Research on the characteristics and reliability of using glass dies for metal forming

Abstract

Micro-EDM is widely applied to fabricate micro metal dies but suffers from narrow discharge gaps that hinder debris removal and induce short circuits. This study evaluates glass dies as an alternative for micro-forming, leveraging their geometric flexibility and intrinsically smooth surfaces. We focus on surface roughness of formed parts compared with products made using Wire-EDM steel dies. Metallic dies with four surface conditions (unpolished, smooth, near-mirror, and mirror; corresponding to #400, #1000, and #2000 sandpapers) were benchmarked against two glass-die architectures: fully glass and semi-glass designs. We combined finite element simulations with dry double-cup extrusion (DCE) experi-ments to assess interfacial friction, flow uniformity, and product finish. Results show that components formed using glass dies achieve average surface roughness [Ra = 0.1-0.4 mu m], comparable to metal dies polished to #1000-#2000, with supe-rior smoothness and lubricity under dry conditions. Glass dies increase the real contact area by removing initial micro-voids at the billet interface, reduce the need for polishing or coatings, and enable precise material-flow control through adjustable positioning and alignment. Overall, glass dies constitute a cost-effective route to high-quality micro-formed parts with minimal post-processing