Straightness Accuracy Estimation of Different Cavity Geometries Produced by Micro-electrical Discharge Milling

The purpose of this paper is to present the results of an investigation on the straightness achievable on three cavities: channel, square and cross-channel (square pillars). The steps included machining of cavities in series of three having a nominal dimension of 1000 µm on a steel sample using 200 µm tungsten carbide electrode in micro-electrical discharge-milling (µ-ED-milling). An Olympus optical microscope was utilized to examine the geometry of micro-cavities. The Least Square Method (LSM), which is commonly used in metrology for fitting reference elements, has been used. The LSM solutions for the primary set of data points obtained through Olympus Analysis Five software measurements were calculated to find the achievable straightness. It was found that straightness tolerance of square pillars (19.19 μm) is better than microchannels (31.33 μm) and far better than square geometries (50.66 μm).