Development of a machine tool for elid grinding

Abstract

Grinding techniques for mirror like surface generation of brittle and hard materials which are very difficult to machine have been improved in recent years by using super-abrasive wheels and precision grinding machines. In conventional grinding chip or particles get into the grinding wheel from the work piece and causes wheel glazing and loading which leads to rubbing of the work piece surface and subsurface damage. In Electrolytic In process Dressing (ELID) process, diamond grinding particles are bonded in cast iron wheels. During grinding, electrolysis is carried out to the wheel and a fine layer of cast iron drops off along with the machined debris and fresh diamond particles come in contact with the work piece and no wheel loading or glazing takes place. Thus damage free, clear surface is generated. Because there is no commercialized micro ELID grinding machine tool, this study is an attempt to design and develop an advanced, integrated and intelligent ELID grinding system for micro fabrication. Considering the cost and time of fabrication starting from scratch, we chose to upgrade a first generation Electric Discharge Machine (EDM) by making major modifications to the headstock, coolant supply system and spindle drive systems. Further modifications were made to achieve efficient and reliable monitoring of the in-process dressing of the grinding wheel, adaptive ELID power supply for optimal control of electrolysis and application of PC based open architecture motion controller.