A New Design of Experiment Method for Trim Dies Considering Fatigue Failure
In automotive body manufacturing, the dies used for blanking, trimming, and piercing are subject to harsh and demanding conditions, including high-impact loading and a large number of cycles. As the strength of sheet metal continues to increase, the service life of trim dies has become a major concern for the industry. To address this issue, this study conducted a comprehensive comparison of the fatigue lifetime of trim dies produced using different manufacturing processes, which involved two distinct materials (wrought vs. cast), two different die heat treatment methods (induction-hardened vs. through-hardened), and analysis of the effect of edge weld repair on fatigue lifetime. An accelerated trimming simulator test is developed to cyclically load and assess the cumulative damage evolution of the cutting edge of a die specimen at a set number of cycles. The evolution of edge damage areas and volumes were used to compare and rank the fatigue performance of each studied condition. A new statistical model is developed to systematically analyze the effects of different routes on fatigue damage over time considering process uncertainty. Microstructures and hardness were analyzed to provide metallurgical explanations of the test results. Suggestions to improve trim die performance and areas for further study are provided.
