Kinetic Modeling and Material Removal Mechanism Analysis of Fixed-Abrasive Polishing for Lithium Tantalite Wafer

Abstract

As a typical multi-functional soft-brittle material, lithium tantalate (LT) exhibits excellent electro-optical and ferroelectric properties and now has been widely applied in many fields, such as electro-optical modulators, pyroelectric detectors, and surface acoustic wave substrates. Traditional free-abrasive polishing processing of lithium tantalite crystals is generally fraught with poor efficiency for its lower fracture toughness. This study proposed a method of polishing lithium tantalite wafer by means of fixed-abrasive plates. A cutting force model and the relative cutting speed model of the machining mechanism of fixed-abrasive plates were first established, and then the main influencing factors of cutting force and relative cutting speed were analyzed on the basis of the theoretical model. It was found that cutting force is influenced by eccentricity and load, while relative cutting speed is influenced by eccentricity and the fixed-abrasive plates’ rotation speed. Finally, single-factor tests were conducted on these influencing factors, and the comparative analysis between the experimental results and those in the theoretical model shows that they are highly correlated to each other. After 30 min of polishing under the optimized parameters w = 60 rpm, e = 90 mmand applied with variable load, the surface roughness S a of the workpiece can be reduced to 1.234 nm, and the MRR reaches 14.821 μm/h.