Investigating the effects of electrochemical discharge machining (ECDM) on the dimensional accuracy and surface integrity of the PDMS microchannel

In this study, the electrochemical discharge machining (ECDM) process was used to fabricate a microchannel on polydimethylsiloxane (PDMS), which is able to fabricate channels on the non-conductive materials at low cost and acceptable material removal rate (MRR). One of the main advantages of this method, in addition to much less time and cost, is the possibility of achieving high depths (up to 1000 mu m). For this purpose, the effect of electrolyte concentration, rotational speed, feed rate, and machining voltage on the surface quality and surface roughness was investigated in the PDMS micromachining. It was found that the ECDM is capable of fabricating the channels with the surface quality similar to lithography. Also, with increasing the machining voltage and electrolyte concentration, the MRR increases and the possibility of mechanical contact between tool and workpiece decreases. Increasing the machining voltage and also the electrolyte concentration changes the machining regime from contact machining to electrochemical machining. Increasing the machining voltage from 38 to 42V increases the channel cross-section by nearly 40%. Also, the surface roughness increases by 36% with increasing the voltage from 38 to 42 V. Changing the rotational speed from 0 to 10,000 rpm, due to the reduction in the thickness of gas film, reduces the side sparks and concentration of the sparks on the bottom of the tool, which reduces the surface roughness. The Response Surface Method was used to achieve a mathematical model between inputs and outputs. The model represented a Quadratic Equation to predict the outputs.