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Lean Production and TPM
Seiichi Nakajima

The Dramatic Results of JIT and TPM
There is a very simple reason that both JIT and TPM programs have attracted attention - dramatic results. Let us consider an example that shows the full scope of the nature of these results.

Table 1 shows the results of a study conducted by Professor Chitoku Kumaya of Nagoya University of Science and Technology. As the table shows, companies that had fully implemented their lean programs achieved results that could only be called revolutionary: inventory and lead time were cut between 10 and 20 percent of former levels, changeover loss was cut to one-fifth the former level, and the number of control personnel used was halved.

Table 1: Comparative Effects in Companies Implementing Lean

One important fact shown by this table is that companies that had only incompletely implemented their JIT programs reported an increase in changeover loss and in control personnel, despite the fact that there was only a small reduction in lead-time. This is due to the fact that incomplete programs have not established a production base sufficient for reductions in changeover time, and in defects and failures. Herein lies the difference between companies that do not respect lean and those that receive prizes in the field, according to the interpretation made by Professor Kumaya.

Like JIT, TPM also has had revolutionary results for companies that have implemented it. Quantifiable results for recent winners of the PM Prize include drops between 1/50 and 1/150 in the number of instances of spontaneous equipment failure, drops to one-tenth of the former number of process defects, maintenance costs cut 30 percent, product inventory cut 50 percent and the elimination of lost work due to accidents.

In addition to these quantifiable results, there have been other, less tangible, results as well. Some examples include the creation of operators who are well grounded in the basics of their equipment, projects to eliminate failures, defects and accidents, and an overall improvement of the image of the company, which nearly always leads to new orders.

Using Perspective
The need to add TPM to lean has been recognised both in Japan and abroad in recent years, and more and more companies are turning to TPM.

As more and more Japanese companies become engaged in local production, the principal philosophies and methods of lean can be logically expected to become even more global than they already are. At the same time, Professor Kumaya’s research leads us to believe that companies that have not fully implemented the programs will experience a number of difficulties.

By adding TPM to their JIT programs, companies can make further strides in shortening changeover operations, and in reducing defects and failures. The mutual benefits of the two programs will lead to revolutionary results that will be of interest throughout the world.

TPM is not just a Japanese approach. It needs to be instituted on a global basis, along with lean, by all companies that hope to survive the economic hardships of the world to come.

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