Monday, October 31, 2011
I consulted in a plant that had a large machine that cut rubber tubing into pre-determined lengths. Next to the machine, I spotted a large wire container with cut tubing lengths. It was labeled with a red tag with the word REJECT visible from twenty feet away. The detail on the tag revealed that the tubing contained in this container had been cut too short. It was probably going to have to be scrapped.
I asked why the tubing had been cut too short. Probably human error in setting the machine, I was told. The specs were not entered correctly and no one noticed until a full container had been cut. We formed a work group to find a way to prevent this problem from every happening again.
We discovered that the internal customers for these products were two assembly lines. Tubing that was too long could easily be cut down to size. Tubing that was too short could not be used because it did not reach the two points in the assembly that needed to be linked.
We quickly came to the idea that the tubing was quite easy to cut, so why not cut it just-in-time. The team designed a guillotine (actually a small paper cutter), mounted it on a bench with a channel and a stop that measured the tubing to the required length, making it easy to cut just one piece when it was needed. The roll of tubing was too large to have on the assembly line. We cut off enough to supply the line for one day and rolled it onto a smaller reel. Our arrangement worked well for a week on the first line. After that we duplicated the process on the second line.
Later the company negotiated with the supplier and was able to get tubing in smaller rolls suitable for putting directly on the assembly line. Within the company there was some resistance to taking a “perfectly good” machine out of service, when it was still being paid for. When I toured plants in Japan that were practicing lean manufacturing and continuous improvement, I saw several yards filled with equipment covered by tarps. We were told that this was equipment taken out of service by efforts to make processes lean and reliable.