Evaluating the Stability of Tensile Testing System Using Quality Control Charting Techniques

Using statistical process control theory, the control chart was drawn to analyze and judge whether some quality characteristic values were sustained in a controlled state during the laboratory internal quality control. And through analyzing the controlled state, effective measures could be taken in order to ensure that the inspection process was stable and accurate. The quality control samples were tested continuously in a certain time interval and the results were normalized based on the method of mathematical statistics. The quality control charts and moving weighted average control charts of tensile strength, yield strength and percentage elongation after fracture were drawn. Meanwhile, the quality control results were analyzed by using the quality control charts. The results show that compared to the conventional quality control chart, the new developed control chart could not only intuitively and effectively reflect the stability of tensile test, but also improve the ability to find the small data drift.