Development of low cost ball end magnetorheological finishing process

Abstract

A finishing process for nanofinishing of workpiece surfaces using a low cost ball end MR finishing tool is developed. It is used to finish both ferromagnetic and non-ferromagnetic using ‘smart’ fluid name as magnetorheological polishing (MRP) fluid. It is mainly constituted of base fluid, carbonyl iron particles and abrasive particles. The existing ball end magnetorheological finishing process is able to finish 3D complex shapes but comparatively as likely to higher initial setup cost. The uniformity in magnetic field produced by the earlier ball end finishing process was less at the tool tip surface due to central hole in rotating core. In the presently developed a low cost ball end MR finishing process produce a more uniformity in the magnetic field at the tool tip surface due to without any central hole in rotating core. The finite element analysis of the present developed low cost ball end magnetorheological finishing tool was done in MAXWELL ANSOFT V13 (student version) to analysis the magnetic flux density distribution at the tool tip surface. The electromagnet modelling of ball end magnetorheological finishing tool was done for both core with central hole and core without central hole. The magnetostatic finite element analysis with workpiece was done on ferromagnetic to observe the magnetic flux density at the tip of ball end magnetorheological finishing tool. The CAD modelling of C-shape bracket and the present ball end magnetorheological finishing tool have been carried out in CREO elements/PROE. A low cost ball end ball end magnetorheological finishing tool has been made up and attached to the developed set up. A PLC controlled experimental setup is developed with the aim of study the process description and performance during precise finishing of the workpiece surfaces. The experimentation was carried out on mild steel workpiece in order to find the effect of finishing time on the change in the value of surface roughness. The initial average surface roughness value was measured as 440 nm using surftest. Scanning electronic microscope (SEM) analysis was carried out before/after finishing in order to determine the surface morphology of the workpiece. The results concluded that the average surface roughness value decreases to 20 nm from initial surface roughness value 440 nm in 90 minutes of finishing time in the present developed finishing setup. The presently developed low cost ball end magnetorheological finishing set up was found comparatively more finishing capability in terms of finishing time and more uniformity of magnetic field at the tip surface of the tool.