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Efficient manufacture of dimensionally accurate optical surface on hard and brittle materials is a major concern for optoelectronic industry. Electrolytic in process dressing (ELID) grinding is proved as a reliable process to achieve this optical quality nano-surface finish on hard and brittle materials. Besides surface finish it is important to ensure dimensional accuracy by improving profile and form accuracy of the ground aspheric surface. Kinematic factors are commonly considered the reasons for the dimensional inaccuracy in a machined part. Software compensation is a direct and economical method to overcome several kinematic factors and improve the dimensional accuracy. Last, but most important, is the monitoring of achieved surface profile to ensure more accurate profile radius in the finished part. So an on-machine profile measurement system based on coordinate measuring machine (CMM) principle has been developed to check the profile radius of the ground surface. In this study software compensation was applied in ELID grinding of an aspheric surface in order to compensate the wheel wear until the measured surface profile machined on BK7 glass reaches within tolerable limit.

ELID grinding is drawing more and more attention by the researchers for its smart method of in-process dressing of the grinding wheel. A number of studies have been done by many people to investigate the mechanism and application of the process, though no significant effort has been made so far to develop an intelligent machinetool especially dedicated for ELID grinding. This paper aims to present the development and performance evaluation of an ultra precision intelligent ELID grinding machine. The machine is a five-axis machine, which includes three conventional linear axes (X, Y and Z) and a spindle axis. On top, another rotational axis has been included to assist the aspheric/spherical lens grinding. In order to introduce intelligence to the machine two on machine measuring system have been developed and incorporated. Experiments have been carried out on BK7 optical glass for evaluating the performance of the machine. A nano-level surface finish has been achieved, using #4000 series wheel.