Kamigo Engine Plant (1983)
Ohno's Masterpiece
Layout
The Kamigo layout placed each machine adjacent to its upstream and downstream operations. Work could then flow directly through a series of machining operations. There were no significant inventory banks between operations. This eliminated the need for conveyors and fork trucks.
Simple Transfer Devices
Kamigo used a wide variety of simple transfer devices that moved one part at a time from one operation to the next. This was made feasible by the layout that placed these operations close together.
Autonomation
Defects are another reason for inventory banks. An automated machine that begins to produce defects may produce large quantities before being discovered and stopped. Just like a breakdown, this single problem would quickly halt the entire plant without inventory banks to keep other equipment running.
Autonomation uses a variety of ingenious mechanisms to detect defects, jams and other problems and then halt the offending machine. Autonomation is also used to control the small inventory between machines and shut down machines that operate faster than their upstream or downstream neighbors.
Because of the lack of inventory and automatic stopping mechanisms, problems in any machine quickly shut down other machines until the shutdown spread.
Jidoka
Jidoka was also used extensively at Kamigo. Jidoka refers to the intentional stoppage of an entire production line when a defect or other problem arises.
A Personal Recollection
In 1983 I visited Toyota's Kamigo Engine Plant. It was, at that time, the most efficient automotive engine plant in the world. My first surprise was the American-built machinery. Greenlee, Hydro-Mat and Cincinnati were among the names on equipment.
It seemed, at first, like returning to the Ford plant where I had worked fifteen years before. But, not quite: at Kamigo there were few fork trucks, no overhead conveyors and very few workers.
As I looked around for overhead conveyors, very common in U.S. auto plants, I noticed only a few abandoned conveyor lines.
From an elevated walkway, we saw almost the entire machining area. I observed only a half-dozen or so workers, a single fork truck and no inventory banks.
What had Toyota done to achieve this? The basics at Kamigo were similar to the usual descriptions of Lean Manufacturing. The emphasis and specifics differed because this was engine machining rather than assembly or stamping.
Total Productive Maintenance
One reason that U.S. automotive plants had inventory banks between operations is that the equipment of that time was not reliable. If the machines had been closely linked, as at Kamigo, a breakdown on one machine would quickly stop the entire plant.
The solution for Toyota was Total Productive Maintenance (TPM). TPM includes Preventive Maintenance in which components are inspected and replaced before failure. It also includes thousands of engineering improvements to increase Reliability, increase Mean-Time-Between Failure (MTBF) and decrease Mean Time to Repair (MTTR).
These concepts did not originate at Toyota. The difference was the intensity and tenacity in their application.
Problem-Solving Culture
This system only worked because of Toyota's extreme version of problem-solving culture. In this culture, work stoppages are not avoided-- they are deliberately provoked. A stoppage exposes a problem. Solving the problem-- completely, permanently-- improves the operation and sharpens the skills of employees. Approached properly, stoppages and the subsequent problem solving are like capital investments. Immediate production is sacrificed for long-term productivity. See also "The DNA of Toyota."
References
MONDEN, YASUHIRO, Toyota Production System, Third Edition, Industrial Engineering & Management Press, Atlanta, Georgia, USA, 1998.
OHNO, TAIICHI, Toyota Production System- Beyond Large Scale Production, Productivity Press, 1988.
SPEAR, STEVEN, The Essence of Just In Time, http://www.hbs.edu/research/facpubs/workingpapers/papers2/0102/02-020.pdf
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