Hybrid Micromachining and Microfabrication Technologies

13Material Removal in Spark-Assisted Chemical Engraving for Micromachining

Sumanta Banerjee

Department of Mechanical Engineering, Heritage Institute of Technology, Kolkata, India

Abstract

The fundamental principles underlying the material removal mechanism in Spark-Assisted Chemical Engraving (SACE) are outlined in this chapter. In this process, energy required for machining is provided by electrochemical discharges. Till recent past, material removal in SACE μ-machining was attributed to melting of workpiece. However, recent state-of-art studies underline the important contribution of etching in electrochemical discharge on glass and other amorphous substrates. SACE-assisted micromachining uses either an active cathode (or anode) as tool, respectively in direct (reverse) polarity machining. As the discharge mechanism differs for these machining modes, the machining features and performance also vary significantly. This warrants fundamental understanding of the underlying mechanisms of the material removal processes. Experimental and analytical investigations indicate that several processes contribute to this micromachining mode, which includes electrochemical discharge-assisted melting and vaporization, etching at elevated temperatures, differential thermal expansion of components, random thermal stress cycles, as well as thermomechanical shocks attributed to expanding gases and movement of electrolyte.

Keywords: SACE, micromachining, electrochemical discharge, etching, electrolyte ...