Investigating the electrical discharge micro drilling for porous architecture in magnesium alloy

Abstract

Three-dimensional porous architectures (also called scaffolds) of magnesium (Mg) alloys are now highly prevalent for tissue engineering to enable favourable physical and biological environmental support in bone healing. The electrical discharge micro drilling (EDMD) can be projected as an economical manufacturing route for generating micro-perforation or porous architecture in Mg alloys. In the present work, the capability of EDMD is investigated to produce micro-perforation with close dimensional tolerance in ZM21 Mg alloy. The EDMD process variables like; discharge current (Ip), Pulse-on time (Ton), Pulse-off time (Toff), electrode material, electrode polarity, electrode rotation speed (RS), and work height are investigated for micro-drilling in Mg-alloy. The drilling rate (DR), electrode wear ratio (EWR), hole overcut (HO), and circularity are the performance characteristics. The experimental study revealed the significant influence of process variables on performance characteristics. Selecting the combination of EDMD parameters, Ip: 3Amp, Ton: 50 μsec, Toff: 50 μsec, RS: 140 rpm and using copper electrode (diameter 300 μm) with [+ve] polarity, porous architectures with varying porosity are successfully fabricated for Mg-scaffolds.

Keywords

• Electrical discharge micro drilling (EDMD)
• Mg-alloy
• Porous architecture
• Drilling rate
• Electrode wear ratio