The Design and Fabrication of an Electrochemical Machining Test Apparatus

The removal of residual casting material from gating has traditionally been performed by abrasive grinding techniques. However, high amounts of belt wear can occur when working with high strength alloys, especially those typically seen in the aerospace industry. An alternative machining process called electrochemical machining (ECM) uses electrolysis to precisely remove material at high rates. ECM has many advantages over conventional grinding: no tool wear, no induced mechanical or thermal stresses, and high removal rates independent of material hardness or strength. The industrial application of ECM to residual casting material removal can potentially realize large cost savings and decreased component processing time by eliminating belt wear and increasing material removal rates. The approach taken in this work is the design and fabrication of a laboratory apparatus for the purpose of testing the ECM of casting material. Commercial ECM machines, while more powerful, can be excessively large and cost prohibitive when performing an initial feasibility study. Many times these commercial machines are calibrated to mass produce a specific part, and do not have the level of variability desired for laboratory experimentation. The test apparatus presented provides a robust and relatively low cost method of investigating the applicability of ECM to this purpose. The device is comprised of an electrolyte filtration and delivery system, a stable machining enclosure, and a single axis computer controlled tool. The ECM variables that can be adjusted include electrolyte temperature, mass flow rate, applied voltage, tool feed rate, and electrode gap. Process data from these variables is collected via multiple sensors in the machine and provides real-time feedback to users. A universal tool connection and workpiece fixture allows for different experimental setups to be easily tested. From experimentation with this test apparatus, it will be possible to identify optimum methods for the ECM of these residual casting artifacts.