Thursday, October 31, 2002

Flow vs Batch

George Koenigsaecker of Simpler Consulting describes nine ways that Lean doesn't make sense. His first point-counterpoint:

"Batch production vs. 1 piece flow"

Why do we want to batch things together? I look at my is full of "Batch", translated as "I'll get to that when I can" or "I'll batch all those annoying little tasks together in one lump" or "I'll file all this stuff when I get around to it."

It's no different when we manufacture things. We want to lump all the same size trusses together, even though the timing of the orders may be quite different. Try as I did, I had little luck getting our wonderful pie-making volunteers to make one pie at a time.

I wonder if it isn't genetic, to some extent, or behavorial, found in our agricultural roots. We want to gather food when there is food to be had. I drive past massive piles of corn on the ground these days as the Indiana harvest season comes to a bountiful end. "Batch" surrounds us.

Flow, on the other hand, does not seem as evident. Probably for the very fact that flow, by definition, is moving. Thus, it doesn't stay in place very long. You can't go see "flow" nearly as easily as you can go see "batch." There is evidence of my work when I make a big pile of something. There is no remaining evidence if I make what the customer wants, just as he/she asks for it.

When I was at Wiremold in August, I arrived just before 5pm on a Monday, due to flight delays. One of my hosts, Hans Cooper, gave me a quick tour of the facility. Now, the production associates end their day at 4:30pm, so the plant was quite empty. Hans proudly showed me some of the assembly cells he had helped revamp earlier in the year. "Let me show you some of our surge suppressors that we make here," he said proudly. Then, he looked and looked...none were to be seen. "Wow, I guess they are all shipped." That was flow. No finished was all packaged and on a truck, heading for the customer. For the entire week I was there, the only time I could see product was during the work day. Even then, I had to look fast, as it quickly flowed through the cell, into a box, then onto a truck, backed up to the shipping dock.

Yeah, Batch feels better. Flow pays better. We take our pick.

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