Papers by Author: B.C. Tao

Abstract: To understand the mechanism involved in the lapping process of the silicon nitride balls, the wear mode is investigated in this paper. The abrasion tests were performed on a ball-plate wear test apparatus with different loads (0~2N/ball) and slurry concentrations (5%wt~30%wt W20 B4C3). The abraded surface is observed by optical telescope. A wear-mode map, which defines the regimes for two-body abrasion or three-body abrasion dominating in the micro-scale abrasion test, is plotted with two axes: load and concentration of abrasive. An empirical formula for the wear mode transition is adopted to calculate the transition point S*, which can then used to predict the wear mode in lapping process of silicon nitride ball.

Abstract: A novel lapping mode is developed on the base of present eccentric v-grooves lapping mode for precise balls. The kinematics analysis shows that the ball spin axis can wiggle up to 180° under the developed mode, so the lapping trace will be dispersed onto the whole surface of the ball. The effect of offsetting and groove radius on the lapping uniformity in the developed eccentric v-grooves, the present eccentric v-grooves and the traditional v-grooves lapping mode are compared, and the advantage of the developed mode is that the impact offsetting is less while the groove radius has no impact.

Abstract: STAVAX ESR（S-136）is a type of high stainless steel, used in precision mould widely . It has fine anticorrosion, polishing-alike, wearable，good process capacity and quench stability. To obtain the smooth surface of STAVAX ESR, the material removal mechanism in the paper is discussed. The experiment is processed on the ultra-precision plane polishing machine (Nanopoli-100). The experiment processes are as follows. Rough lapping and Ultra-precision lapping: the material of lapping pads is cast iron. #1000Al203 (10wt%) abrasive powders are used in rough lapping. Finally, surface roughness is 62nm. In ultra-precision lapping, abrasive powders are for #4000Al203（10wt%）. Removal rate is 1nm with linear velocity 8.6m/min, pressure 3.65MPa. After 4000 rounds, surface roughness is 35nm.Ultra precision polishing: The super smooth surfaces of STAVAX ESR（S-136）with 5nm roughness have been obtained by adopting SiO2(> 30wt%) slurry and soft tin polisher in the experiment.