Tool Load Sensitivity Against Multidimensional Process Influences in Microblanking of Copper Foils With Silicon Punches

Abstract

The continuous trend toward miniaturization of metallic microparts of high quality at low costs results in the need of appropriate production methods. Mechanical manufacturing processes like forming and blanking meet these demands. One major challenge for the application of them are the so-called size effects. Especially, the downsizing of the required manufacturing tools and adequate positioning cause higher effort with increasing miniaturization. One promising approach for downsizing of tools is the transfer of knowledge from microsystems technology. This study shows the process behavior of etched silicon punches in microblanking operations. For the application as tool material especially, the brittle material behavior and sensitivity against tensile stresses have to be considered. These mechanical loads favor wear in form of cracks and breaks at the cutting edge of the punch and thus decreasing tool life. In a special test rig these wear phenomena were observed in microblanking of copper foils. Although, high positioning accuracy between tools and workpiece can be assured within this test rig, scatter of tool life is observable. Therefore, a finite element (FE) analysis of the tool load in the microblanking process with special respect to tensile stresses was performed. Within the 3D FE model multidimensional positioning errors like tilting between punch and die were integrated. Their influence on the tool load in form of increasing tensile stresses is evaluated with respect to the type and magnitude of positioning error and verified by experimental results concerning wear. Furthermore, the effect of small outbreaks at the cutting edge on the process behavior and tool load is analyzed.