By: Scott Watson
Jun 27, 2012 | 5:34 pm
Welcome to Part 7 of E2M‘s 8 part series about Lean. Today we’ll be wrapping up our Case Study: Cars & Liquids Don’t Mix.
In Part 6, the “Lean experts” from Toyota gave the juice manufacturer this recommendation: Close-couple the machines and eliminate all conveyors except what was necessary to move the product from one machine to the next.
The question was if the recommendations were appropriate for a high-speed juice line. The key difference was the between a high-speed line like the juice manufacturer and a low-speed line like Toyota.
With the understanding that a high-speed line can be too lean, fortunately, the juice manufacturer did not experiment with a no-conveyor manufacturing system that was recommended to them. If they had taken that advice, the line performance certainly would have suffered.
The reality of high-speed manufacturing is that micro stops occur throughout the course of a production run. Adding just enough buffer between machines allows operators to deal with a jam while the line continues to run. High-speed manufacturing systems use buffers like cars on the interstate. If you maintain enough of a distance, the car in front of you can slow down for a moment without causing you to change speed.
To function smoothly, a high-speed line needs a minimum amount of buffer. Calculating the necessary buffer is done by tracking Mean-Time-To-Recover, time analysis, or (more recently) use of simulations. This right-sized buffer allows the packaging line under normal conditions, which includes the normal amount of material variance, to function smoothly. The only time the high-speed line will stop with the correct buffer is when there is an abnormal condition.
Can you think of any abnormal conditions that the high-speed line would stop with the correct buffer?
Don’t forget to join us next week as we finish off this series with our conclusive thoughts on buffers and applications of Lean for High-Speed Manufacturing!