export of the time results to an excel file, since most of my work and analysis is done there. I downloaded the app and it works pretty well. I understand when you say that you have to pay attention to the numbers and it concerned me too, but the app has like this preview history meanwhile you are taking time, maybe it sounds like I’m selling the app, but yesterday and today has work great for me and has saved me a lot of time on working with the results. Let me keep testing this and I will be back later to let you know if it is a good choice. By the way, great blog!!
Hello Mark, mi name is Guillermo Gomez, not only I’m a follower of your blog (I work as a Continuous Improvement Coordinator in a Manufacturing Company) but also I am one of the cofounders of Takt Company, the tech startup behind Taktiming, an app whose link got published here yesterday.
First of all, I’d like you to thank you about your feedback.
Regarding the obscured website WHOIS, we didn’t thought it may create distrust; we will change this immediately and eliminate this WHOIS blockage.
About ourselves, we created this app Taktiming, which is new, it got published 2 days ago, and we created this Company, a couple of months ago, as a way of helping industrial engineers, kaizen practitioners or anyone that uses Lean or TPS on a daily basis. We wish to eliminate non-value added processes and this app, we think helps. Taktiming, is our first proposal we are looking into creating more IT systems to support every day’s continuous improvement operations.
We don’t intend to reduce or replace the observation stage of any time measurement, we think is the most important part of any continuous improvement process, you have to know where you are standing, which is the current situation and then once you fully grasp this, you can begin thinking about optimizing your process.
All we wish is to be given an opportunity to show the value of our app, help people who normally take continuous time measurements and continuously have to rewrite from paper to a computer all their time measurements, using time that could be better used by observing the process or analyzing results.
Again, I thank your invaluable feedback and we will immediately take action with this WHOIS matter.
Regards,
Guillermo Gómez
Guillermo –
No worries on the web site. From my side of the screen, I get a SPAM:comment ratio of about 200:1. Now and then one slips through the filters, and I have to check out any links in it to make sure they are legit before approving it. At the same time, I was looking for evidence of “astroturfing” – a shill user promoting a product on behalf of the company, pretending to be a “grass roots” user. So I wanted to run down where everyone was from (You and Coke’s IP hosts are in the same city, by the way.) If you’re going to have a web presence, it’s good to learn a bit about how the Internet works, by the way.
As for the application, I’ve seen these before. If people find it useful, then great.
Now back to the discussion(s) about cycle time and takt time. 🙂
A Lean Practitioner
Dear Sir,
Please notify to my mail id regarding the new questions along with answers regarding the lean production
Hi,
One more question, now we are trying to implement a program to reduce the changeover time between two batches. However we need to know when the batch will complete, i.e. the time of the batch completion. What would be the most accurate way of calculating that ?
Sid –
It’s pretty simple. Once the run starts, what is the cycle time for one piece (from exit to exit)?
Multiply that times the batch size, and you’ll get the run time.
I have a question. We are implementing takt time in a medical facility, it has been a challenge in that there are many variables involved with taking care of a patient- and each patient is different. Are there any medical facilities that have implemented takt time successfully that I can perhaps talk with. I really want us to be successfully in this area but it seems impossible when we are dealing with actual people and procedures.
Pearl –
The first question I have is “Why are you trying to implement takt time?”
I am not saying it won’t work, but rather, want to be clear on what you are trying to accomplish with it.
What problem(s) are you trying to solve?
Dear Sir
Thanks for your mail. You again amazed me with your great mind. Thanks
Situation 1
I have 10 Stations,
station 1 to 4 cyc. time 1 Min batch qty 1 No.
station 5: baking batch qty 30 Nos., Time 30
Station 6 to 10 : cyc. time 1 Min batch qty 1 No.
( In order to avoid waiting, before and after station 5 I have 30 Nos inventory.
The Question
When I calculate the lead time how should I count the cycle time of baking station?
Is it as per scenario No. 1? Or Scenario No.2 or Something else?
Is it right to take average of inventory time or should I take the worst case?
Scenario No. 1: station 5 cycle time calculated as 30 Min/30 Nos. = 1 Min, so my lead time is
Station 1 to 4 = 4 Min
Station 5 = 1 Min
Station 6 to 10 = 5 Min
Lead time = 10 Min
Scenario No 2 :
Station 1 to 4 = 4 Min
Inventory = 15 Min average ( First piece 30 Min, last Piece 1 Min)
Station 5 = 30 Min
Inventory = 15 Min average ( First piece 1 Min, last Piece 30 Min)
Station 6 to 10 = 5 Min
Lead Time = 69 Min
Thanks in advance for the reply
If you are trying to determine lead time through the system, just time one unit from start to finish.
But remember, you are including the WAIT times in your lead time.
So the product that arrives just as the oven door closes is going to wait 30 minutes BEFORE it can go into the oven.
Downstream of the oven, once you take the batch of 30 out, they are going to wait in a pile there as well.
IF you have good flow, your lead time through the oven is 2x the oven bake time.
(30 minutes in the oven, an average of 15 minutes on either side of it)
But don’t try to do this mathematically. First, put some paper on a table, draw squares to represent each of your processes, get some coins, and move them “through production” in simulation. Understand the actual dynamics of what flows, what waits, and why. Once you have a good visualization of what is actually happening, the math is easy to figure out.
Dear sir,
I have a question . I would like to discuss that in detail. I am serving in Atlas Honda. My all questions are related to the buffing shop of our manufacturing plant.I want to calculate the capacity, Takt time, cycle time and required number of machines to achieve the given target. There are multiple products which will be buffed in our shop.
Daily plan for product A = 1615 sets
Daily plan for product B = 1666 sets
we have just 5 machines and we are working in 2 shifts
Total time for a single shift = 575 mins
Lunch break and 2 tea breaks = 60 mins
Available time becomes= 515 mins
I am confused that on average how much time should we take for set up time, break down time, Worker’s fatigue allowance, Re-working of defected parts,start up time , closing time, non-working time etc ( Buffing is an operation done on machine by a worker manually)
For product A four operations are done on two machines ( 1 machine is having 2 stations)
Machine no.1 = 120 seconds
Machine no.2 = 140 seconds
For product B six operations are done on other three machines and time taken is
Machine no.3= 60 seconds per set
Machine no.4= 20 seconds per set
Machine no.5= 18 seconds per set
kindly tell me about the feasibility of this project,required number of machines, takt time etc with working that will be easy for me to understand.
Thanking you in anticipation.
Hi Fahad –
Just to check that I am understanding correctly:
You have 515 available minutes per shift
x 2 shifts = 1030 minutes of production time.
That equals 61,800 seconds.
You have to produce 1615 units of “Product A” in that time.
61,800 seconds available / 1615 units = a takt time of ~38 seconds.
This means you must complete one Product A every 38 seconds to succeed.
Where I am unclear is your cycle times.
If I am reading this correctly, every Product A must go across each of these machines.
Each Product A must spend 120 seconds on Machine no. 1;
then spend 140 seconds on Machine no. 2.
If the above is true, you can only complete a Product A every 140 seconds.
Can you tell me what I have wrong here before we proceed?
Nothing wrong sir … u have got my question …. Actually to have finished product A we have to work on both machines after that we are getting a finished product and similarly for product B we have to process that on three machines ( Machine number # 3,4,5 ) then we are getting finished product . Sir one thing more how we can take 515 mins as our E.O.T ( Effective operating time ) without subtracting time wasted on set up, change over, daily meeting , closing, Down time etc… what percentage should we take of 515 mins as per standard?
Fahad –
If the math I showed you is correct, then there is no point in discussing how much more time you can allocate for anything.
With 100% of your 515 minutes devoted to production, you only have 61,800 seconds of total time available.
If your bottleneck process for Product A takes 140 seconds, the BEST YOU CAN DO, even devoting 100% of your 515 x 2 minutes to production would be 61,800 seconds available / 140 seconds cycle time = 441 units of production. If my math reflects your situation, you can make less than half of your requirement with NO changeovers, NO downtime.
Hello sir,
I’m working on a project whereby the cycle time used to be 16.8mins, this is with 4 operators. the demand for units was 15 per hour giving a takt time of 3.44mins (an hour here = 51.6mins not 60mins as we gave 14% allowance for fatigue, toilet etc). From above, it can be seen that each operator is around 4.2mins (16.8/4). Which is greater than the takt time
However, the demand has now gone up to 18 units per hour changing the takt time to 51.6/18 = 2.86mins. Using 5s principle and so on, we have managed to reduce the cycle time to 11.5mins so each operator is now 11.5/4 = 2.875mins which is now less than the takt time.
My question now is, are we on the right track? And also, if cycle time / take time = number of operators/stations, should we carry on four operators (11.5/2.86 = 4.02 operators). The reason I’m asking this is because, the company is thinking of changing to three operators instead of four but i need to convince them to stick with the initial 4 operators.
Thank you
ife –
Yes, you are on the right track.
If your cycle times are accurately measured, there is no way that three operators would be capable of working fast enough to meet your demand until you found enough improvements to reduce the total cycle time to under 3x takt time.
It would be appropriate for management to challenge you to GET there, but it is going to take time and improvements to cut the work by more than 25%.
Hello Mark,
I am trying to do a VSM of an inspection process. The process have 8 steps which are performed by a single operator. How can I represent the operator in each step of the VSM without making it seem that there are 8 different operators?. Also, How do I calculate the up time for each step? Thanks in advance.
Hi Ross –
I don’t think the VSM is the appropriate tool for what you seem to be trying to do.
At the level of a typical VSM, there would be one box labeled “Inspection” with a single operator, a cycle time, etc.
If you are looking to break down “Inspection” I’d suggest taking a look at Mike Rother’s “Improvement Kata Handbook” especially the section on “Grasp the Current Condition” That is more geared for the detailed process level.
The VSM is a tool for “Grasping the Current Condition” and “Establishing the Next Target Condition” of an entire value stream – in your case, likely the entire dock-to-dock flow.
BUT! be sure to understand the importance of the surrounding context, especially “Understand the Direction and Challenge.” Establishing that direction and challenge for the Inspection Process is an appropriate use of the Future State VSM.
Hi Mark,
excellent post on TAKT time. Currently, building a VSM on loading, transporting, unloading sand from semi’s to railcars to be shipped to customers.
As our customer requirements differ on every order (different sand grades, amounts, eleventh hour orders) we do not have a standard for shipping as we are flexible and able to accommodate every customer.
Likely processes will be:
1: Loading from factory( factory>semi)
2: Trip to Railcars
2.5:(There is a wait time here)
3: Unloading( semi>Transloader>railcar)
4: Return trip
The wait time at 2.5 is caused by other semi’s that are currently there unloading, human/transloading delays, improper time management/coordination between semi’s, unavailble railcars, etc.
Would the 5 processes I’ve identified be ideal or is there anything else that should have been included I’ve left out?
I appreciate your help.
Thanks again.
Regards,
Donavan
Donavan –
Let’s start with a stab at your takt time:
It looks like your unit of work is one semi-load at a macro level.
Regardless of variation in how many semi loads are in a particular customer order, I’d *guess* that the time to cycle a semi is (except for wait time) pretty stable.
How many semi-loads do you *expect* to be *able* to transfer over the course of a day?
You are right.
Currently focusing on the troubled process in the overall.
We accommodate a few customers at once, and the orders vary daily.
Data:
– 12 hour shifts.
– 4 semi loads per hour.
– load per semi = 26 tonnes
– load per railcar = 115 tonnes
– loads per day = 2400-2500 tonnes
Semi requirements:
– 6 loads/shift comes down to 1 load in 2 hrs.
– 4 semi loads per hour (15 mins – time taken to unload semi to railcar).
Cycle time per semi-
LOAD at BASE: 5mins
TRIP to RAILCAR: 50mins
UNLOAD: 15mins
RETURN to BASE: 50mins
TOTAL = 2 HOURS
Donovan –
Parsing your information, it looks like your takt time is 15 minutes… meaning IF you had a level workload, you ideally would have a semi arrive to be loaded at base every 15 minutes, and departing on its two hour cycle. Since this math says you need a *minimum* of eight semis, and since you said you have a lot of variation in the work, I’m guessing you have a dozen or so trucks in work at any given time.
Your tasks or LOAD; TRIP TO RAILCAR; UNLOAD; RETURN are a pretty good block diagram.
Where do trucks accumulate? How many are engaged in each of these tasks at any given time?
And, at a higher level, What problem are you trying to solve?”
What results need to change?
Do you need to operate with fewer trucks?
Are deliveries late?
What is the primary problem you are facing?
What we aren’t yet looking yet is “What could we improve?”
Rather, we are asking “What results must I achieve that, today, I cannot?”
That question actually precedes the discussion about takt time, but I’m beginning to understand more about what you are asking about.
Mark, yes absolutely right.
Doing my best to inform upper management that it’s not more trucks that we need as he’s convinced that we need more. It is good to put it in paper so I have something physical to show.
Thanks for the advice and I really appreciate the post. Gained a lot of good info. reading the comments too!
Issues:
1.They want to buy more trucks. (when that’s not the issue and we have more than 8 cars for every location we loadout.)
2.The wait time to loadout trucks to railcar. (employee and equipment issue. May need an additional transload and employee)
3. Railcar not available at scheduled time. This is usual, so we have to be on-call. (These are out of our control as rail-lines run by state/federal and estimation given is inaccurate)
*transload = equipment to transfer sand from truck to railcar.
Primary goal is to fix errors first, improve performance, speed and better employee management second. Focus on immediate
1. I will have to address the errors first – high wait time due workforce and transload malfunction.
2. Next is on how to improve the process – add a second transload, improvise the conveyer on transload to load fast and more.
“That question actually precedes the discussion about takt time, but I’m beginning to understand more about what you are asking about.”
-I do agree, and I apologize if I went off a tangent.
Marvelous article! You have taken the pains to address the issue from a common man’s perspective.
I have 2 basic questions :
1)how do you define “customer demand” where there are no contracts with any customers and they come and go as per their requirements. Should we take previous years gross sales(even thus caries from year to year)? Or the installed capacity of the plant? Or what.
2)what if we level the production, and one of the products made therein does not sell at all for weeks or months?
Sharma
Sharma –
The “customer demand” number is often an estimate. Essentially you are deciding on the daily capacity of your system.
“Leveling production” does not mean blindly setting a schedule and producing to it. You always keep a careful watch for demand (or production) that is different than your plans and expectation. The “Plan” (or the standard) is used as a baseline to compare against reality so you can respond accordingly.
See The Importance of Heijunka for a discussion about leveling. The smoother you can run production, the less excess capacity you need to maintain to handle fluctuations.
All of this is something you strive for. It is not a stable system. Maintaining the balance is more like riding a bicycle. You are making constant small adjustments to keep things running as smoothly as possible.
Hello!
I am currently doing my master’s thesis on a hose production company. In the construction of the current VSM I came across a problem in relation to takt time / cycle time.
The VSM relates to production of a specific hose 25 meters (1 unit = 1 hose 25 feet) and passes through three processes.
In the first process (mixing) the granulate is made of PVC compounds (material to be supplied to the next step) long and has a cycle of 18.41 sec
The second case relates to the extrusion line, mostly automatic process (machine time) and has a cycle time of 246.87 sec, 60 sec is time person.
The latter process is the packing, and as in the previous step is mostly automatic process with a time of 101.51 seconds cycle.
My problem came when I calculated the takt time. With an available time 8pm (28800 sec) per shift and a demand of 7.45 units per turn, takt time = 3604.66 sec which compared to the cycle time of each process is HUGE.
As the machines throughout the process are not only used in the production of these hoses and as I have no information about the time that the machines are occupied with this production, I decided to apply to the time available the percentage of sales of the product study (1:47 %) which gave me one now takt time = 52.99 s. Thus the problem reverts once the cycle time of the second and third process is much greater than the takt time.
I’ll have to calculate takt time otherwise?
As the processes are automatic its difficult for me to adjust production to takt time.
Have any suggestions that might help me?
thank you
Best Regards
João Almeida
João –
The thing to keep in mind is that takt time has nothing at all to do with the cycle of people of machines.
It is nothing but leveled customer demand. Don’t let the machine cycles confuse you when calculating takt time.
If your equipment is shared, you will have a lot of waiting time as your product (25 feet of hose) is waiting its turn.
Let’s start with that.
Yes, I may have explained wrong way. I spoke in machine and person time used when calculating the cycle time for each unit (25 meters hose)
When I say that the machines are shared, I do not mean they are doing two products at the same time. An extrusion line produces X meters of hose type A for a few hours (many units) and then stop, make some setup, and then it’ll be busy with the production of type B hoses.
Since I have no data on the time of use of the line for the production of A, can i affect the sales volume on the available time in the calculation of takt time?
Thanks
I understand what you mean by shared equipment. Don’t let that come into play for your takt time. It will be a factor for your production planning, which takes takt time into account, but doesn’t affect the takt time itself.
Takt time is nothing more than a capacity requirement.
Your actual capacity doesn’t come into it. How often MUST you complete a reel of 25 feet to meet demand?
Or, put another way, if you had a stack of reels at the end of the line, and the customer took one every takt time, how often would they take one?
I think I have realized now.
I cant change my takt time.
I must take into account for the cycle time calculation the time that the product A is waiting to be produced. Am I right?
João –
You originally mentioned you were building a value stream map of this process flow.
The waiting time for the product A would be in the inventory queue ahead of the shared process.
On a VSM, you primarily use the takt time to determine the total throughput time (door to door of the flow). By multiplying total WIP x takt time you get a good idea for how long things take to get though the pipeline.
But once you start USING takt time for improvements, you have to look at the local situation.
Here is the key: The shared process has its own takt time which is calculated from the TOTAL demand, of all products.
See this post: https://theleanthinker.com/2010/05/21/takt-time-is-local/
If you take that view, then the takt vs. cycle thing starts to make more sense.
Hi Mark
Ok, now I could understand.
As my problem arises in the context of a case study of a master’s thesis, like to have a book that I can support this principle. Could you tell me a book that approaches this situation?
Thanks
João –
If you are working on a value stream map, the baseline reference is “Learning to See” by Mike Rother and John Shook.
Depending on where you are trying to go with this, other LEI workbooks can be helpful, especially “Creating Continuous Flow” (the red book); “Creating Level Pull” and “Making Materials Flow.”
You should also look at Mike Rother’s “Improvement Kata Handbook” which is a free download here: http://www-personal.umich.edu/~mrother/Materials_to_Download.html
Michael Baudin’s “Lean Assembly” covers a lot of good material, though it is assembly centric, there are things in it that apply to everything.
The same author covers topics relating to machines and automated processes in “Working with Machines.”
Hi Mark,
i want to calculate actual manpower used vs. theoretical manpower based on the takt time. please consider the following, the machine has several unexpected down time, change over, and etc. also running over time and running less shifts.
Mike –
It is pretty simple. Calculate the people required assuming problem-free operation.
To give yourself a little headroom, use 85% of your takt time.
Sum of Operator Cycle Times / (.85 * takt time) = minimum # of people
Compare that number with the number actually required to get the job done.
Count overtime as fractions of additional people.
Take a look at the Improvement Kata Handbook, especially the section on Grasp the Current Condition for a look at the logic here.
HI Mark
I have a process 19 second cycle time and my takt time is 24.75.how i calculate the standard time. any software i can use to plot the chart for the entire line process . thanks.
stpoon –
1) A suggestion. Unless you are pacing your line to 100ths of a second, round your takt time down to 24.
2) You ask “How can I calculate the standard time?” What “standard time” are you trying to calculate? If you are looking for a planned cycle time (a realistic operating pace for the line), you can start with roughly 85% of your takt time which would work out to about 23 seconds.
3) You asked about software to plat the chart for the entire line process. Not sure what you are asking to do here.
I have a problem related to Takt Time. The process in which I am working have two production shifts. But we have different amount of people for each shift. I calculated the Takt Time and number of operators per station and the results were that we will need a total of 8 operators per shift, but we only have 6 people for the second shift. What should be my approach on this?
Rozannimd –
This is actually a common situation.
The next step really depends on how you did your calculation. It also assumes that your # of operators calculation was for manual work, not simply attending to automated machines.
If you calculated the takt time by taking the (available time for both shifts / the total expected production for both shifts) then your MATH is telling you that you actually NEED 8 people per shift. Under these conditions, you cannot realistically expect 2nd shift to finish their work.
If 2nd shift CAN get the same output, then why do you need two more people on first shift? (it means the cycle times you used for the calculations are wrong)
Before proceeding, I’d like to resolve the above with you… what really happens out on your shop floor?
component p/y – 470,000
Hours /day – 22.5
Days/year – 24
Availability – 85%
How to calculate required cycle time??
Subhash –
You asked how to calculate the required cycle time.
I am going to assume what you are looking for is how fast you need to run to actually achieve the required output.
That would require you to take your available time and multiply by your .85 availability, then use that as the basis for your time.
In the case you cited, you have to produce 19,584 parts / day.
You have 22.5 hours to produce those parts, so your takt time would be 4.14 seconds per part, IF your equipment were reliable.
But since your equipment is only available 85% of the time, you have to run faster. This likely means you have extra equipment – so you should easily be able to calculate what that excess capacity is costing you.
With that reliability problem, you only have 19.125 hours per day. Something is “stealing” about 3 hours per day from you. Your equipment is going home sick more than 3 hours every day. Therefore, everything else has to run faster to make up the lost time.
This new calculation would be a planned cycle time of 3.51 seconds.
Dear Mark,
First of all thank you very much for sharing your knowledge this way.
I would like to submit my problem, at work after working over and over on our VSM and after different DMAIC project we could optimize our Takt-time by 20%, which in fact can help us to increase our production to match our customer needs. I am wondering how to estimate the economical return for the improvement? is there any easy approach to calculate it? I used the opportunity cost of 20% of my global manufacturing cost. but I am not sure it convinces.
thank you in advance for your support
Alain –
A couple of things. First, you can’t “optimize your takt time.” Takt time is calculated from your customer demand. It is an objective requirement that has nothing at all to do with your performance.
Semantics aside, I think you are saying that, today, you cannot meet your customer demand, and you need to.
Then you are asking what is the return on the investment.
I would, in turn, ask “What is the return on meeting this additional customer demand?”
It that something the company wants to do?
If it isn’t, then stop.
If the company DOES want to be able to meet that additional customer demand, what is the ability to do that worth to you? How much are you willing to spend to be able to do that?
Now, take THAT number and stipulate that any solution to the problem has to come in under that amount.
You should not be using ROI to justify whether or not to improve.
You should be using it to determine if you have to explore a more creative solution to the problem.
How much improvement can you get for free? Have you looked at that?
I have yet to encounter a production operation that doesn’t have a double-digit percentage upside with the resources (people, machines, space, etc) that they have, they just have to make the choice to do some hard work to remove the obstacles AND manage it differently from that point forward.
Hi Mark,
Can you write something about (cycle time, formulas to plan/schedule work) for assembly line. Well I am working in the machining department and I was scheduling the work load for the machines, calculating the OEE of the machines and also working on lean process. Now I wan’t to work with the assembly process and calculate OEE and also do something on the proces improvement. First thing I was blocked with is how to calculate the takt time and how to calculate the output for assembly line? It was not difficult to calculate for machining as there is only one piece that is machined at a single time per machine but where as in assembly there are different stations and different parts to be assembled at the same time which is confusing me. Can you explain me with an example ?
Dharmic –
Takt time was originally conceived for assembly lines.
Take a look at the article. The takt time calculation doesn’t say anything about machines, or the individual positions.
It is simply the time interval between units of output.
What has to come off the END of your assembly line, and how often, to meet the customer’s needs?
Then your measure, and build a run chart, of the exit cycles off the END of the line. This gives you a sense of the entire line’s ability to meet the customer’s requirement, and the magnitude of the variation, waits, stoppages, etc, as seen from the perspective of the customer.
Then you measure the cycle time for each station, and do the same thing.
Each station must be able to consistently complete their work with a cycle that meets the takt time. The more closely it matches, the more efficient your process. But, if you are just starting out, I would target the PLANNED CYCLE TIME (how fast to operate each station) at something like 85% of the takt time unless you have additional data. (So, if your takt time is 100 seconds, I would want a work station to be able to cycle every 85 seconds or so if they are problem free. That builds in a bit of overspeed for problems.)
You will have to decide where you are going to decouple stations of the assembly line from each other for line stop buffers. That depends a lot on the nature of the line, so I can’t give any specific advice there. Short lines really don’t need that, but long ones do. Even Toyota does that.
If you want to get into specifics for your line, click “Contact Mark” on the right sidebar —–>
That will email me.
Thank you Mark, I realized with your answer that what I optimized is the cycle time and not de takt time. Yes indeed the existing takt time cannot be achieved and the modification of the Cycle time is a step forward to match the customer needs.
the modification realized from the DMAIC project are indeed linked with space people, there is no so much money as a cost, I wanted to put calculate a payback, but I understand now by your answer that there is no sense to do that except to compare project between themselves (cost to cost).
Thank you very much
Mark,
Thanks marks for spending your valuable time to answer my question. I think that gives me a better picture of it. Can you explain me what do you mean by line stop buffers a bit clearly?
Dharmic –
Any production line is going to have occasional stoppages.
Putting a small fixed maximum quantity buffer between sections of the line will allow one section of the line to stop for a short period, and then restart, without affecting the sections adjacent to it for at least a few minutes.
The key here, though, is to limit the size of those buffers, otherwise you are right back into push production and hiding the problems, which defeats the whole purpose of a timed assembly line to begin with.
Hello Mark,
If I have 6 machines (punching presses) and have 4 workers, who effectively work 7.5 hs out of a 9 hour shift each:
How do I calculate my capacity?
Is it 7.5 X 4 or 6 X 7.5?
thank you
Adrian –
There isn’t enough information to answer your question.
Can the four operators keep all six presses running? How many presses are actually running for 7.5 hours?
Hello Mark,
I have come across problems with take time. I have a demand for 30 reports per week and have 25 analysts working. Total available time is 8 hrs (Assuming in ideal world). How do I calculate take time?
Also on average an analyst is spending 20 hours per report (Which is the process lead time I assume, correct me if I am wrong).
Your help will be appreciated.
Regards
Deepti Varshney
Deepti –
If you want to actually level out the flow with a takt time, then you would calculate how much time elapses between the time you must complete one report until you must complete the next one. Takt time is the cadence of things coming off the end of your line.
Every 40 hours you need to complete 30 reports.
That means you must complete one report every 80 minutes, day in, and day out. THAT would be your takt time.
However your process seems to be one analyst starting and finishing one report, without passing it to someone else.
If that is the case:
You have to produce 30 reports / week.
It takes 20 hours to produce a report.
That is 20×30= 600 hours producing reports.
There are 40 hours in a week (actually less, but you said 8 hours was available).
600 hours of work / 40 hours available = 15 people required.
You likely need more due to the variation.
Hello Mark,
I am building a capacity model in excel for my plant. The assembly process has ~40 steps. There are only 8 operators who handle 4-5 steps each (Steps handled can be at the start and end of the line, not sequential. Ex: Operator A handles step 1, step 2, then does step 32, 33). Takt time is 8 minutes. Cycle time is 300 minutes. 1 bottleneck operation step ( a baking process which is done with a batch of 20 units together) takes 180 minutes. Another bottleneck operation takes 20 minutes and there is no way to reduce that. Can you explain how to estimate the number of units that can be produced every day? Plant operations are 24*7.
Thanks.
Shalini –
How many units must you produce each day? That is where you begin. Then your process and resources either can, or cannot, meet that requirement. If they can’t you have to fix it.
You say you have a takt time of 8 minutes. That defines the number of units you are going to make.
1440 minutes / 8 minutes = 180 units.
You say your cycle time is 300 minutes, but you don’t say what you mean by “cycle time” here.
Is it lead time through the process?
Is it the total work required?
If your baking process takes 180 minutes, does that include the unload/load time for the oven, or just the baking time? How much time is the oven tied up for one batch of 20 units?
If you have another bottleneck operation that takes 20 minutes, how many pieces is it processing at once?
You need to think in terms of rate rather than units / day if you want to build a capacity model.
Hi Mark,
In a case of simulation of semi products (bulk), should I combine takt time of semi products with that of their corresponding finished goods for calculation?
Thanks for your comment.
Norman –
I am sorry, I am not sure what you mean by “semi products.”
In general, you are looking at the work which must be done.
How often must the people doing the work complete one unit of production? It is always from their perspective.
dear sir,
how to plan assembly line station as per takt time? (for new line setup)
Sohit –
Planning an assembly line is a bigger task than I can cover in a comment reply.
At a high level –
You need to calculate the takt time for the line, speed that up a little to determine a planned cycle time (the actual line pace).
Then you need to understand the *total* cycle time involved in building the product. How long would *one person* spend to build it from start to finish?
Divide that total cycle time by the planned cycle time, and you have a *starting point* for how many positions you need.
Next is determining the exact work for each position. The quick way for a first pass would be to simply start timing the build. As each interval of the planned cycle time elapses, you know you need to move to the next position. This does NOT give you any improvement, but gives you a starting point.
After that, it is a matter of continuous improvement, focused especially on making sure the work itself is smooth, unhurried, and addresses any safety concerns while assuring quality.
If you have specific questions, please click on Contact Mark on the right sidebar and write to me directly.
How can I calculate over time? What is Work Pace Method?
Good Information ,
It takes time for me assimilate concepts especially when I have to deal with single piece flow and batch production, math is math reality is little bit different.
Thanks
Dear Mr. Mark
Good Day
I’m doing Kaizen activities at my supplier end. My problem is with takt time calculation, the gear supplier is handling around 90 part no.’s and all account for production quantity of 40,000 on average. This gear supplier doesn’t have a typical line layout in which we can calculate takt time easily, but they have a process layout. Machines can be used for multi-variety of parts. Can you help me out any effective way to calculate takt time. ShouldI consider the whole quantity to be produced irrespective of the part no. in takt time calculation? ??
Ankur –
Obviously I would have to see the factory for myself to give you a really adequate recommendation.
Here are some suggestions.
Inside the factory, takt time represents the cadence of demand from the downstream consuming process.
See my post Takt Time is Local for an explanation.
In your supplier, however, it is likely that each job is routed from department to department without a real attempt to run at any kind of flow or cadence. You (as the customer) know the takt time the supplier needs to complete your various items, but likely that doesn’t translate to what their individual operations have to do.
Since their operations are putting many different products across their machines, what you can do is determine how often they need to run a batch of your items. For example, if they run 24 hours, and need to run 1000 of your items every day, and they run in batches of 100, then they need to run one of your batches every 144 minutes. (1440 minutes / 10). That would be a start to smoothing things out.
However it is equally likely they don’t run the shop floor that way. However, they can release the orders in a level manner (one every 144 minutes), and they can check if they are completing an order every 144 minutes, and that is a start.
Mark
Dear Mark,
Thank You so much for the suggestion. I have worked out with their Layout and made some Presentation related to their layout, Walking time, handling time and takt time. I will send you on email. Thank you.
hii
I have a problem regarding calulating the takt time, lead time and throughput please if it is possible can you help me.
Consider that you are a consultant responsible for improving operations at an airport. The airport has been experiencing chronic problems with long delays in the time it takes to check in and then travel to the gate. In addition the number of passengers processed per day, compared to management’s expectations, is very low. Based on the individual processes, cycle times, and metrics, analyze this process of getting passengers through the airport. Calculate (a) TAKT Time, (b) Leadtime, and (c) Throughput.
15 Passengers every hour
1. Passengers Arrive and Queue [ 5-7min ]
2. Patients check-in to obtain boarding pass [ 3-4min ]
3. Baggage check-in [ 7-15min ]
4. Passengers undergo security checks. [ 3-5min ]
5. Passengers walk to gate [ 5-10min ]
Dhruvil – This looks a lot like some kind of exam question rather than a project.
But everything seems to be simple addition and division.
(I am assuming 15 passengers / hour is ARRIVALS). The standard takt would be pretty simple: 60 minutes / 15 passengers = 1 passenger every 4 minutes. But passengers, like other asynchronous events, will ALWAYS arrive in batches.
As for everything else, it isn’t clear from context whether the times are the time it takes a passenger to go through the process, or the cycle times of the process itself. That makes a BIG difference.
If the times are the time it takes a single passenger to go through each step, then there isn’t enough information there for calculating throughput, since the actual rate of processing (passengers / unit of time OR unit of time / passenger) isn’t included in the information.
As for their lead time through the process – it’s pretty simple to just add up all of the queing and processing times. One passenger is going to spend between 5+3+7+3+10 = 28 minutes up to 7+4+15+5+10 = 41 minutes going through the process. (I am assuming these times include wait / queue times at each step. If they do not, there is not enough information to determine the lead time)
The other possibility is that some of those times are actually ranges of cycle times (or more specifically, exit cycles, which would be the RATE of output).
Arriving and queuing doesn’t sound like a process, so I’d assume that is waiting time. But who knows? Does a passenger arrive every 5-7 minutes? If so, that is slower than 15 / hour, so I’m not sure.
Assuming check-in / boarding pass is a CYCLE time, then that is more or less keeping up (except when passengers arrive all at once, then things will back up there.)
Baggage check-in at 7-10 minutes would be a problem if that is an exit cycle. Passengers are arriving every 4 minutes (on average), so they would need to HOPE for a lot of lulls when NO passengers arrived. But overall, things are going to back up there. If passengers arrive in a level manner, this process will, at best, send a passenger to the next process every 7 minutes.
Security checks – since a passenger can only ARRIVE every 7 minutes (or slower) from baggage check-in, security is never going to have much of a line.
Walk to gate is a transit time, not queuing or waiting. It is part of lead time, but not part of throughput.
So *IF* those times represent cycle times, and *IF* passengers arrive level and *IF* there is only a single queue for baggage handling and *IF* that time represents EXIT CYCLES for individual passengers, then baggage check-in is an obvious bottleneck.
BUT – if a consultant came to me with this cursory information and started to draw conclusions, I would fire him on the spot because he doesn’t know what he is doing.
– if I am a consultant at that airport, I am going first going to spend a few days observing, and perhaps even going through the process myself to learn more about the dynamics. I am going to have a stopwatch handy, and work to determine actual arrival patterns as well as the exit cycles for each of these processes.
At that point, based on lowest-repeatable-times, I should be able to develop a hypothesis about what the throughput SHOULD be. Then it’s back to observation to determine why it isn’t.
Bottom line: To answer this question, you’ll actually have to spend a lot of time at the airport. 🙂
By the way – if it only takes 5 minutes to get through security, kudos…. or I wouldn’t want to fly on a plane taking off from there. One or the other. 😉
I had a problem solving this was that they have given approx time like 5-7 , 5-10 min its too much confusing which to consider for lead time and i m not clear about the throughput thing now also.
But thank you so much for your effort for directing me how to tackle this type of problems.
Thank you.
Hi Mark,
Question… Which system is more efficient, a fixed rigid Takt based production line or a flexible One Piece Flow?
In terms of designing a manual based production line to meet a theoretical forecasted ‘takt time’, (10 fixed workstations needs 10 operators), how do you fluctuate in a seasonal business (+/-25%/month) to ensure you don’t end up over stocking your internal customer? Would One Piece Flow be more efficient on the whole value chain in this instance due to its flexibility?
Regards,
Darren
Darren –
Good question. I am working up a coherent reply, in the form of a new post.
Darren –
The short answer is that your takt based production system will be more inherently efficient *IF* the actual work cycles are balanced to the takt time.
Takt time reflects a rate of demand, not a rate of production. You want your capacity, and rate of production, to match the takt for greatest efficiency.
From the limited information, it looks like your 10 person line is capable of outproducing the downstream process. This means the 10 person line’s lowest repeatable time (i.e. the speed they are able to run) is faster than the takt time (the rate of demand for their output.)
At this point, we are (or more precisely, I am) out of information.
See the latest post (https://theleanthinker.com/2016/11/12/its-what-must-we-learn-not-what-should-we-do/) as well, for how to think through the problem. Or at least how to start. Feel free to contact me to discuss specifics.
Hi Mark,
I’ve learned so much by just reading your responses to these questions, so I thank you for taking the time to reply with meaningful and insightful answers. I’m a recent IE graduate and love the concepts of Lean simply for how many ways and areas of work (and personal life) that it can be applied in. In my opinion, since its philosophy centers around efficiency in processes, and processes are EVERYWHERE, you can improve processes ANYWHERE by using Lean concepts and tools. But I still have a long ways to go for a deep understanding and thereby having the skill to apply it in any situation. So I’d really appreciate your expertise and thoughts on my below work situation:
My company is implementing a new ERP system that will schedule production based on this (simplified) criteria; total cycle times per product, maximum available time, and production line constraints. Let me explain.
1. Total Cycle Time per Product: We are a make-to-order door assembly production system (that does not and will not forecast finished good quantities [I’ve tried to convince management this is important to no avail], but only forecasts the component usage [hinges, jambs, stops, door slabs, etc.]). So we gathered estimated cycle times for each individual operation. And so each product, dependent on the operations that are required, the ERP system will add up all the cycle times involved to compute a total cycle time for the product. An example being an interior door slab with a single bore will take less time to make than an exterior door with a deadbolt prep and a sidelight.
2. Max Available Time: no explanation needed, same as what you’ve been explaining in the above comments. With the exception that the ‘prepping’ processes tend to run a day ahead so all parts and pieces are ready when the door slabs enters one of the main assembly lines.
3. Production Line Constraints: Certain products (doors) can only be assembled on 1 prod. line, others can be assembled using 1 of 2 prod. lines. The criteria and constraints to decide this are all built into the ERP system so it knows which prod. lines a door can and cannot be assembled in.
So with these 3 in mind, the ERP system creates the production schedule based off required ship dates, and will tell you whether or not all orders can be produced in time for the ship date, or if it needs to have a later ship date. It works on a first-in-first-out basis where the only way it will allow you to OK the ship date before scheduling it is if there is room in the schedule to make it in time. The nice part of our manufacturing system is that the only batching in the system are the WIP points between processes, otherwise the processes are all 1-piece-flows. This production scheduling methodology also has the advantage of easily seeing the bottleneck department and bottleneck line. The product (depending on the operations needed and production line constraints) has to flow through certain departments and lines, and if the system is constantly trying to max capacity, you can consistently see which department and which line is always full therefore the bottleneck within the system.
FIRST QUESTION: Do you have any suggestions to help make this system run more efficiently? Or resources I can tap to help me understand how I could improve upon this?
SECOND QUESTION: Is takt time the best tool to use in my situation in order to help improve the processes by identifying the problems that are causing delays? If not, what would? My guess to the answer of this question is below;
Takt time does NOT apply. Takt Time=Available Time/Required Output…OK, so in my case that means Available Time/Output that the system schedules (Production Line Capacity). In more cases than one, we don’t have the capacity on our main assembly lines to meet the required ship dates therefore not meeting customer demand. Hence why calculating takt seems pointless to me. Takt only applies when we are running BELOW capacity therefore it would help us to not OVER produce in non-bottleneck departments and lines. So whether or not the department or line is a bottleneck, I think I would just set up time slots to periodically check if we’re producing the product at the rate we planned on. In other words, comparing ACTUAL cycle times (actual start times of products) vs. PLANNED cycle times (the times products were scheduled to start) is the metric I should really care about, NOT takt time. Thoughts? Am I right on or am I way off?
Thank you in advance!
Mike –
I’m going to give you a quick reply to your last question. At the same time, I am working up a follow-up post to the original (above) that goes into some more detail.
Takt time is an expression of your external demand (or the downstream demand on an internal process). It is designed to provide a point of comparison between the rate your customer requires and the rate you are actually running. Takt time is just a number with two inputs, and neither of those inputs has anything to do with how your factory is set up or operates.
You are quite correct that if your process is capable of producing faster than the takt, then doing so would be overproduction. Slowing down to the takt time changes overproduction into waiting, but at least now you can see the excess capacity.
But what if your bottleneck is slower than your takt time? You shouldn’t just ignore the fact that you have more demand than you can meet. Knowing the takt time is more important than ever here.
If you consistently produce slower than your takt time, then your backlog is going to get longer and longer. If this is not happening then it means there are times when your demand slows or your production increases enough to catch back up. Comparing your actual production to the takt time can help you see that as well.
If your bottleneck cannot meet takt time that means the bottleneck’s cycle time is slower than the takt time. That tells you, the industrial engineer, where you need to focus your attention to break the bottleneck. IDEALLY you want the bottleneck to be the customer, meaning “We can make a little more than we are selling.” That does two things.
First, it gives you a little headroom to deal with fluctuations and catch up from minor problems.
Second, it tells sales they can sell more – in essence it makes “sales” the bottleneck to more profit. You already have the capacity, so you get to keep 100% of the value-add on all of those additional doors. Overhead, capital, wages, etc. are already paid for.
Bottom line: Takt time gives you a point of comparison. It doesn’t stand alone, it is intended something to compare to your actual rate and cadence so you can see where you need to adjust or improve your process to better serve your customers.
Thanks for your interesting article, I am a big fan of the reality myself.
In my world, investment banking, Takt time is not much applicable (other than call center). We have literally 20 distinct investment products, rules are different based on client status (residency, type of job, …), all sales rep are doing A-z in one meeting with client, clients buy one or more products in one visit, account set up may take 20 min for clients with investment knowledge and could take over 60 min for clients with out investment knowledge, we can not buffer 🙂 product ahead of the time, we lunch at least couple of new offers every year which disrupt the demand vloume and many other factors ….
As a result, we do not have takt time 🙂 or let say, our demand is changing by hour every day. However, we know the pattern of demand for each product, like registered products are high between Jan – April, and we plan accordingly and deal with variation in an agile way.
Mark,
I am one the employees in a rather large assembly operation. One widget every 11 days. Each station has 2 days for their process. There is some overlap in each station as one or more workers will finish the station task and another is prepping/starting another widget piece in the station.
If at any point, a supplier is unable to feed us a part for a certain process station, they (management) shut down the whole line until that part arrives. Then we start again where we left off. Then we work overtime to “catch up”.
Is there room in this SixSigma thing for a BUFFER?
During the shutdowns, the workers are farmed out to all corners of the facility doing god knows what.
All the while, any station ahead of the delayed part are allowed to continue building until the widget is complete.
Now, 5 days later the part arrives and everyones process continues, except the folks that were left to continue their respective process are now idle until the other processes feed them product to continue.
Why can’t the earlier processes continue up to the “failure point” instead of just jamming the brakes on the whole shebang?
Since our process is so elongated, it makes sense to all us laymen to buffer (our words)
Shutting down makes sense when each station is 55 seconds. We get that.
Thank You for your time.
Fred
Fredrick –
From the top:
When you say one “widget” every 11 days, but each station has 2 hours for their process, it sounds like your line is 22 days *long* but you are trying to complete one unit every 2 hours. Is that correct? If so, then your takt time (or more specifically, your target or planned cycle time) is 2 hours.
As I understand your comment, this is what is happening:
You have a very long series of work stations, each with two hours of work to do.
The total time through the pipeline is ~ 11 days.
The idea is for the line to index every two hours.
If a station in the middle of the line encounters a part shortage the following occurs:
The stations DOWNSTREAM (closer to the customer end) of the line continue to work, which opens up a gap in the line.
The stations UPSTREAM (closer to the beginning of the line) of the line are idled until the part arrives.
When the part arrives, the UPSTREAM stations work overtime to catch up.
The DOWNSTREAM stations, since they continued their work and emptied out their part of the line, must wait until the line upstream of them fills again.
I have a couple of thoughts here.
1) Just to be clear, this isn’t anything close to what Toyota does. They would never open up a gap in the line – and you can readily see the reason. Eventually, everyone on the line is idled for the same amount of time. In your case, you are delaying idling the downstream people, but eventually they, too, will have nothing to do.
2) The entire point of line stop is to force attention onto the problem so there is pressure to fix it. If you have chronic part shortages that are shutting you down, then there should be a major effort to get to the bottom of the cause(s). See my post “a morning market“. That organization aggressively addressed their part shortages and, over about 8 months, fixed the problem.
3) Toyota has small buffers all over the plant. However, their intent is not to simply allow production to continue if there are problems are unresolved. Those buffers are there so they are *encouraged* to signal problems, knowing they don’t immediately idle everyone. However, if the problem is not resolved within a very few minutes, buffers fill (or empty) and successive sections of the line are halted. In your case, however if your delays are on the order of 5 days, which is half the length of your line, buffers would not help very much. The buffer would fill (or empty) pretty fast, and you would be in pretty much the same situation you are today.
In the end, I don’t have enough information to make a judgement about what your management intends to accomplish with their policies. But unless there is a concentrated effort to figure out why the line stops occur and address them, what you describe is *not* what we could call “lean.”
Mark,
Thank you for the quick reply.
Our cycle time for each station is 2 DAYS, not hours.
But, I do understand what you are saying about stopping the whole line so everyone is idle the same amount of time and to put pressure on the failure point.
Fredrick –
Oops – yes, I knew it was two days, but I mis-typed. It was a late night at the end of a long day. 🙂
The principles remain the same.
I’m happy to discuss all of this in any level of detail you like. If you click “Contact Mark” on the right sidebar, that will email me directly.
Mark
Hi, great post!
I’ve been studying these and other concepts and I’m specially confused about Takt Time.
From what I got from this post, Takt Time is like a goal, it is what you have to perform to met the customer need, but also to avoid over production.
The question I still have is theorical: can I say that my goal-Takt-Time is 10 minutes (customer need) and my current-Takt-Time (what I’m actually doing) is 20 minutes? Or there is another name/term for that?
Thank you.
Matheus –
The key point of the article is “Be clear what you are talking about, because a lot of people use the same words with different meanings in mind.”
Takt time is usually an expression of the customer need, regardless of your capability to meet that need.
It is also a deliberate choice of how fast we are going to try to run.
If you are making a deliberate choice to produce a unit every 20 minutes, and nobody is *currently* under pressure to try to run any faster, than your takt time is 20 minutes.
If you are making a deliberate choice to produce a unit every 10 minutes, but *can’t do it* then your takt time is 10 minutes, and you are not meeting that takt time.
That being said, it is always OK to say “We are running fast enough today, but by the end of the year, we need to be running twice as fast” – now we have a “Challenge” and need to start working on getting cycle times to the point where we can meet the new takt time.
In the end, though, I would be much less concerned about hair-splitting on what the words mean to outsiders, and making sure that everyone you are communicating with understands what you actually mean.
Hi mark,
i just wanna ask for help about finding a solution on how to standardize the process and eventually determine the downtime in the production of my company.
the case is that:
– the company is basically made to order. they determine the product to produce by forecasting the need of our present clients (or sometimes it is given to them by the client)
– theres no similar process because it depends upon the specs of the client, and tonnage of the product.
– the process cant be shorthen or i cant make the different tonnage of products with same process into one or combine them because the quality will suffer.
– it’ll be really really hard because the process of clients are over 3000 (total number of process from different products atm). and im the only one who’s doing the task.
so how can i standardize this process?
Kin –
I would need to better understand your situation and the problem you are actually trying to solve before I could give you a meaningful reply.
If you want, feel free to write to me directly through the “Contact Mark” link on the right sidebar.
Hi, i am facing problem in calculating overall Process Cycle Time ie., start to end, because i have a 4 stage manufacturing line with following stage wise cycle timings.
Stage 1: Person is assembling and takes 5Min
Stage 2: The job is kept in Oven for 100Min
Stage 3: Person is wiring it and takes 6Min
Stage 4: Person is packing it and takes 7Min
So, should i consider the overall Process Cycle time as 5+100+6+7 Min OR since man is not doing any work when the job is curing in the oven will the cycle time be Just 5+6+7.
please clarify.
Your “start to end” time is simply the time it takes one item to flow through your entire process, including all queuing and waiting times. Since you only included the value adding operations, and I imagine there are queues and waiting, I cannot determine the total start to end time from the information you provided. The easiest way to determine this is simply to tag one item at the start of the process and time how long it takes to get to the end.
The operator cycle time (for determining how many people are required to do the work) would be the sum of the manual work:
Assembly: 5 min
Wiring: 6 min
Packing: 7 min
Total: 18 minutes.
It would also include whatever time is spent loading and unloading the oven *per piece*.
Thanks Mark
I am calculating productivity of person as “Qty Produced per person per Hour” , so , shall i include 100Min oven time also in that.
Hermanth – Unless someone has to stand there during that 100 minute oven time, there are no people involved in the 100 minutes, so no, that time does not count for productivity. [Output / Person / Period of time] is the simplest way to do that.
Thanks Dear Mark Rosenthal,
Kindly also clarify following for me.
Stage 1: Person is assembling and takes 5Min
Stage 2: The job is kept in Oven for 100Min
Stage 3: Person is wiring it and takes 6Min
Stage 4: Person is packing it and takes 7Min
When i stood at the end of Manufacturing line and measured the time between 2nd piece & 3rd piece OR time between any 2 successive pieces after the first one ,i found that after every 100 Min one piece is coming out. Is the PROCESS CYCLE TIME 100 Min?
What is the MLT in this case?
Labor utilization %?
Total Waiting time ?
I would be thankful if you can clarify above for me.
As I point out in the original article, there are a lot of different definitions for “cycle time.”
Your exit cycles are what you measure between individual units of output at the end of the line. If you are measuring 100 minutes, I would imagine that you only have one in the oven at a time, and the oven is pacing your line.
Your operator cycle time would be the 5 minute + 6 minutes + 7 minutes = 18 minutes.
If you are only processing one unit every 100 minutes, you need much less than one person to do this job.
Your labor utilization / waiting time (one is the inverse of the other) would depend on whether this person had other things to do.
Hello,
I have to establish thr no of work cell and the number of operators for a new project. Can you please help.
The calculated takt time for one product type is 48sec/pcs and for the other one is 32sec/pcs. We have available 2 shifts/ 7.71h/ shift with a 95% efficiency
The problem is we have an equipment which can deliver 5pieces every 25sec, while the mechanical assembly before the machine is 60sec/piece and the final assembly and packaging after the machine is 30sec/ piece. Anual volume is 257kpcs from 1 product and 418kpcs fron the 2nd product.
We need to decide how to run on the line to get the maximum output.
Thanks in advance,
Gabriela –
Your takt times indicate that you only *need* three or four pieces (total) per minute. Is that true?
What would be the combined takt time of both products together (just to confirm)?
Is this mechanical equipment dedicated to these products? Or is it shared with other lines?
If you want, you can email me direct by clicking “Contact Mark” on the right sidebar —–>
Mark
Hi there,
I am having a tough time calculating Takt, it feels like it should be so simple but something doesn’t seem right.
Here in our firm, we work in Batches (which vary from 12 to 16 depending on the cell), and we have 16 cells that the part moves through.
The Problem, is that each cell has a different number of shifts: 12 of them are 1 shift, 1 is 2 shifts and 3 are 3 shifts.
The Batches also pass back through previous cells a couple of times… (for example: laminating –> Autoclave –> Demoulding –> Laminating –> Autoclave –> Demoulding) so I was trying to Count them as “seperate” cells.
In that case we now have: 17 cells of 1 shift, 1 cell of 2 shifts, and 4 cells of 3 shifts.
Each shift is 8 hours with 45 minutes breaks and lunch.
Customer demand is 12 parts per day. We work monday to friday.
At first I had calculated Takt by calculating the average number of shifts: [(17*1)+(1*2)+(4*3)] / [17+1+4] = 31/22 = 1,40
So I had an average of 1,40 shifts per day.
In available hours that would be 1,40 * (8-0,75) = 10,15 h per day
Next, I divided available time by customer demand : 10,15 / 12 = 0,85 hours per part = 51 minutes per part.
Up until now, it all seemed alright to me.. Until I made a Chart showing the times for each process and which ones were above takt time. There was a process where the parts go into an Autoclave in a Batch of 12 to be processed for 7 hours (420 minutes), which is 8 times more than Takt time! And also 2 laminating steps that were nearly 3 times longer than takt! But we also had some process times that were only 1 Minute.
After a quick glance at the Chart, you can quickly guess that the takt time must be incorrect.
Do you have any suggestions?
I appreciate you taking the time to read this.
Best regards,
Zak
Zak –
The key here is that takt time is local.
Plus, it doesn’t matter if items are looping back around, they are still items which must be processed.
So – for each cell separately, what rate of production must they maintain to keep up with *their* demand? That is the question you are trying to answer.
Second – the actual processing times don’t matter. Takt time is a measure of demand, not a measure of capacity.
Third – when you say “batches” – are the items processed one-by-one within a lot, or are they processed all at once in a true batch?
If one-by-one, then batch size doesn’t matter. How many individual items must be completed during the day?
If they are a true batch, then use a “batch” as a unit of work for determining your takt time. How many batches *must* be processed?
Then work to reduce your batch size.
And work to eliminate the loop-backs.
And work to balance the work across the entire system so everything flows.
Great post. I never knew there were so many definitions of cycle time. I love how you clarified takt time for people in terms of reality. A simple explanation of what confuses many. Thanks.
I would like to know how to calculate fakt time in case multiple products are produced on same production machines
Abhijeet –
Takt time is independent of the machine or process. It is simply a calculation of the demand for the product which, in turn, gives you a starting point for the amount of capacity you need. Unit of Time per Unit of Output; whatever that unit of output is. That being said, you are factoring in things like changeovers and products with varying cycle times and trying to produce a schedule, it can get a little more complicated – more than I can get into in a blog comment.
If you have a specific scenario, feel free to email me (see the “Contact Mark” link on the right sidebar) and I might be able to guide you in the right direction.
hi mark , i have a issue. my company running plastic injection molding parts. currently my manager ask me to take cycle time. problem we have more than 500 product and daily different parts. for this can use median for calculate cycle time ? example break parts for 3 section . big /small/medium big and compare this parts cycle time and make standard cycle time for these product ? i mean average cycle time for 500 parts . i need to find productivity so i need cycle time for calculate . please help me . Thanks
Kanesh –
It is hard to give you a specific reply without a lot more information about your process, so some of this is going to be general guidelines.
So my first response is to ask “How are you defining productivity?” and what kind of productivity are you trying to measure? I ask that because all of the injection molding machines I have seen are automated and run on a pretty regular cadence once they are up and running after a changeover. The question here would be “Is the machine cycling at the rate it is supposed to?” for example.
When you are running a lot of changeovers, with items that have a lot of variation in their demand as well as their cycles, there is probably more to that than I could answer in a blog comment.
My first suggestion here would be to just watch the operation and look for events that disrupt the smooth flow of work. That would probably tell you where to start digging deeper. If you want to discuss more, hit the “Contact Mark” link on the sidebar, send me an email, and we can dig into some more detail on your situation.
Use technology to automate and streamline processes.
This can free up staff to focus on more complex tasks and help to ensure that processes are followed even when there is high turnover.
Cross-train staff. This will help to ensure that there is always someone who is
familiar with a particular process, even if the person who is normally responsible
for it is unavailable.
Create a culture of continuous improvement.
Encourage staff to identify and report on areas where
processes can be improved. This will help to ensure that
your internal control system is constantly evolving
and adapting to the changing needs of the organization.
Are you stilll answering the comments in this blog post and helping people? if so, I want to consult with a specific case.
Sure – if you have a question, happy to try to answer.
Thank you, here’s my case scenario, I’m in a service based industry, we issue permits ruled by a national law here in my country. Well I want to calculate takt time and determine the rythm of production, bottle necks, and quantity of employees required per step. Well taking one of the type of permits we issue to make an example here, the law says we need to issue it in 30 days, this is after the user submit the request in the platform, we should finish the whole process in 30 days. This is no being fulfilled. Welp I want to know if is still ok to aproach this dividing the deman in a month by the available time to do the job in the month. Or we can approach in a different way here. Since this number would be so unreal. Given that the task require a specific amount of time to get delivered.
Keidy –
Takt time the rate of demand, and is not related to how long it takes to produce a single item.
Let’s put this in the context of an assembly line first, then relate it back to what you are trying to do.
A typical automobile assembly line has a takt time of 60 seconds (just to simplify for the discussion).
But it takes about six hours, or 360 minutes, to actually assemble the car.
In this simple case, we can determine that we need 360 assembly positions in the line, each completing its task on one car every minute.
We can use any amount of time in the numerator of the takt time calculation, as long as the demand number in the denominator reflects the demand during that time period. For processes like yours sometimes that is easier than minutes in a day.
Let’s take a week – just as an example – as I don’t know your specific case.
Question one: How many permit applications do you receive in a week?
Regardless of whether it takes an hour, or takes a month, to process one, you need to COMPLETE the same number of permit applications each week in order to keep up with the demand.
In other words, the number of permits you are processing at any given time is a constant (or close to a constant) number: the number you complete = the number of new ones you receive. If that number remains more or less constant, then your process is keeping up with demand.
That is the first thing to consider: How many do you need to complete each week to keep up with demand?
Then divide the amount of time in a week by that number, and you have the takt time.
If you have 35 productive hours in a week (which is pretty typical here, I don’t know your case), and you have to complete 70 permits in a week to keep up with demand, then you should look to COMPLETE a permit every 30 minutes.
That would be your takt time.
From there, the next question is “How much time does it actually take to process a permit?” And by this I mean the time actually working on it, NOT the time the applications are waiting in queues. Let’s call that the cycle time. You can only determine it by measuring the actual work time. Assume this is the time for a problem-free, typical, application.
If you divide the total cycle time: The time it takes to do the work by the takt time you get the number of permits you must have in work at any given time.
So… if it takes 10 hours of work to actually complete a permit, and you have to complete a permit every 30 minutes, you will need to have a minimum of 20 people actually working on permits to keep up with this.
Hope this helps.
Feel free to respond with more specifics if that would help.
This was clear, thanks a lot Mark.
Glad to help.
If you want to discuss more, feel free to respond here or directly via “Contact Mark” in the right sidebar.
Hi-I love reading the new comments on a post from years ago. And now I have my own question about demand. I work in the insurance industry with people who make claim decisions. Throughout the day the employee gets electronic tasks added to their individual worklist. The tasks vary in what actions are needed, when they are actually due and how long they take to complete. How can I best think about the demand? Is it by total tasks that occur in a day, or should they be segmented by some logical categories? Thank you
Ted –
At first glance your case looks like an opportunity for segmentation / stratification of the work, but that is just first glance. There are a number of ways to go about it and they would depend on specifics.
I had a similar case years ago. When we looked at the actual tasks being assigned, it turned out that about 80% of them were routine and took about an hour to process. It was the other 20% or so that were driving the variation. (Vilfredo Pareto strikes again.) One person was able to handle the workload of the routine tasks, so long as they were classified correctly and ready to go when they went into his work queue. That was the first step, and removed the processing bottleneck.
In your case the first step would be to “grasp the current condition” and dig in to find what is stable, what is true variation, etc. all with the objective of creating stability in the workflow.
I know this is vague, and a bit off-topic, but it is where I would start. If you want to discuss directly, you can email from “Contact Mark” on the right sidebar.