Electrolytic Dressing of Bronze-Bondel Grinding Wheels in Fixed-Load Grinding

Abstract

When using bronze-bonded diamond grinding wheels, no methods of intermittent or in-process dressing have been automated to the point where sharp, continuous cutting performance can be obtained over the life of the grinding wheel when grinding hard ceramics. ELID may provide the first such continuous-dressing technique for ceramic grinding with metal-bonded wheels. With ELID, the wheel is made the anode in an electrolytic cell - a system of two electrodes and an electrolyte undergoing an electrochemical process as the result of an electric potential applied across the electrodes (note the distinction from an electrochemical cell, which generates an electrical potential in response to spontaneous electrochemical reactions between electrodes and electrolyte). The grinding coolant serves as an electrolyte, and a graphite cathode completes the cell. An applied voltage across the electrodes causes the anodic wheel bond to be continuously eroded, exposing sharp, new diamond grains before the already exposed diamonds become unacceptably dull. The graphite cathode evolves hydrogen gas, and neither gains nor loses material in the process. All of the ELID systems described to date use cast iron for cast iron fiber bonded grinding wheels, though such wheels are not common in the US [1]. Experiments have been performed at Boston University using two load-controlled grinding machines. Currently, experiments are also underway on an ultraprecision infeed-controlled grinding machine, with both iron and bronze wheels. The process dynamics for bronze are found to be markedly different than that for iron wheels. The results show significant promise for this technique in ceramic grinding with bronze-bonded wheels.