塑身与公差 Slim and Tolerance
One of the steps in controlling quality is to control tolerance. This is why quality should be built in product design. Tolerance will directly influence the consistency, stability, reliability and functions of products. It is easy to design tolerance, yet it is difficult to control the tolerance in a limited range. This is why America cultivated over ten thousands of engineers studying the control in statistical processes to ensure the quality of military products during the 1940s. The aim to control statistical process is to minimize the product defects which exceed the tolerance, and to inform the engineers of the investigation reasons to take precautions via the form of graphic trend in advance before producing defective goods.