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.
Comments 101
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…
Posted 29 Apr 2010 at 12:33 am ¶hi, Using takt time the number of resources can be calculated. but how to optimize them in case of limited number of available resources.
Posted 29 Jul 2011 at 4:50 am ¶Jyoti -
Posted 29 Jul 2011 at 11:05 am ¶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 …
Posted 24 Aug 2011 at 8:13 am ¶“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).
Posted 24 Aug 2011 at 5:08 pm ¶Hello,
Posted 03 Sep 2011 at 1:28 pm ¶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
Posted 03 Sep 2011 at 1:49 pm ¶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 :
Posted 13 Oct 2011 at 12:06 am ¶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.
Posted 13 Oct 2011 at 12:54 am ¶hi,should the OEE be taken into account while calculating takt time???
Posted 17 Oct 2011 at 5:54 am ¶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.
Posted 17 Oct 2011 at 11:43 am ¶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.
Posted 25 Oct 2011 at 9:56 am ¶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.
Posted 25 Oct 2011 at 8:45 pm ¶The number of people required is calculated by total cycle time / takt time.
Hi Mark, thanks for ur reply on my query..
Posted 30 Oct 2011 at 5:29 am ¶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.
Posted 30 Oct 2011 at 7:23 pm ¶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
Posted 15 Nov 2011 at 2:13 am ¶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.
Posted 15 Nov 2011 at 11:42 am ¶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?
Posted 16 Nov 2011 at 1:17 am ¶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
Posted 16 Nov 2011 at 5:54 am ¶Thank You Mark Great Information.
Posted 18 Nov 2011 at 10:46 am ¶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!!!!
Posted 07 Dec 2011 at 10:33 am ¶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.
Posted 07 Dec 2011 at 7:33 pm ¶Your knowledge astounds me! Thnx again Mark
Posted 08 Dec 2011 at 7:49 am ¶its very interesting, concepts.
many thanks,
Posted 06 Mar 2012 at 11:17 pm ¶What do you find interesting?
Posted 07 Mar 2012 at 11:12 am ¶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
Posted 09 Mar 2012 at 4:09 am ¶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.
Posted 09 Mar 2012 at 4:13 am ¶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.
Posted 10 Mar 2012 at 9:27 pm ¶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
Posted 11 Mar 2012 at 8:24 am ¶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.
Posted 11 Mar 2012 at 10:23 am ¶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.
Posted 11 Mar 2012 at 5:16 pm ¶nice article, easy to understand
Posted 13 Mar 2012 at 9:44 pm ¶can we use value stream for one part processing instead of for the whole factory where multiple products are produced?
Posted 13 Mar 2012 at 9:45 pm ¶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.”
Posted 13 Mar 2012 at 10:01 pm ¶Hi!
Posted 19 Mar 2012 at 7:26 am ¶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.
Posted 19 Mar 2012 at 5:24 pm ¶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
Posted 21 Mar 2012 at 11:08 am ¶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.
Posted 21 Mar 2012 at 3:36 pm ¶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
Posted 05 Apr 2012 at 10:58 am ¶Start out with a basic block diagram that shows how each process flows into its customers.
Posted 07 Apr 2012 at 10:08 pm ¶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
Posted 09 Apr 2012 at 1:18 pm ¶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
Posted 11 Apr 2012 at 10:00 am ¶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.
Posted 11 Apr 2012 at 6:40 pm ¶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
Posted 19 Apr 2012 at 2:09 am ¶My thoughts are “What obstacles are in the way of running to a level production schedule every day?”
Posted 19 Apr 2012 at 11:55 am ¶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
Posted 23 Apr 2012 at 12:18 am ¶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?”
Posted 23 Apr 2012 at 2:58 am ¶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?
Posted 02 May 2012 at 9:49 am ¶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!
Posted 02 May 2012 at 9:53 am ¶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.
Posted 02 May 2012 at 6:56 pm ¶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
Posted 09 May 2012 at 2:54 am ¶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.
Posted 09 May 2012 at 9:26 am ¶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.
Posted 12 Jun 2012 at 9:15 am ¶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.
Posted 13 Jun 2012 at 12:41 pm ¶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?
Posted 14 Aug 2012 at 1:40 pm ¶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.
Posted 15 Aug 2012 at 9:52 pm ¶Great article
Posted 18 Aug 2012 at 10:49 am ¶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.
Posted 29 Aug 2012 at 11:44 am ¶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.
Posted 30 Aug 2012 at 3:50 am ¶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,
Posted 30 Aug 2012 at 7:34 am ¶Ibrahim
Are these machine cycles, worker cycles?
Posted 30 Aug 2012 at 2:34 pm ¶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,
Posted 30 Aug 2012 at 4:45 pm ¶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 ——>
Posted 30 Aug 2012 at 10:50 pm ¶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,
Posted 31 Aug 2012 at 5:27 am ¶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.
Posted 31 Aug 2012 at 12:08 pm ¶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,
Posted 31 Aug 2012 at 2:50 pm ¶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?
Posted 17 Sep 2012 at 2:53 am ¶Cheers / Matt.
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.
Posted 20 Sep 2012 at 4:37 am ¶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?
Posted 20 Sep 2012 at 6:13 pm ¶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.
Posted 21 Sep 2012 at 8:35 am ¶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.
Posted 22 Sep 2012 at 8:49 pm ¶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.
Posted 22 Sep 2012 at 11:32 pm ¶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?
Posted 16 Oct 2012 at 6:03 pm ¶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.
Posted 20 Oct 2012 at 9:59 pm ¶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.
Posted 20 Oct 2012 at 10:08 pm ¶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
Posted 03 Dec 2012 at 2:38 pm ¶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.
Posted 03 Dec 2012 at 9:52 pm ¶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?
Posted 13 Dec 2012 at 2:17 pm ¶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.
Posted 21 Dec 2012 at 6:50 am ¶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
Posted 22 Jan 2013 at 4:05 am ¶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.
Posted 22 Jan 2013 at 7:55 am ¶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.
Posted 22 Jan 2013 at 6:46 pm ¶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.
Posted 22 Jan 2013 at 7:11 pm ¶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
Posted 24 Jan 2013 at 1:53 pm ¶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)
Posted 31 Jan 2013 at 4:52 am ¶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.
Posted 31 Jan 2013 at 6:03 am ¶Hi Mark,
Posted 03 Feb 2013 at 8:07 am ¶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.
Posted 03 Feb 2013 at 12:20 pm ¶pls give more examples for takt time
Posted 13 Feb 2013 at 10:12 pm ¶My cycle time is 155 sec…and my part transfer time is 32 sec. I need to calculate the production rate…
Posted 01 Mar 2013 at 8:47 am ¶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.
Posted 02 Mar 2013 at 11:01 am ¶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)
Posted 11 Mar 2013 at 1:15 pm ¶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?
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.
Posted 12 Mar 2013 at 7:15 pm ¶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.
Posted 14 Mar 2013 at 11:30 am ¶Vinay -
Posted 14 Mar 2013 at 11:30 am ¶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.
Posted 25 Mar 2013 at 11:56 am ¶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:
Posted 25 Mar 2013 at 5:44 pm ¶- Know how long you have.
- Verify the actual time against the prediction.
- Respond quickly to anything that is abnormal.
Hi
Posted 02 May 2013 at 3:46 pm ¶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.
Posted 02 May 2013 at 5:31 pm ¶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. ]
Posted 10 May 2013 at 5:52 pm ¶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.
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