Nanofinishing of a typical 3D ferromagnetic workpiece using ball end magnetorheological finishing process

A nanofinishing process using ball end magnetorheological (MR) finishing tool was developed for finishing 3D workpiece surfaces. In this process a ball end shape of MR polishing fluid is generated at the tip surface of the rotating tool which is used as a finishing spot. This paper is focused on surface finishing and performance evaluation of a typical three-dimensional ferromagnetic workpiece using a ball end magnetorheological finishing process. A typical 3D workpiece surfaces were made by milling process at different angles of projection such as flat, 30°, 45° and curve surfaces. The experiments were performed on these typical workpiece surfaces by ball end MR finishing setup to study the effect of number of finishing passes on final surface roughness. The experiments were also performed on a flat ground surface to study the process performance as compared with the milled workpiece surfaces. The finite element analysis has been done to study the distribution of magnetic flux density at tip surface of the tool with an inserted typical 3D workpiece surfaces. When these typical workpiece surfaces were finished by proposed MR finishing process, the surface roughness were reduced as low as 16.6 nm, 30.4 nm, 71 nm and 123.7 nm respectively on flat, 30°, 45° and curve surfaces for 60 passes of finishing. The roughness of flat ground surface was reduced as low as 19.7 nm for 120 min of finishing. The experimental results demonstrated that the newly developed ball end magnetorheological finishing process was effective in finishing typical 3D ferromagnetic workpiece surfaces.

► Modified ball end MR finishing process was used for finishing of the typical 3D surfaces.
► Process capability was demonstrated on 3D milled surfaces and flat ground surface.
► Variation in magnetic normal forces and flux density zones were found by finite element analysis.
► Effects of finishing forces were observed on final surface roughness of 3D typical surfaces.
► Variation in normal forces can be minimized by providing a tilting motion to MR finishing tool.