To ensure product quality, we must strengthen the quality control of the production process. Quality control is the operational technique and activity taken to meet the quality requirements. The aim is to ensure the quality of the product in order to monitor the process and to exclude factors that are not satisfactory in all stages of the quality ring. Whether it is a semi-finished product or a final product, their quality can be described by the quality characteristics around the size of the design target value fluctuation. If the fluctuation is smaller, the higher the quality level. When each quality characteristic value reaches the design target value, that is, the fluctuation is zero, at which time the quality of the product reaches the highest level, but in fact it is never possible. So the quality control of the production process must be carried out to minimize fluctuations.