Improvement of Overlapping Workpiece Detection System for Use in the Stamping Process

In this study, a double-sheet detection system for automated metal stamping is developed and modeled. This study aims to address the issue of die damage caused by overlapping workpieces (double sheeting), a significant contributor to production line stoppages. The proposed solution involves a control system utilizing a programmable logic controller (PLC), combined with inductive proximity sensors installed on the die, for real-time processing of workpiece status. The system is designed to immediately halt machine operation upon detecting any abnormalities. The experimental results demonstrate that the developed system successfully reduced double-sheet incidents from one occurrence to zero and eliminated production downtime (reducing it from 4 days to zero), resulting in a total of 32,972.26 USD saved in potential damage costs per incident. Furthermore, the system reduced the production cycle time from 11 s to 9.5 s per piece, increasing the production capacity by 1240 pieces per day. The economic assessment indicates that an initial equipment investment of only 483.2 USD yielded a return on investment (ROI) of 6723.73%, a payback period of 5.35 days, a net present value (NPV) of 89,333 USD, and an internal rate of return (IRR) of approximately 6830%. These figures demonstrate a very high level of economic feasibility. Therefore, this system is a cost-effective, reliable, and practical approach to enhance productivity and sustainably support the Smart Factory concept in the metal stamping industry, aligning with the automotive parts manufacturing industry.