Abstract: A viscoplastic cluster MR effect pad is formed between the surface of polishing plate and the workpiece. Under the effect of a magnetic field, MR effect pad remove material from the surface being machined, which has been applied to polish a large variety of brittle materials, ranging from optical glasses to hard crystals, to a nanometer surface. Knowledge of forces acting is important to understand the mechanism of material removal for MR effect pad. Three-component dynamometer instrumentation is used to on-line record the normal force and tangential force acting on the workpiece through the MR effect pad. It is found that the maximal tangential force Ft value is 32.25 N and the maximal normal force Fn value is 62.35 N, and the ratio between them is about 0.46-0.77. The most contribution is observed that of the machining gap and magnetic field strength on the forces developed on the workpiece surface, followed by CIPs and abrasives concentration, the fluid flow rate, the polishing plate speed, while the least contribution is noticed by the feed distance and feed rate of workpiece. The forces from the cluster MR effect pad and the ratio Ft/Fn increase with the increase in the hardness of the workpieces. The forces acting on the harder workpieces have the characteristic with low normal pressure and high shear force, and this is beneficial to improve the quality of super-smooth planarization polishing.

Key words: machining parameters, MR effect pad, normal force, tangential force