Optimal Zero-Defect Solution for Multiple Inspection Items in Incoming Quality Control

This paper addresses the issues related to inaccurate inspections and high costs in incoming quality control. Incoming quality control refers to the initial inspection process that verifies whether externally provided products, materials, or services comply with specified quality requirements. Traditional methods inspect each item in sequence for a given part and terminate the inspection upon detecting a non-conforming item before proceeding to the next part. To reduce inspection times, we propose a novel approach termed ‘selection of minimal inspection items’, which formulates the selection of inspection items for a batch of parts as decision variables. This approach ensures that all non-conforming parts are detected while minimizing the total number of inspection items. We identify all the inspection items in the initial batch that cover all the non-conforming parts, then develop a set-covering approach to select the minimum inspection items that cover all non-conforming parts. Subsequently, the next batch of parts is inspected using the selected inspection items to identify as many non-conforming parts as possible. Compared to traditional inspection techniques, this approach demonstrates greater cost-effectiveness. Furthermore, we conduct experiments under scenarios with varying numbers of parts and inspection items across different batches to achieve zero-defect inspection, which ensures all non-conforming parts are identified and eliminated through systematic quality control procedures. Algorithms and programs are developed to implement the reported approach. The experimental results show that the proposed approach significantly reduces inspection times while maintaining high quality.