Finishing of advanced ceramic balls for bearing applications by magnetic float polishing (MFP) involving fine polishing followed by chemo-mechanical polishing (CMP)

Scope and method of study. This investigation deals with the development of science and technology of finishing advanced ceramics, such as {dollar}rm Sisb3Nsb4{dollar} balls for bearing applications by magnetic float polishing (MFP) technology. Experimental design and analysis based on Taguchi method are applied to determine the optimum processing conditions for improving the surface quality in fine mechanical polishing by MFP technology. Polishing with various abrasives, different operating conditions, and polishing environments for {dollar}rm Sisb3Nsb4{dollar} bearing balls have been investigated. Fundamental mechanisms of chemo-mechanical polishing (CMP) have been studied based on thermodynamic and kinetic analysis.; Findings and conclusions. The methodology, involved mechanical polishing followed by CMP for finishing of {dollar}rm Sisb3Nsb4{dollar} balls from the as-received condition to a sphericity of 0.15 {dollar}mu{dollar}m and surface finish of Ra 4 nm by MFP technology has been developed. It takes about 20 hours to finish a batch of balls compared to a range of several weeks to several months by conventional grinding and polishing technology. High material removal rates (1 {dollar}mu{dollar}m/min) with minimal subsurface damage are possible by mechanical polishing with harder abrasives such as B{dollar}sb4{dollar}C or SiC in MFP. CeO{dollar}sb2{dollar} and ZrO{dollar}sb2{dollar} are found to be most effective abrasives followed by {dollar}rm Fesb2Osb3{dollar} and {dollar}rm Crsb2Osb3{dollar} for CMP of {dollar}rm Sisb3Nsb4.{dollar} CMP is found to be particularly effective in a water-based environment. There are similarities between polishing glass and polishing {dollar}rm Sisb3Nsb4{dollar} workmaterial including the role of water, polishing environment, and chemical effectiveness and mechanical hardness of abrasive for effective polishing.