Experimental investigations on the effect of relative particle sizes of abrasive and iron powder in polishing fluid composition for ball end MR finishing of copper

Demand for ultra-finished copper mirrors is very high in defence and laser optics industries due to their high heat conductivity and durability. In ultra-finishing, soft materials require gentle finishing for scratch free highest degree of surface quality. Ball end magnetorheological finishing is an advanced finishing process that confirms both the requirements of optical industries, i.e., finishing of complex surfaces and up to nanometre level of surface finish. In this study it is explored that the relative particle sizes of the abrasive and the ferromagnetic substance in magnetorheological fluid affect the chain structure and in turn the quality of the finished surface. The study has been carried out over magnetorheological polishing fluids composed of different sizes of iron particles and abrasives. The results show that magnetorheological polishing fluid having iron particles of 300 mesh size and alumina powder of 1,000 mesh size is most suitable combination for best surface finishing on copper samples.