INVESTIGATIONS ON THE SURFACE-ROUGHNESS PRODUCED BY BALL BURNISHING

Burnishing, a plastic deformation process, can be used to finish surfaces. Experimental work was conducted on a vertical machining centre to establish the effects of various ball burnishing parameters: depth of penetration, feed, ball material, burnishing speed and lubricant, on the surface roughness of AISI 1045 specimens. The ball materials used were WC and SUJ2. It was found that all the parameters studied affect the surface finish to varying degrees. The surface roughness parameter R(tm) first decreases and then increases with increasing depth of penetration. The effects of feed and burnishing forces on the surface finish also showed similar trends. The effect of speed depends on the type of lubricant used. Grease is a better lubricant than cutting oil for the speed range of 450 mm min-1 to 1200 mm min-1. With appropriate selection of the process parameters, a pre-machined surface roughness of about 4-mu-m can be finished to approximately 0.7-mu-m.