Electrochemical micro-drilling of deep holes by rotational cathode tools

In numerous non-conventional micro-machining, electrochemical micro-machining has merits such as high removal rate, leaving no residual stress and lower roughness on surfaces of machined products. It has been considered as a highly promising technology in micro-machining. Little research has been done on the deep-hole micro-drilling by electrochemical methods. This work utilizes a rotational system to extract insoluble sludge from a deep hole and reduce the difficulty of filling deep hole with electrolyte. As well as a rotational tool cathode, a pulsed power generator is used to support the intermittence machining to increase the precision of the workpiece. The influence of working parameters, such as pulsed on-times, applied voltages, electrolyte concentrations, pulsed frequencies, tool feeding rates, tool diameters, tool rotational rates, and hole depth, on the hole overcut and conicity in a electrochemical micro-drilling is investigated. A high quality micro-hole with a 33.35-??m overcut is drilled by a tungsten carbide pin of diameter 50???m on a 304 stainless steel plate of thickness 1,000???m. The hole aspect ratio (depth/diameter) reaches 8.6. It shows that a rotational tool can be utilized in the deep-hole electrochemical micro-drilling.