Experimental Feasibility Study of Tunable-Stiffness Polishing Wheel via Integration of Magneto-Rheological Elastomers

摘要

The mechanical polishing is one of the critical microfabrication processes in semiconductor and a host of other critical industries. There has been a great effort in consumable development (pads, slurries, etc.) to improve the overall polishing efficiency and resulting surface quality. In this study, we explored a unique composite polishing wheel with integration of magnetorheological elastomers (MREs). The proposed design aims to control local contact area and contact pressure during fine polishing process and thereby control the material removal rate with precise adjustment of the magnetic field. Two (Two MRE microstructure) MRE, isotropic and chain structured orthotropic, materials were included in the design. The feasibility of the designed wheel and the workpiece-wheel contact characteristics were tested under compression loading. An experimental setup was designed to apply vertical and horizontal magnetic fields. Digital image correlation technique was utilized to measure the local in-plane strain field around contact region. It was found that addition of MRE inserts can alter the local stress field around the contact area, resulting in a strong modulation with up to three-fold increase of both the contact area and the local pressure distribution. Finite element analysis highlighted the intricate role of the MRE inserts in modulating the local strain field around the contact area, and thereby inducing a concurrent increase in both the contact area and the local pressure distribution under the same nominal macroscopic applied load. The observed demand modulation of the contact pressure is anticipated to have a marked effect on the polishing process and the resulting surface quality.