Using Takt Time to Compute Labor Cost

How can I use takt time in computing labor cost?

Sometimes the searches that lead here give us interesting questions.

While simple on the surface, this question takes us in all kinds of interesting directions.

Actually the simplest answer is this: You can’t. Not from takt time alone.

Takt Time

Takt time is an expression of your customer’s requirement, leveled over the time you are producing the product or service. It says nothing about your ability to meet that requirement, nor does it say anything about the people, space or equipment required to do it.

Cycle Time

Cycle time comes in many flavors, but ultimately it tells you how much time – people time, equipment time, transportation time – is required for one unit of production.

Takt time and cycle time together can help you determine the required capacity to meet the customer’s demand, however they don’t give you the entire story.

In the simplest scenario, we have a leveled production line with nothing but manual operations (or the machine operations are trivially short compared to the takt time).

If I were to measure the time required for each person on the line to perform their work on one unit of the product or service and add them up, then I have the total work required. This should be close to the time it would take one person to do the job from beginning to end.

Let’s say it takes 360 minutes of work to assemble the product.

If the takt time says I need a unit of output every 36 minutes, then I can do some simple math.

How long do I have to complete the next unit?  36 minutes. (the takt time)

How long does it take to complete one full unit?  360 minutes (the total manual cycle time)

(How long does it take) / (How long do I have) = how many people you need

360 minutes of total cycle time / 36 minutes takt time = 10 people.

But this isn’t your labor cost because that assumes the work can be perfectly balanced, and everything goes perfectly smoothly. Show me a factory like that… anywhere. They don’t exist.

So you need a bit more.

Planned Cycle Time (a.k.a. Operational Takt Time and “Actual Takt”)

How much more? That requires really understanding the sources of variation in your process. The more variation there is, the more extra people (and other stuff) you will need to absorb it.

If we don’t know, we can start (for experimental purposes) by planning to run the line about 15% faster than the takt time. Now we get a new calculation.

85% of the takt time = 0.85 x 36 minutes = ~31 minutes.  (I am rounding)

Now we re-calculate the people required with the new number:

360 minutes required / 31 minutes available = 11.6 people which rounds to 12 people.

Those two extra people are the cost of uncontrolled variation. You need them to ensure you actually complete the required number of units every day.

“But that cost is too high.”

Getting to Cost

12 people is the result of math, simple division that any 3rd grader can do. If you don’t like the answer, there are two possible solutions.

  1. Decide that 360 / 30 = something other than 11.6 (12). (or don’t do the math at all and just “decide” how many people are “appropriate” – perhaps based on some kind of load factor. This, in fact, is a pretty common approach. Unfortunately, it doesn’t work very well for some reason.
  2. Work to improve your process and reduce the cycle time or the variation.

Some people suggest slowing down the process, but this doesn’t change your labor cost per unit. It only alters your output. It still requires 360 minutes of work to do one unit of assembly (plus the variation). Actually, unless you slow down by an increment of the cycle time, it will increase your labor cost per unit because you have to round up to get the people you actually need, and/or work overtime to make up the production shortfall that the variation is causing.

So, realistically, we have to look at option #2 above.

This becomes a challenge – a reason to work on improving the process.

Really Getting to Cost

Challenge: We need to get this output with 10 people.

Now we have something we can work with. We can do some more simple math and determine a couple of levers we can pull.

We can reverse the equation and solve for the target cycle time:

10 people x 30 minute planned cycle time-per-unit = 300 minutes total cycle time.

Thus, if we can get the total cycle time down to 300 minutes from 360, then the math suggests we can do this with 10 people:

300 minutes required / 30 minutes planned cycle time = 10 people.

But maybe we can work on the variation as well. Remember, we added a 15% pad by reducing the customer takt time of 36 minutes to a planned cycle time (or operational takt time, same thing, different words) of 30 minutes. Question: What sources of instability can we reduce so we can use a planned cycle time of 33 minutes rather than 30?

Then (after we reduce the variation) we can slow down the process a bit, and we could get by with a smaller reduction in the total cycle time:

330 minutes required / 33 minutes planned cycle time = 10 people.

(See how this is different than just slowing it down? If you don’t do anything about the variation first, all you are doing is kicking in overtime or shorting production.)

So which way to go?

We don’t know.

First we need to really study the current process and understand why it takes 360 minutes, and where the variation is coming from. Likely some other alternatives will show themselves when we do that.

Then we can take that information, and establish an initial target condition, and get to work.

Summarizing:

  • You can’t use takt time alone to determine your labor cost. Your labor cost per unit is driven by the total manual cycle time and the process variation.
  • With that information, you can determine the total labor you need on the line with the takt time.
  • None of this should be considered an unalterable given. Rather, it should be a starting point for meeting the challenge.

And finally, if you just use this to reduce your total headcount in your operation, you will, at best, only see a fraction of the “savings” show up on your bottom line. You need to take a holistic approach and use these tools to grow your business rather than cut your costs. That is, in reality, the only way they actually reach anywhere near their potential.

 

 

 

Another Homework Question

Another interesting homework question has shown up in the search terms. Let’s break it down:

23. if the slowest effective machine cycle time in a cell is 55 seconds and the total work content is 180 seconds, how many operator(s) should operate the cell so that labor utilization is at 100%?

I find this interesting on a couple of levels.

At a social level, the idea of cutting and pasting a homework question into Google hoping to find the answer is… interesting. Where is the thinking?

What are we teaching?

The question is asking “How many people do we need to run as fast as we can?” (as fast as the slowest machine). But how fast do they need to run? Maybe they only need a part every 95 seconds. If that is true, then I need fewer people, but I am going to run the slowest machine even slower.

In other words, “What is the takt time?” What does the customer need? How often must we provide it?

Then there is the “labor utilization” metric, with a target of 100%. Assuming the planned cycle time is actually 55 seconds (which it shouldn’t be!), we need 3.3 people in this work cell. (180 seconds of labor cycle time / 55 seconds planned cycle time: “How long does it take?” / “How long do you have?” = Minimum Required Capacity)

How about improvement? What do we need to do to get from 3.3 people to 3 people? We can solve for the labor cycle time.  55 seconds of planned cycle time * 3(people) = 165 seconds of total labor. So we need to get that 180 seconds down to a little less than 165 seconds.

Now we have a challenge. We need to save a bit over 15 seconds of cycle time. That might seem daunting. But we don’t have enough information (the current condition) to know where to begin. Then we can establish the next target condition and get started making things better.

These types of questions bother me because they imply all of these things are fixed, and they imply we run “as fast as we can” rather than “as fast as we must.”

Edit: Today I saw two more searches for:

total work content divided by slowest machine cycle time

so it looks like at least two others are working on the same assignment.  🙂

Thoughts?

Applying 5S to Processes

The idea that “you always start with 5S”, for better or worse, has been deeply ingrained in the “lean culture” since the late 1980’s. A lot of companies start their improvement efforts by launching a big 5S campaign.

Often, however, these 5S efforts are focused on striving for an audit score rather than focusing on a tangible operational objective.

It is, though, very possible to help bridge the gap by putting the process improvement in 5S terms. By using a language the team already understands, and building an analogy, I have taken a few teams through a level of insight.

For example –

We are trying to develop a consistent and stable work process.

Sort

Rather than introduce something totally new, we looked at the process steps and identified those that were truly necessary to advance the work – the necessary. The team then worked to avoid doing as many of the unnecessary steps as possible. In their version of 5S, this mapped well to “Sort.”

Now we know the necessary content of the work that must be done.

Set in Order

Once they knew what steps they needed to perform, it was then a matter of working out the best sequence to perform them. “Set in order.”

Now we’ve got a standard work sequence.

Sweep or Shine

The next S is typically translated as something like “Sweep” or “Shine” and interpreted as having a process to continuously check, and restore the intended 5S condition.

Here is where a lot of pure 5S efforts stall, and become “shop cleanup” times at the end of the shift, for example. And it is where supervisors become frustrated that team members “don’t clean up after themselves or “won’t work to the standard.”

In the case of process, this means having enough visual controls in place to guide the work content and sequence, and ideally you can tell if the actual work matches the intended work. A deviation from the intended process is the same as something being “out of place.” Then, analogous to cleaning up the mess, you restore the intended pattern of work.

One powerful indicator is how long the task takes. Knowing the planned cycle time, and pacing the job somehow tells you very quickly if the work isn’t proceeding according to plan. This is one of the reasons a moving assembly line is so effective at spotting problems.

Now we have work content, sequence and maybe timing, or at the very least a way to check if the work is progressing as intended. Plan, Do and Check.

I believe it is difficult or impossible to get past this point unless your cleanup or correction activities become diagnostic.

Standardize

The 4th S is typically “Standardize”

Interesting that it comes fourth. After all, haven’t we already defined a standard?

Kind of. But a “standard” in our world is different. It isn’t a static definition that you audit to. Rather, it is what you are striving to achieve.

Now, rather than simply correcting the situation, you are getting to the root cause of WHY the mess, or the process deviation happened.

In pure 5S terms, you start asking “How did this unintended stuff show up here?”

The most extreme example I can recall was during a visit to an aerospace machine shop in Korea many, many years ago. The floors were spotless. As we were walking with the plant manager, he suddenly took several strides ahead of us, bent down, and picked up….. a chip.

One tiny chip of aluminum.

He started looking around to try to see if he could tell how it got there.

They didn’t do daily cleanup, because every time a chip landed on the floor, they sought to understand what about their chip containment had failed.

Think about that 15 or 20 minutes a day, adding up to over an hour per week, per employee, doing routine cleanup.

If you see a departure from the intended work sequence, you want to understand why it happened. What compelled the team member to do something else?

Likely there was something about what had to be done that was not completely understood. Or, in the case of many companies, the supervisor, for his own reasons, directed some other work content or sequence.

That is actually OK when the circumstances demand it, but the moment the specified process is overridden, the person who did the override now OWNS getting the normal pattern restored. What doesn’t work is making an ad-hoc decision, and not acknowledging that this was an exception.

Once you are actively seeking to understand the reasons behind departure from your specification, and actively dealing with the causes of those departures, then, and only then, are you standardizing. Until that point, you are making lists of what you would like people to do.

This is the “Act” in Plan-Do-Check-Act.

Self Discipline or Sustaining

One thing I find interesting is that early stuff out of Toyota talks about four S. They didn’t explicitly call out discipline or sustaining. If you think about it, there isn’t any need if you are actively seeking to understand, and addressing, causes in the previous step.

The discipline, then, isn’t about the worker’s discipline. It is about management and leadership discipline to stick with their own standards, and use them as a baseline for their own self-development and learning more about how things really work where the work is done.

That is when the big mirror drops out of the ceiling to let them know who is responsible for how the shop actually runs.

Boeing Moving Line

Boeing’s “PTQ” (Put Together Quickly) videos show a time lapse of an airliner in production. They have been producing the for years – certainly since I was working there.

This one, though, shows something a little special.

When I first started working there, the idea of a line stop was unthinkable. The plane moved on time, period. Any unfinished work “traveled” with the plane, along with the associated out-of-sequence tasks and rework involved.

The fact that the 737 is now built on a continuously moving assembly line in Renton is fairly well known.

But what struck me in this PTQ video is that one of the things highlighted in it is a line stop. It happens pretty quickly at about 1:57.

The video is also full of rich visual controls to allow the team to compare the actual flow vs. the intended flow. See many many you can spot.

Taktzeit

Now and again someone wonders out loud why, in this lexicon of Japanese terms, we have the word “takt.”

I had always passed along what I had heard – that the word was German, short for taktzeit and used in their factories to represent the pace of production. During WWII, the Germans had helped the Japanese set up more efficient production lines, and the word migrated into Japanese usage.

All of this had been anecdotal.

factory_floor07But today I ran across Alan Hamby’s phenomenally in-depth reference site on the German WWII Tiger Tank. Alan has extensive detail on the Henschel Tiger Tank Factory, and in some of the photos are signs indicating the number of the “takt” or production position.

But don’t stop here. Take a look at Alan’s site, and look at how this factory is set up and operated. This plant was set up to produce a Tiger I tank every six hours, and built a total of 1375 of them between 1942 and early 1945. Yes, there is a lot of waste, but bluntly, I have seen 21st century factories making products of similar size and complexity that are far worse than this.

The idea of pacing and balancing production is not new. By the time these photos were taken around 1943, the concept had been proven for over 20 years. Yet when I visit factories today this is a seemingly novel concept. I always wonder why today’s operations managers are not insisting on at least the efficiencies that were achieved by 1935.

Thanks to Alan for his kind permission to bootstrap from his research and use these rare photos here.

Just to be clear, though, having a pace for production does not make a line “lean.” Far from it. But it is a foundational element. It may not be sufficient, but it is (in nearly all cases) necessary. What makes it foundational element for improvement, however, is not so much the pacing and balancing aspect. Rather, the concept of takt time can be used as a way to structure improvement goals and targets in a way that is meaningful to the people doing the work.

We talk a lot (all to much, in my view) about metrics, but tend to think of the things management is interested in – like labor productivity. But the way you get labor productivity is to focus on the takt time, the total cycle time, and the stability of that cycle time. Those are the things that determine how much gets done by how many people. You can measure “labor productivity” all you want, but you can’t change it unless you get down another couple of levels. Fortunately (for us) Reichsminister Speer didn’t figure that out.

 

By the way, just to put things into perspective:

In 1943, Boeing Plant 2 was producing one B-17 bomber an hour, sixteen planes a day, six days a week. They did it by using a paced assembly line and continuously working to simply and improve the flow.

One-off and Customization

One of the questions that comes up frequently in “lean” discussions is the issue of non-repetitive work. This is especially an issue with complex information processes such as bid proposals, estimates, etc.

While it is true that breaking down and understanding truly repetitive work is easier, the same principles apply to more complex tasks.

But first, I’d like to challenge some thinking. If you were to tell me that “every time we do this it is totally custom,” my question would be “If it has never been done before, why can’t everyone do it just as well as you?” What makes up your expertise? Why do your customers come to you?

I’ll answer: Because you know how to do it. Obvious, right? But that’s the point. You have experience, because you have done it before. You have a process of some kind. And you carry out that process to produce your customized product.

Further, you have some kind of idea of what a “defect free product” is. You understand what you want to accomplish.

Complex operations are built up from simple ones. The tasks that are done over and over are these simple operations. These simple operations are great sources of waste because (typically) no one ever examines them.

The idea that “lean” only works for repetitive processes is largely the fault of the “lean industry.” It focuses so much on takt time and removing waste that it has not, so far, gotten to the actual heart of what makes continuous improvement work.

In an ideal repetitive process running to takt time, there are a number of key ingredients.

  • There is a highly specified work sequence that calls out the content, timing, sequence and intended outcome of the work. EVERY time that work sequence is carried out, the actual content, sequence, timing and outcome is being compared to what was specified. ANY departure from the specified work (or result) is going to trigger some kind of immediate response to correct the immediate issue, and then start the process of problem solving to find the reason this happened. This is jidoka.
  • Although I mentioned timing above, the importance of time is elevated. Taiichi Ohno is quoted as saying “Time is the shadow of motion.” Ohno was a great student. The idea that it is important to study motion itself rather than focusing on time comes from the pioneer Frank Gilbreth. In application, by specifying how long each normal operation should take, and checking the actual timing, it is possible to detect when unplanned motions creep into the work. This is the purpose of takt time and work balance. It is no more, and no less, than a tool for verifying planned vs. actual so that action can be taken immediately if there is a difference.
  • There is a specified amount of work-in-process. Each piece has a reason to be there. There is some means of detecting any departure from that standard, and any departure triggers an immediate response to understand why.

As you scale up from a work cell to an entire factory, these mechanisms scale as well, but the principle is always the same:

  • Tightly specify what you expect to do, when it should be done, who should do it, where it should happen, and how it should happen.
  • Tightly specify (understand) the intended “defect free” result of each step.
  • Have a way to verify, continuously, that what you are actually doing (and when, who, where and how) matches what you planned.
  • If When you DETECT any departure from what you specified, STOP pretending you are still running to plan; FIX or CORRECT whatever got you off plan and get back on plan; then work to understand and SOLVE THE PROBLEM. This is how the organization learns and acquires what Deming calls “profound knowledge” of itself and its processes.

In a complex one-off situation, you might never carry out that plan again. But plan carefully, applying everything you know… all of your expertise. Understand the elemental tasks that you do all of the time. Understand how long each should take. Understand what result you should get at each step.

As you carry out the plan, if when there are unforeseen real world issues, STOP long enough to understand their impact and start asking questions. First, what must we do to get this back on track?

If someone had to improvise, why? What knocked him off the plan or process?

If someone had to finish up work he got from upstream, why? Was the specification for a “defect free” transfer vague? Does it need clarification?

This can go on, but the bottom line is that most organizations with complex processes expect their people to accommodate and cope with noise in the system. They say “every time is different, we can’t possibly plan that well.”

The ones who are getting better every day say “We should be able to plan this perfectly. Why couldn’t we this time?” In simply asking that question, they get better each time they do it.

So – in the context of the original question. When putting together a complex bid and proposal, there are (I presume) steps you routinely go through. This is so even if you are not aware of what they are. Study those steps. Study the intermediate products. Understand where one step ends and the next begins. Understand what must be present (information, resources, etc.) for that step to execute successfully. If, at any point, those things are not there then STOP and understand WHY. Don’t just ask the people who SHOULD have those things to go find them.

You wouldn’t have an assembler on the shop floor hunt down missing parts. Don’t have a professional engineer hunt down information he should have received.

Check, at each intermediate step, that it was done as you expect.

At the end of the process, check that the bid is what you want it to be. If it needs rework (meaning someone didn’t approve it), understand why, and work on what information the process didn’t have the first time through. Next time, get it right.

The proposal itself is packaging. It is also your first cut at the plan for execution.

If you get the bid, and execute your plan, any departure from what you originally proposed should be understood. Why? What happened? What didn’t you see coming? Some things are truly different, and you are only estimating. But compare your actual vs. your estimate so that next time you can do a better job estimating.

There will always be imperfections. The question is in whether the organization chooses to bury them in waste or learn from them.

Accurate Forecasting

Why can’t we get a more accurate forecast from sales?
Manufacturing managers the world over have the same complaint.

Maybe the word “forecast” is tripping everyone up.

A forecast is a prediction. Maybe it is based on some kind of market analysis, maybe even asking the dealers what they think they will sell. It could be based on a lot of things.

Once a forecast is complete, it is regarded as the best guess for how things will pan out, but those things are (felt to be) largely beyond our influence.

We forecast weather. How many hurricanes will we have this season? Will it rain on the outdoor wedding? Tides are forecast (accurately, but we can’t change them).

A competitor’s sales might be forecast, because we really don’t know their plan.

A sales forecast gets put together, approved, agreed, and entered into the data system.

Then two things happen.

Manufacturing bets the farm on it. They order long-lead parts, establish production plans, set factory capacity. They decide, based on that forecast, how much money is going to be spent, whether anything is actually sold or not. Those decisions often have to be made months in advance.

Meanwhile, all too often, sales has forgotten about the forecast, except perhaps, the top line sales figures. They work hard to sell whatever they can. They push for the big order. They offer the world to prospective customers. They will offer discounts, then push for higher unit volumes to close the dollar targets. Many times they operate on a quarterly (or worse) cycle.. as long as they have a great June, then April and May don’t matter so much.

Meanwhile, back in the factory, when April and May have been dry, they get slammed on June 4th, and end up expediting in parts (at great expense), and working overtime (at great cost), to make product that was sold at a discount.

This is no way to make money.

Let’s get back to what I think is the original issue – the word “forecast” meaning “prediction” (or “educated guess”).

Let’s change one word.
Sales Forecast Plan

That changes the entire meaning.

A “forecast” is a prediction of some event we have little or no control over.

A “plan,” on the other hand, is a set of actions which, if carried out as intended, are predicted to give a specific result. This is a different kind of prediction. This is the kind of prediction that an engineer makes. She analyzes her design, applies her considerable understanding of materials, structure, load transfers, then she predicts at what point that design will fail. If it is a brand new design, it is often tested to destruction (like a new airplane wing). This isn’t to test the design so much as to validate the models used for the prediction.

Sales isn’t engineering, I know that. It involves the most complex thing we know about – human psychology.

The sale planning process goes roughly like this:

  • Financial, margin, volume targets to hit the higher level strategy for profit and growth.
  • What must be sold, when, where to hit those targets. There may be more than one set of options.
  • What must be done to achieve those numbers. This includes consideration for:
    • Unit volumes and mix. (Which are really the only thing the factory cares about.)
    • Total profit targets.
    • The margins that have to be held to hit those profits, at those volume and mixes. (Yes, sales is responsible for margins and profit.. how much money the company can actually keep, not just top line results. “We’ll sell it at a loss and make it up in volume” is not a long-term strategy to stay in business.)
  • Then a process of looking realistically at what must be done, what can be done, deciding on a course of action, and producing a detailed plan to carry it out.

That sales plan then plugs into a production plan. Where there are planned fluctuations, we can apply planned levels of buffer inventory – FIFO inventory, not just make-to-stock inventory, to allow a small time disconnect between when it is made and when it is shipped. This is part of heijunka. (This works in both make-to-order and make-to-stock models, only the mechanics differ.)

Now the entire organization can carry out PDCA.
Are the activities in the sales plan being carried out, as planned, when planned?
If not, why not?
Are they producing the results that were intended predicted? (One-by-one confirmation.) No? OK, what have we learned that we can apply to making a better prediction next time? AND, most critically, What else are we doing to do, because we still have to hit the numbers!

And hit the numbers we must. Not by the end of the quarter. By the end of the month to start. Then in two week increments. Then in one week increments. (And all of this assumes you are making and selling something that doesn’t spoil if it is sitting on the lot for a week.)

The sales plan is the production plan for sales. It is not a guess at how well they will do Just like the manufacturing production plan, it is a firm commitment on how they will support the organization’s overall goals. Yes, reality intrudes and plans rarely get carried off exactly as written. But the thinking that went into making the plan, and the commitment to deliver the results, means the organization, as a whole, is prepared to deal with the unexpected and still stay on track.

Is this idealistic? Absolutely. It is pursuit of perfection. But until the thinking is in place, we will be stuck where we are… waiting for something outside of our control and hoping.

The Importance of Heijunka

My friend Tom poses an interesting question to production managers:

“If I ask you to produce different quantities and types of products every day, what quantity of people, materials, machines, and space do you need?”

Of course the answer is usually, at best, inarticulate and, at worst, a blank stare. There isn’t any way to know. Add to this the well-established research of the “bullwhip effect” which amplifies the magnitude of these fluctuations as you move up the supply chain, and it is easy to see the suppliers are really set up to fail.

Then he asks another question:

“If I ask you to produce the same quantities and types of products every day, or every hour, could you then answer the question?”

And, of course, the answer is that this is a “no brainer.” It would be very easy.

So the rhetorical question to ask is: Why does Toyota place such emphasis on heijunka?”
But my question is “Why don’t we all do it?”

Heijunka is a process of dampening variation from the production schedule. In English it is called “production leveling.” It comes in two steps:

  • Leveling the daily workload – smoothing out variations in the overall takt time.
  • Leveling the product mix within the daily work load – smoothing out variations in the demand from upstream processes.

Production leveling, however, is difficult, and the management has to have the fortitude to do it. Honestly, most don’t. They don’t like to deliberately set the necessary inventory and backlog buffers into place. So I’d like to explore some of the consequences of not doing it and then ask if these costs are worth it.

Consider this analogy.

Take a look at what modifications are necessary for a vehicle to traverse a rough, irregular road. The suspension must be beefed up, more power is required, the drive train is far more complex for 4×4. The road itself is unmarked, so the driver does not know where he is or where he is going without sophisticated navigation equipment.

Most of this additional hardware is actually unnecessary most of the time. But it might be needed, so it has to be there… just in case.

The driver of this vehicle is primarily concerned with what is right in front of the vehicle, and far less concerned about what is a mile (or even a few dozen meters) up the road. He will deal with that problem when he comes to it. Driving in this environment requires skill, training, experience, and continuous vigilance. People do this for recreation just for these reasons.

Now smooth out the road. Straighten out the hard curves. Give it some pavement. Put in signs so it is possible to navigate as you go. The same speed can be maintained by a vehicle which is lighter, has less power, a simpler drive system, a simpler suspension. Even though the engine is smaller, it is more efficient because it can run at a constant power output, the sudden accelerations are not necessary. Everything is easier.

The vehicle is much less expensive and much more efficient. The driver’s task is far simpler.

When you allow outside-induced variation to work its way through your system, you are putting potholes in the road. You are introducing sudden turns, sudden changes. Sometimes you are washing out entire bridges. People must be more and more vigilant and they simply miss more things. Their mental planning horizon shrinks to what they are working on right now, and maybe the next job. They certainly aren’t checking what they need tomorrow. They will worry about that in the morning.

The Effect on Materials

Even in the worst managed operations, people generally want to be able to provide what they are supposed to. They are motivated to be “good suppliers.” They also intrinsically understand that if they are idle (not producing) this is not good. Even if they are not provided with the tools and resources to do so, they will do the best they can to succeed – even if those things hurt the overall organization.

(I should note that most “management by measurement” systems actually encourage people to do things that hurt the overall organization, but that is another article.)

When these well meaning people encounter problems, they try to mitigate the effects of those problems with the resources they have available.

  • If their upstream suppliers do not deliver reliably they will add inventory so they have what they need.
  • Likewise, if their upstream suppliers do not deliver good quality, they will add some more inventory to make sure they have enough good material.
  • If there is quality fallout within their own process, they will add inventory and up production to cover that. By the way, that increase of production also increases the demand on the upstream suppliers, sometimes in unpredictable ways.
  • If their customers have irregular demand patterns, they will add inventory so the customers can have what they need, when they need it.
  • If there is batch transportation either upstream or downstream from them, they have to accumulate inventory for shipping.
  • If there are on a different shift schedule from either their customer or supplier, inventory accumulates to accommodate the mismatch.

Do you notice a theme here? The key point is: Without the system level view from their leadership, and without the problem solving support, all they can do is add inventory to cope.

Without leveling, any variation in demand will propagate upstream. At each step, two things happen:

  1. Processes that accumulate and batch orders progressively add to the amplitude of the variation.
  2. Irregularities within each process are added to the variation that comes from the customer.

By the time this hits your supply base, it is a tsunami. First the beach goes dry as it looks like the order base has dried up. (This is why you need to constantly reassure your suppliers with a forecast – because they can’t see regularity in your orders.) Then all of that water comes rushing in at once – and your suppliers can’t cope. Worse, they may have allocated the capacity elsewhere because they were tired of waiting on you. Lead times go up, things get ugly.

But even internally, all of this self-protection just adds more and more noise to the system.
So they add more and more inventory.

For a management team that is reluctant to deliberately add some inventory or backlog buffer to contain sources of variation and protect the rest of the system here is some news: Your people are already doing it, and in aggregate, they are adding FAR more inventory than would be needed with a systematic approach. They can only see the local problems, and each is just trying to be reliable – even if their efforts work in the opposite direction and actually introduce more variation into the system.

The Effect on People

I live in the Pacific Northwest of the USA. A fact of life living here is that, occasionally, the earth literally moves under our feet. I can tell you from experience that this is psychologically unsettling.

In our factories we do the same thing to people when the schedule changes every day. In the name of flexibility we shift requirements up and down. Add to that chasing shortages and hot list jobs around, and the daily work place is chaos. People are not sure if they are succeeding. Or, at best, they declare victory because they were not buried today.

Daily kaizen? That is just not going to happen in this environment. When you start talking about introducing flow, you threaten the self-protecting inventory buffers, and I can assure you that you will have a fight on your hands. Why? Because your people believe they need these buffers to get the job done – the job you want them to do. Now you are taking that away? Are you insane?

This is why it is critical to establish a basic takt as early as possible, then immediately start aligning the expectation to just meeting that takt.

Anything that keeps people from meeting takt becomes a problem and must be addressed. This is jidoka. Heijunka is a block in the foundation of the TPS “house” for a reason. Unless people are standing on solid ground, they can’t even consider anything like “just in time” or “stop and respond to problems” because they are spending all of their mental bandwidth just trying to figure out what is going on hour by hour.

Conclusion

When I was a military officer, we were trained in tactics designed to present our opponent with a constantly changing picture of what was happening. We wanted to inject as much confusion and uncertainty as possible. The mechanics of defeat on the battlefield are simple: The force subjected to this first shifts from action to reaction. They lose initiative, and therefore lose psychological control. Next the horizontal control linkages start breaking down. Each sub-unit starts to feel isolated from the others. They feel less a team and more on their own. Then, as more and more of their attention is shifted to self-preservation, the vertical chain of command breaks down. Each sub-unit is now mentally isolated and can be defeated in detail.

Ironically many factories are managed such that the workers on the shop floor are subjected to exactly these same conditions – and we wonder why they have a cynical view. We are defeating ourselves.

Really Long Takt Times

One question I see coming up a lot in various forums is how to deal with issues unique to very long takt times. By “very long” I usually hear about many hours, sometimes days, occasionally weeks. Because it comes up fairly often, I thought I would take a shot at addressing it here.

I think the biggest hurdle for people to get over is the issues are largely the same as shorter takt times. They are just harder to see because the work starts to lose a human time scale. The trick is to get it back onto a time scale that people can relate to.

By this I mean that a person, generally, loses a sense of how long something is taking once it goes beyond a dozen minutes or so. In contrast, the stereotypical automobile line has a takt of about 60 seconds. Once an auto assembly worker loses 3 or 4 seconds of time, there is really no way she will be able to complete the programmed work cycle without help or stopping the line for at least a few seconds.

As work cycles get longer, though, the work remaining until “done” gets more and more disassociated from “now” and the idea of the necessity to maintain a particular work pace becomes abstract. This is less of a technical issue than one of human psychology. People, in general. tend to believe they can finish something in time long after that is no longer true. (Ask any college freshman working on a term paper.)

The countermeasure is the same as a manager would apply to any long project: milestones.

When the takt times are relatively short, the “milestones” are the takt intervals themselves. Each takt time signals a stage of work that must be complete. If this is not true, the line will (should) be stopped at that point. (Remember – “Never pass along a defect” and this includes incomplete work.) The problem will be corrected, and the cause understood. Oh – actually this is not quite true. A Toyota assembly line has the work zone divided into 10 sub-intervals, and the worker has a good idea what work should be completed at what point.

However, since most of us are likely just beginning – If your takt time is longer than a couple of dozen minutes, then, define the work in stages. In one operation I suggested the following:

Take about 85% of your long takt time, and divide that into quarters. Define what job should normally be complete by the time each of those check points comes up. As an example – if the takt time was 100 minutes, then determine the expected work completion at 20, 45, 65 and 85 minutes. Give the Team Member a way to know where he is at that point vs. the expectation, and a way to call for help if he is off by even a little bit. He should also call for help before that point if he is disrupted by something that he knows will cause a delay.

This is just a starting point to start to stabilize the system and build your support structure. If you reach the point where things are running smoothly at this level of granularity, then cut those time intervals in half.

At each point you will find more problems. The problems are likely to be smaller, but there will be more of them. All of those problems are sources of friction, and therefore wasted motion and time, on your system.

BUT – before you start down this road, have a few things in place first.

  • Establish credibility for the concept that you are genuinely doing this to see problems that are making the worker’s jobs difficult. If you use it, just once, to initiate a negative consequence for “not working fast enough” then forget it.
  • Actually work the problems. This means work them to eliminate the causes. Put in a process for managing the problems, make it visible so that the people working can see you are working on them. Again, this is to maintain credibility. If problems get recorded and sunk into a black hole (like a database in a computer somewhere), then you are not assuring the people on the line that you actually care.
  • Build your immediate responses (escalation) system. This mean team leaders (first responders) who can, and do, respond to help calls quickly. The only thing worse than having no way to call for help is to call and have no one respond. Again, the system loses credibility after about the third andon pull with no response.
  • Don’t worry too much about every detail within the work interval. The important thing, at first is to make sure that the same things get done within that interval. Detailed sequence standardization will come in time.

Summary: The key to managing really long takt times is to break the work into time-based intervals, and manage to those, rather than the entire work cycle itself.