Monitoring Welding Process Using Demerit Control Chart

This technical report presents a new statistical quality control (SQC) method for monitoring the welding process in ship construction, utilizing a demerit control chart integrated with the Analytic Hierarchy Process (AHP). The report outlines the limitations of the traditional rejection ratio method, which fails to provide a clear indication of process control. The proposed method employs a demerit chart that assesses quality based on a weighted sum of defect sizes, enhancing the detection of welding defects. The study evaluates the performance of the new demerit chart against the rejection ratio method using data from a ship construction project, demonstrating its superior sensitivity to changes in the welding process. Additionally, the report discusses the integration of fuzzy AHP to address subjectivity in weight assignment, thereby improving the accuracy of defect assessments. The findings suggest that the new approach offers a more effective framework for quality control in welding processes compared to conventional methods.