Derivation of Guidelines for Reliable Finishing of Aluminium Matrix Composites by Jet Electrochemical Machining

Abstract

The Collaborative Research Centre SFB 692 at Chemnitz University of Technology is focused on aluminium-based light-weight materials in safety-related parts and components. One field of activity are aluminium matrix composites (AMCs). Thereby, the manufacturing, the mechanical properties, the economic opportunities and challenges as well as the machinability are investigated. One of the research focusses is the finish-machining of AMCs by Jet Electrochemical Machining (Jet-ECM).Therefore, one objective is to achieve guidelines for reliable machining of AMCs by Jet-ECM. In a first step the dissolution characteristic of EN AW 2017 with 10% of SiC particles, which was manufactured within the SFB 692, was analysed by help of a microcapillary cell, applying a sodium nitrate electrolyte. Furthermore, Jet-ECM was used to generate point erosions using different pH-neutral electrolytes, namely NaNO3 and NaCl. AMCs made of the aluminium alloy EN AW 2017 with 0%, 5% and 10% SiC particles were machined with a maximal voltage of 25V.In the current study the parameter field is extended further. The dissolution characteristic by using the pH-neutral electrolyte sodium-bromide is analysed and the voltage range is set to 60V. Those experiments show, that each electrolyte causes a specific dissolution characteristic. Based on the experimental data, guidelines for a reliable finishing of AMCs by Jet-ECM are derived. The resulting guidelines can be used to predict the depth of the point erosions as function of particle fraction, the applied voltage and the machining time, with respect to the used electrolyte.The statistical evaluation of the guidelines show, that the applied voltage and the machining time are the dominant factors to control the dimensions of the point erosions. Whereas the particle fraction has a minor effect on depth and width.