Effects of Process Parameters on Forming Forces and Surface Quality in Micro-Single Point Incremental Forming

Micro Single Point Incremental Forming (µSPIF), the process of shaping parts with at least two dimensions smaller than 1 mm, is a promising microfabrication technique known for its near-net-shape capability and high productivity. The growing trend of miniaturization across various industries has led to increased demand for microproducts and microdevices. The influence of forming parameters is critical for improving metal formability, as well as enhancing geometrical accuracy and productivity. Accordingly, this paper aims to examine the influence of forming parameters, such as spindle speed and feed rate, on mean forming forces, force deviations, and their subsequent effects on the formability of 304 stainless steel parts fabricated using single-point incremental forming. Experiments were conducted using 304 stainless steel foil of 50µm thickness, formed with slender forming tools featuring ball-nose tips of 3 mm and 1 mm diameters, both with a tool height of 12.5 mm. Frustrum pyramids were formed, with varying spindle rotation and feed speeds. The analysis was done quantitatively using force and geometric data, along with a qualitative study of the formed surfaces. This systematic approach helped identify the optimal parameters for slender tool applications in µSPIF. The optimal parameters determined were a tool speed of 6000 rpm and a feed rate of 750 mm/min. The results were experimentally verified through successful forming of of a two-shaped structure geometry comprising a hybrid pyramid and cone geometry using the identified tool speed and feed rate.