Effects of process parameters on thickness thinning and mechanical properties of the formed parts in incremental sheet forming

Incremental sheet forming (ISF) is a promising method for forming metal sheets, by which parts can be manufactured without the use of dedicated dies. However, the process has not been widely used for industrial application due to the unsatisfactory service performance of the formed parts. This paper focuses on improving the thickness distribution and mechanical properties (e.g., hardness, yield strength, and tensile strength) through process optimization. The response surface methodology with a Box-Behnken design is used to investigate how different process parameters affect the thickness thinning and mechanical properties. A set of experiments with 15 tests for pyramid-forming process is performed, and three parameters including step-down size, sheet thickness, and tool diameter are considered. The results show that the maximum thinning rate is lower with larger step-down size and larger tools. In addition, compared with the initial sheet, the values of hardness, yield strength, and tensile strength have been increased considerably due to the strain hardening. The present work provides useful guidance in improving the product quality formed by incremental sheet forming.