Shop flow

Enhancing efficiency in the workplace by carefully planning shop layout. January 16, 2002

I am trying to improve the flow through our shop. Any suggestions on where to start and what I should read?

Forum Responses
This is a serious undertaking that is best served by close and consistent analysis. You must document what really happens. Time studies teach you to look at handlings of all kinds as a vehicle for process reduction.

Here are three things to think about:
1. Material flows like a river through process. Material, moving like water, will flow fast here and slow there. You must account for these different surges and swells, making space for the events to occur as a matter of course.

2. Reduce touches: a part should be touched as few times as possible in process, while a complete and well-done process is maintained.

3. Attack steps: how frequently and how far do your people move to accomplish what they do? Two steps eliminated at a drill may allow 50 additional parts to be processed every day.

Look for negative value and eliminate it. Negative value is anything you do that your customer did not pay for.

Jon Elvrum, forum technical advisor

Ever hear of "the theory of constraints"? Sometimes less is more. Start at the last step in your process and work backwards. You can't start from the first step and make it faster if the next step can't handle it. So the backwards process tells you your maximum volume given current tooling and man power.

I'll go a little deeper into the theory of constraints.

Read "The Goal" by Eli Goldratt. Goldratt doesn't promote "flow" in his writings. Changes in plant flow can, however, be one effect of realigning your Thinking Process. It is a book of logic that helps us focus on the cause of our problem.

You'll learn three things:
1. What to change.
2. What to change to.
3. How to cause the change.

There are two books, by Eli Goldratt with others, that amplify the work in The Goal. The first is a handbook called The Race. Dr. Goldratt began a periodical called the Theory of Constraints which eventually was re-formatted in his third book, The Haystack Syndrome. The three works teach about CCR's -- capacity constraint resources. A CCR is the slowest part of process, when everything is going well. There is no point running any part of a system faster. Understanding this is an enormously empowering principle.

Jon Elvrum, forum technical advisor

Goldratt has published a couple more books since the ones mentioned. "It's Not Luck" deals with marketing and its relationship to manufacturing. "Critical Chain" deals primarily with project management. "Necessary but not Sufficient" deals with fast changes in technology.

There are quite a few discussions on the Theory of Constraints in the archives.

I redesigned my shop by drawing a scaled floor plan and inserting scaled machines and stations within the envisioned workflow. I had a door that raw materials came into and finished products went out of. I set up areas for 4x8 raw panel production, solid wood milling, panel processing (boring holes), face frame assembly, cabinet assembly and installation of doors and drawer fronts. After it was all done I only had to make one small change (switch two pieces of equipment around), and it works great. The best thing I did was separate the panel cutting from solid wood milling. We used to use a Delta Unisaw for everything, but after the purchase of an Altendorf, I saw new possibilities.

My shop is small to medium size (4000 sq. ft.) with 2 guys beside myself. Since this upgrade, our production is through the ceiling. I attribute this to three things. Employees are excited about getting me out of the shop and into the office. Upgrading with new equipment that produces consistent quality cuts. Logical workflow that takes into account our method of cabinet construction.