Effects of Lapping Parameters and Slurry Type on Machining Performance of Sapphire Fairings with Controllable Texture Diamond Tools

Three diamond film tools with controllable texture were fabricated prepared by chemicalvapor deposition (CVD) method. Their surface quality was analysed, and the tools were innovatively used to lap sapphire fairing. The effects of the lapping pressure, type of the lapping fluid and tool, and lapping time on the roughness and material removal rate of the sapphire fairing were investigated. The surface morphology and quality of the tool were analysed by SEM and XPS to explain the reason why ethylenediamine was used as the lapping fluid with the highest removal rate. The lapped sapphire fairing surfaces were analysed. The results showed that the surfaces were relatively smooth and bright, with only a few scratches. The removal rate of this processing method reached up to 38.6µ m/min. The surface roughness of the sapphire fairing after machining was 0.25 − 0.6µ m. The spherical error of the ball surface measured by the three-coordinate was 1.616µ m. The proposed high-quality machining method is efficient for lapping sapphire fairing. It provides a process reference for spherical and curvedsurface machining of similar crystalline materials.