Experimental investigation into tool wear behaviour of line-array tool electrode during the electrochemical discharge micromilling process

• Published in: Journal of manufacturing processes Vol. 72; pp. 93 - 104
• Main Authors: Mishra, Dileep Kumar, Dixit, Pradeep
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2021
• Subjects: Dual serpentine flow field; Electrochemical discharge machining; Line-array tool electrode; Long microchannels; Multi-pass; Tool wear; Long microchannels; Dual serpentine flow field; Line-array tool electrode; Electrochemical discharge machining; Tool wear; Multi-pass
• ISSN: 1526-6125; 2212-4616
• DOI: 10.1016/j.jmapro.2021.10.009

A tool-workpiece gap during the electrochemical discharge machining (ECDM) process is a critical parameter for successfully fabricating microchannels using line-array tool electrodes. Tool wear during the ECDM process increases the tool-workpiece gap and result in non-uniform array microchannel depths or intermittent machining due to reduced heat flux transferred into the workpiece. Hence, proper selection of a tool material that results in uniform tool-tips height/tool-workpiece gap for a longer machining time is essential, especially for the line-array tool electrodes. In this article, the tool wear behaviour of four different materials, i.e., brass, SS304, molybdenum, and tungsten, during fabrication of longer (>15 mm) and deeper (>200 μm) array microchannels using multi-pass ECDM process is reported. The tool wear behaviour at varying machining time/pass numbers was investigated, keeping all other process parameters constant. The experimental results found that the brass electrode's wear rate was relatively faster, and the line-array tool electrode becomes unusable for the ECDM process after 15 min of total machining time. The wear behaviour of molybdenum and tungsten tool materials was similar and resulted in intermittent or no microchannels formation after 35 min of machining time. At the electrolyte-air interface, necking of the tips and subsequent breaking at different machining times was observed for the brass, molybdenum, and tungsten tool materials. Comparatively uniform tips height, microchannel depths, and negligible necking were observed for the SS304 tool electrode after 65 min of machining time. Therefore, SS304 is a suitable tool material for fabricating longer and deeper array microchannels using the multi-pass ECDM process. Moreover, the fabrication of a dual serpentine flow field was demonstrated in the glass workpiece using customized SS304 line-array tool electrodes.
•Tool wear behaviour of 1 × 5 line array tool electrodes made of 4 different materials in the ECDM is reported.•In spite of having lower melting point, stainless steel (SS304) electrodes had lower tool wear than tungsten and molybdenum.•Necking at the electrolyte-air interface was noticed in brass, molybdenum and tungsten, that led to the tooltip breaking.•Tooltip shape change, weight loss and reduction in tip heights were analysed at different machining time.•Using the SS304 electrodes, very long (>18 mm) and deep microchannels were fabricated in the glass workpiece.