Tools for Electrical-Discharge Hole Drilling

Multi-electrode electrical-discharge drilling of holes and grooves is widely used in aerospace manufacturing. We herein consider the problem of tooling the operations of simultaneous electrical-discharge drilling of multiple small-diameter holes in filter-type parts. Given the required area of the nominal bore and the required dimensions, we designed a filter with rhombus-shaped holes with an external diameter of 0.25 mm and apical angles of 65,030′ and 114,030′. New designs for electrode tools are proposed and the process of making and using those is described. Assembling a multi-electrode tool for the part took 330 min. Using standard 300 mm rods was enough to make 218 filters with this tool. Technical and economic calculations show that using multi-electrode setups depends on the annual production of the same part. For each specific product, one can calculate the critical annual production value, which is necessary for such multi-tool setups to be cost-effective.