Now we come to the sixth way to use a process behavior chart. Here we are going to look at how one group of workers used their average and range chart to improve their process. Their part had only one critical dimension, and this dimension had a standard deviation of only 15 microns. What kind of high-tech product might this be? Read on.

A group of executives from the Body and Assembly Division of Ford Motor Co. were visiting the Tokai Rika plant in Japan when they noticed eight production workers gathered around a process behavior chart “engaged in active discussion.” To the group from Ford it seemed that there must be a problem, which they expected to be an internal production problem, or an assembly plant problem, or a problem of too many rejects. The group’s host inquired about the discussion, and they learned it was simply a routine review of a process that for the past five months had operated predictably, on target, and well within specifications. To substantiate this, the Tokai Rika personnel translated the chart, photocopied it, and presented it to the group before they left the plant. Thus we have a process behavior chart that provides a 20-month window on this production process and reveals how the Tokai Rika personnel used this chart as the locomotive for continual improvement.

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