A strategy for low electrode wear in meso–micro-EDM

• A graphite electrode with the cross-section as small as 0.050 mm × 0.035 mm and the length of 1 mm is milled using a planar guided 3-axis milling machine.
• The electrode wear is strongly dependent on the discharge duration for graphite electrodes.
• Generation of a carbonaceous layer on micro-scale graphite electrodes is shown to be feasible for erosion of a number of engineering metals.
• A novel strategy is developed to control the build-up of carbon layer such that zero wear is achieved during erosion with micro-scale graphite electrodes.

Implementation of die-sinking EDM for precision machining of meso–micro-scale features with surface area smaller than 10 mm2 down to 0.1 mm2 is mainly restricted by electrode machining and electrode wear. In this work, micro-scale graphite electrodes with a projection area as small as 0.002 mm2 and 1 mm length have been machined. Process parameter analysis is carried out to analyse the wear behaviour of micro-scale graphite electrodes during erosion. Pulse duration, pause duration and rising current slopes have been found to be the primary parameters affecting the electrode wear. A low electrode wear strategy consisting of the wear neutral pulse packets is developed for erosion of micro-scale cavities and slots using graphite electrodes. Resource efficiency achieved through low electrode wear during roughing enables die-sinking EDM as a potential economic and energy efficient micromachining process.