The automobile industry, of course, has all of the operations - stamping, painting - that are inherently batch. Once they had a level demand from assembly, they started progressively attacking the reasons for running batches.

In stamping, it was mainly to attack changeovers for dies - SMED - so that they can run progressively smaller batches. In paint, for a long time, they batched colors, then re-sequenced the bodies through the assembly line - recognizing that the inventory between paint and assembly was because of unsolved problems.

Recently they developed a cartridge based paint technology that allows them to switch colors on a unit-by-unit basis, so that is gone… but that isn’t the point. The point is that they did not use assembly batching as a “reason” why they could not level paint.

As for utilization, it is a very poor measurement as, typically, optimizing utilization at any operations results in larger batches and more overproduction, higher usage of working capital, more vulnerability to damage, more storage space, greater need to schedule, track, count, re-sequence, etc. I’ll work up a piece about optimizing batch sizes in the cases where the single-part run time is small vs. the takt and vs. the changeover.

It is about leveling, first, the workload experienced by the main line. Sometimes you have to get creative and introduce time-based units of work that don’t necessarily correspond 1:1 with units of production.

IF you can manage to also level the mix - that is introduce at least the options that impact cycle time in a level manner, then you can have an easier time on the main line PLUS, you allow upstream feeding processes to see a more level signal as well.

THANKS for the comment! As I said to someone else, it is nice to know people actually read this stuff.

TPS is a time based system and if time is level your floor will be level. Inventory is used to buffer either as raw or FG’s. The less the better.

If your through-put time is less than your customer L.T. leveling is easier, and MTO should be the goal.

But how do you level a factory that has varying C.T’s because of different options offered on its product. Some say develop seperate lines to dedicate different SKU’s, this works if the volume mix (pattern) can be maintained.

What I have done is level by time not by volume and smoothed my processes. the work content in time is the same. this only works if the through-put time is less than the customer L.T.

Ultimately, though, it comes back to the core purpose. The *objective* of heijunka is to meter work into the system at the same rate you expect it to actually get processed.

In the graphics and printing industry (I took the liberty of looking up your URL), you probably do at least a cursory job of estimating how long a job will take. If you were to set up some kind of time slotting system, and have each job occupy the estimated amount of time, then you would be able to apply the CHECK of PDCA to your process. You could tell if actual work was running ahead or behind your estimate, and intervene / adjust as necessary.

If you continuously compare actual time with estimated time and use that to improve your estimating process, then you get better and better at predicting.

Even complex jobs often break down into assemblies and sequences of routine tasks. Where each total job may be unique, the underlying tasks are things you know and understand. This is why your team is expert at doing these things.

For truly complex tasks - requiring a project plan - I highly recommend Goldratt’s “Critical Chain” methodology. Google it, you will turn up a lot of material.

How would you go about introducing this in an environment with numerous takt times, depending on the project, customer, etc.?

A pessimist believes the glass is half empty.

An optimist believes the glass is half full.

An engineer would tell us the glass is twice as big as it needs to be.