Investigation of tool wear in alumina micromachining by multi-tip ECDM

Experimental analysis of tool wear in alumina micromachining by multi-tip Electrochemical Discharge Machining (ECDM) technique is reported. Multi-tip tool electrodes having a tip size of 300 µm and length of 10 mm are created in stainless steel by wire-EDM. Experiments are conducted at different tool feed rates, i.e., 0.25 µm/s, 0.50 µm/s, 0.75 µm/s. Tool wear of 3 × 3 array electrode is categorized into three different zones, i.e., outer-most tip, outer-middle tip wear, and central-tip. The experimental results reveal that the outer-most tips are worn out rapidly compared to other tips due to the localization of higher current density and easier availability of fresh electrolytes. The tool wear is severe at a slower feed rate due to prolonged exposure to the higher temperature generated during the ECDM. However, at a higher tool feed rate (≥0.50 µm/s), the tool-tips are in physical contact with the alumina substrate. The central tip has a sideways bending beyond tool travel of 400 µm that would have led to the breakage of thin alumina substrate. The experimental results are useful in understanding the tool wear pattern in multi-tip electrodes during the ECDM process used in the micromachining of alumina and other non-conductive materials.