Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Influences of Bend Severity, Tool Shape, Forming Wall Angle, and Stepdown Size on Pillow Defect of Stainless-Steel Sheets in Single Point Incremental Forming

Kristian Michael Hai Xiong Tan, Wenting Lia, Kai Soon Fong and Suwat Jirathearanat

Singapore Institute of Manufacturing Technology, Agency for Science, Technology and Research (A*STAR), Singapore 637662


Aluminum alloys are lightweight and ductile, and thus widely formed in single point incremental forming (SPIF) technology. Comparing to aluminum alloys, stainless steel sheets are more difficult to deform because pillow defect or bulging defect can easily occur during SPIF process. Pillow defect generated at the sheet center during SPIF process is a major forming limitation that affects the part's formability and increases the forming load. This study aims to systematically investigate the influences of bend severity, tool shape, forming wall angle, and stepdown size on the formation of pillow defect of stainless-steel sheets in SPIF via experiments. Bend severity is the ratio of sheet thickness to forming tool diameter. A series of forming SPIF experiments are carried out on both stainless steels, including grades SS304 and SS316L, to form parts with varying forming wall angles. Forming tools with different shapes are utilized, including hemispherical and flat end tools. The control solution of pillow defect of stainless-steel sheets is analyzed and explored by physical results. Hence, our study advances the in-depth understanding of formation of pillow defect of stainless-steel sheets and further drives the development of single point incremental forming technology.

Keywords: Pillow effect of stainless-steel sheets, single point incremental forming, stepdown size, bend severity, forming wall angle

PDF Download