Toyota Production System

1. Overview of the case

In July 1988, Toyota Motor Manufacturing, U.S.A. (TMM) began volume production on a 1,300 acre site in Georgetown, near Lexington. TMM adopts the Toyota unique Toyota Production System (TPS) for production management.

In March 1992, TMM started producing wagon versions of the new Camry exclusively within Toyota's worldwide plant network. After that, Doug Friesen, the assembly line manager met the seat problem: Cars with seat problems accumulating off-line, and the production run ratio was dropped from 95% down to a meager 85%, an alarmingly high level of off-line vehicle inventory, and the sales company was not getting cars on time as promised.

2. Toyota Production System

The Toyota Production System (TPS) evolved as Toyota's answer to the challenge to produce cars meeting diverse customer preferences with flawless quality. TPS aimed at cost reduction by thoroughly eliminating waste and it provided two guiding principles to facilitate this critical process: JIT and Jidoka.

For principle JIT, it is short for Just-In-Time (JIT) production: produce only what was needed, only how much was needed, and only when it was needed. Any deviation from true production needs was condemned as waste. Tools such as heijunkn and Kanban were used for JIT. Kanban is used to keep information flow as close to the physical flow of parts as possible. Parts were thus pulled from downstream based on actual usage, rather than pushed from upstream based on a planned schedule remote from the shop floor.

As for principle Jidoka, it means make any production problems instantly self-evident and stop producing whenever problems were detected. In other words, jidoka insisted on building in quality in the production process and condemned any deviation from value-addition as waste. The purposes of jidoka tools were to aid immediate problem detection and facilitate visual control. If a worker found any problem, he or she pulled the andon cord to alert the team leader, and the leader then rushed to that work station and check/resolved the issue.

3. Solutions of the seat problem

Seat is a soft and easily broken part. During installation, a hook protruding from the back of that part was to be snapped into the "eye" of the body. But the hook had been changed from metal to plastic, which made it more easily to be broken.

To address the seat problem, Doug needs to do the followings.

Firstly, Doug needs to confirm whether the seat problem was caused by the engineering for the part. Tsutsumi, the Toyota factory in Japan which used the identical engineering drawings for the part, had not reported the same problem, so it seems the engineering issue could be excluded from the root cause investigation.

Secondly, since all TMM seats were provided