3 ms·

High end automated processes can indeed hit extremely high tolerances, but that’s a trade-off on cost (give or take) and often not one the factory is making. I’

High end automated processes can indeed hit extremely high tolerances, but that’s a trade-off on cost (give or take) and often not one the factory is making. I’m reminded of a story about GM, where the top execs would preview drive all the new models - except the ones that were given to the execs had been hand-tuned by engineers to fix the manufacturing slop, so the GM brass was convinced their cars were much better than they were.

ryao 2y ago
I am reminded of the following story: https://www.1factory.com/quality-academy/forgotten-lessons.html https://www.1factory.com/quality-academy/forgotten-lessons.h... Ford had transmissions produced in both the US and Japan, yet the Japanese made transmissions had 1/4 the repair frequency. Their engineers disassembled them to discover why. It turned out that they were both within spec, but the Japanese transmissions had been manufactured to tighter tolerances and had targeted ranges in the specification that resulted in a better fit and superior performance. In this case, the factory had taken it upon itself to improve the design within the tolerances that Ford had specified. Tighter tolerances usually cost more, although economics of scale can bring the price down. Presumably that happened in the case of the Japanese factory. Otherwise, they would not have been able to produce the transmissions at the prices Ford paid them.
- tedunangst 2y ago
  Disappointed the story didn't end with the revelation that the good transmissions were all hand made by monks.
- kragen 2y ago
  Eliminating sources of variation from your manufacturing processes can reduce downstream costs in a lot of ways. The most obvious one is less rework, but also you need, for example, less inventory to buffer variations in production pace. Consequently it's now conventional wisdom that, although hitting tighter tolerances costs more, doing what the Japanese were doing normally costs less.

ryao 2y ago

I am reminded of the following story: https://www.1factory.com/quality-academy/forgotten-lessons.html https://www.1factory.com/quality-academy/forgotten-lessons.h... Ford had transmissions produced in both the US and Japan, yet the Japanese made transmissions had 1/4 the repair frequency. Their engineers disassembled them to discover why. It turned out that they were both within spec, but the Japanese transmissions had been manufactured to tighter tolerances and had targeted ranges in the specification that resulted in a better fit and superior performance. In this case, the factory had taken it upon itself to improve the design within the tolerances that Ford had specified. Tighter tolerances usually cost more, although economics of scale can bring the price down. Presumably that happened in the case of the Japanese factory. Otherwise, they would not have been able to produce the transmissions at the prices Ford paid them.

tedunangst 2y ago
Disappointed the story didn't end with the revelation that the good transmissions were all hand made by monks.
kragen 2y ago
Eliminating sources of variation from your manufacturing processes can reduce downstream costs in a lot of ways. The most obvious one is less rework, but also you need, for example, less inventory to buffer variations in production pace. Consequently it's now conventional wisdom that, although hitting tighter tolerances costs more, doing what the Japanese were doing normally costs less.