Finishing of OFHC copper using fluid filled open-cell porous flexible abrasive impregnated tools

Abstract

Super finishing of oxygen-free high thermal conductivity (OFHC) copper disks is of great interest as copper is widely used material for high power rated mirrors in laser and other optical systems. It is difficult to super finish copper using traditional finishing processes as it is soft and can be scratched easily. Flexible tools that conform to component shape and maintain low as well as uniform pressure are needed for finishing of soft materials. In this work, open-cell porous flexible abrasive tools are developed using solvent casting method with polyurethane as the base polymer and SiC particles as abrasives. The open-cell porous tools are saturated with deionized water before use. The tools are self-replenishing as the abrasives are uniformly dispersed in the tool and the fluid trapped in pores acts as coolant as well as lubricant. The viscoelastic behavior of the fabricated tools with different abrasive concentrations is characterized using a dynamic mechanical analyzer (DMA). Spot finishing experiments are carried out to optimize the tool RPM, tool compression, and abrasive concentration for better surface finish. The average areal surface roughness (Sa) of copper disk reduced to 54 nm from 946 nm.