Fabrication of texturing tool to produce array of square holes for EDM by abrasive water jet machining

Abstract

In the present work, a novel abrasive water jet machining (AWJM)-based tool fabrication strategy has been proposed and implemented to make electrical discharge machining (EDM) tools for large-area texturing. The novelty of the work lies in the path strategy proposed for jet movement that moves along two raster paths placed at 90° to each other. By using this path strategy, micro-tools of EDM for machining arrays of square holes were fabricated by AWJ milling process. Based on selected parameters of AWJ process (step-over, traverse speed, path strategy), micro-tools were fabricated on brass and copper sheets. The quality of the kerf obtained during machining by AWJ is conventionally measured using the taper angle. It is explained here how this kind of measurements fall short of quantifying the quality of blind features generated in modern applications of AWJM. These generated features can be accurately measured using highly sensitive techniques of 3D optical profilometer. Based on these measurements, a model based on two performance indices, namely Area-Based Performance Index (API) and Curve-Based Performance Index (CPI) were introduced to analyse such fabricated tools. The technology of large-area texturing to make the overall process fast, by producing high-quality tools in less time, has been demonstrated by using the proposed methodology. Performance of such fabricated tools was investigated by performing experiments on EDM machine. Arrays of square blind holes (texture) were made on stainless steel and Ti-6Al-4V alloy sheet using Die sinking mode EDM. The depth of texture was measured through 3D optical profilometer and was found to be in the range of 10 to 100 μm. The dimensions of textured features were found deviating from the tool dimension due to taper present on sidewalls of micro-tools produced through AWJM.