Quality Control in a Semi-continuous Polymer Production Process

Abstract In many processes, when the sources of product quality variation are unknown and/or uncontrollable, the quality control system consists of several checkpoints along the production line to keep an eye on product quality. Sometimes similar tests are carried out at subsequent checkpoints. In a semi-continuous polymer production process, the historical records from such checkpoints are used to determine the possibility of reducing the number of measurements within and/or between the checkpoints. A number of statistical analyses, mostly graphical tools (e.g., histogram, control charts, scatter plot matrices, and biplots) are applied to the data. As a result of these analyses, some correlations among the measurements are found. It is also shown that a change in the focus of the quality control system can assure long-term process improvement.