Enhancing formability in Micro-Incremental sheet forming by a novel stacking method of ultra-thin sheets

Abstract

Metallic foils areused extensively in the microelectronics and avionics industries. However, forming these foils into complexshapes is challenging, due to size-effect. The foils are susceptible to bending and distortion under self-weight as they lack stiffness and fail early during forming. Processes, like drawing, stamping, etc. have been explored at the micro-scale, but they are suitable for simpler geometry and low aspect ratio parts. Micro-incremental sheet forming (μISF) is a new flexible forming process that can be used for micro-scale deformation of foils into complexgeometries with higher formability. This work attempts to improve the stiffness and formability of 100 μm thick CP-Ti Gr2 foils by proposing a unique ‘stacking of foils’ (SOF) approach in μISF. In SOF, multiple foils are stacked together which increases their stiffness and plastic deformation. Experimental results demonstrate that formability is considerably improved by about 21–27 %, with better geometrical accuracy of the micro-parts.