Electrochemical Hole Making

Abstract

The surface integrity of the side walls of holes is a critical factor in applications involving fatigue and/or corrosion. In the conventional ECM hole making, the tool consists of a copper (brass or steel) pipe insulated on the outside and having a thin conductive tip. This tooling design affects the surface integrity of the holes produced. The relative rough surface finish on the side wall is a result of the low current density on the side gap caused by the insulation of the tool. Furthermore, the reliability of the process is reduced due to delamination and pinholing of the tool's insulating layer. In order to overcome these shortcomings, an electrochemical hole making technique was developed, which uses uninsulated tools and NaC10, electrolyte. This technique was used to produce a large number of small holes in stainless steel plates. This method shows advantages over other hole making techniques in terms of the resulting surface quality and the process reliability. A model for side wall machining is presented and compared to the experimental results.