It's a crime to overproduce

What the Toyota production system seeks is a total elimina­tion of Waste.

We say that "a manufacturer's profit can be found in the way he makes things." It reflects our philosophy of attaining a cost reduction through the elimination of wasteful operations. There are many types of wastes. At Toyota, in order to proceed with our man-hour reduction activities, we divide wastes into the following seven categories:

1. Waste arising from overproducing

2. Waste arising from time on hand (waiting)

3. Waste arising from transporting

4. Waste arising from processing itself

5. Waste arising from unnecessary stock on hand

6. Waste arising from unnecessary motion

7. Waste arising from producing defective goods

The most common sight found in many workplaces is the excessive progression of work. Everything moves too fast. Normally, it must be consigned to Waiting, but workers proceed to the next stage of work. Thus the time that is supposed to be wait­ing time becomes hidden. When this process is repeated, materials or parts produced accumulate in between or at the end of the pro­duction line, creating unnecessary stock on hand. To transport this stock or to rearrange it for storage requires creation of another type of work. By the time this process takes its course, it becomes more and more difficult to find where the wastes are.

Under the Toyota production system, we call this phe­nomenon the waste arising from overproducing. Of the many infractions of wastefulness, this is Considered by far the worst offense.

The waste arising from overproducing is different from other wastes, because unlike other wastes, it overshadows all others. Other wastes give us clues as to how to correct them. But the waste arising from overproducing provides a blanket cover and prevents us from making corrections and improvements.

Thus, the first step in any man-hour reduction activity is to eliminate the waste arising from overproducing. To do so, produc­tion lines must be reorganized, rules must be established to pre­vent overproduction, and restraints against overproduction must become a built-in feature of any equipment within the workplace.

Once these steps are taken, the flow of things will return to normal. The lines will produce one item at a time as needed. The waste becomes clearly discernible as the waste arising from time ion hand. When a production line is reorganized in this fashion, it becomes much easier to engage in the activity consisting of "elim­ination of waste — reassignment of work — reduction of person- pel." The waste arising from time on hand (waiting) is created when a worker stands idly by an automated machine to serve as a watchman, or when he cannot do anything constructive manually bccause the machine is running.

I his waste is also created when the preceding process fails to deliver parts needed in the present process, thus preventing work- fi'H In the latter from working.

In the illustration below, a worker is assigned to each of the machines designated as a, b and c. In this process, the worker stands by idly while the machine moves. He cannot work, even if he wants to, and there is a waste arising from waiting.