Research And Application Of Statistical Process Control Method Aiming At Various And Small Batches Production With Small Shifts

In this paper, the characteristics of small batch production are illustrated. The application status of statistical process control (SPC) on this production method is summarized. Base on these analyses, it is concluded that the traditional control chart is not suitable for the SPC of small batch production, some problems like setup difficulties or relatively insensitivity to small shifts can happen. The universal control chart is put forward to solve the problem of lower quantity of samples with the analysis of the characteristics of the universal control chart.Base on the analysis of small-shift quality control using traditional control chart, the defects of lower checkout rate are illustrated, so the CUSUM control chart and EWMA control chart are put forward. The principles and techniques of the CUSUM and EWMA are illustrated separately both in theory and example. The conclusion is that the CUSUM and EWMA are two very effective alternatives to the traditional control chart may be used when detecting small shifts. The feasibility of applying standard transportation into the CUSUM and EWMA is discussed both in theory and example. With the compare of CUSUM and EWMA, it is found that the CUSUM is more sensitive to the shifts between 1 and 1.5 deviations, while the EWMA is more sensitive to the shifts lower than 1 deviation, then a combined SPC method of universal control chart and CUSUM control chart and EWMA control chart are put forward to solve these problems which is also illustrated theoretically and validated by case study. The steps of using the combined SPC are concluded. A production process management system with a master module of quality statistics and analysis is formed and illustrated using IDEF0 model-forming method. The module of quality statistics and analysis is illustrated while the function of this system is explained.At last, the conclusions of this paper are given; the further research and investigation are suggested.