Studies On The Key Technologies In Ultra-precision Machining Of Hard And Brittle Materials

The studies on the key technologies in ultra-precision machining of hard and brittle materials were carried out by using Logitech PM5 precision lapping & polishing machine, represented by LBO crystal. Our researches obtain the high-precision of each surface quality characteristic, decrease the dependence of ultra-precision machining of crystal materials on operator's experience and accelerate the industrialization of ultra-precision machining of hard and brittle materials.Chemical mechanical polishing (CMP) is one of the most important technologies of ultra-precision machining. Firstly, we investigated the mechanism of material removal and formation of super smooth surface in CMP. And the material removal mechanism of CMP at atomic level was described. The comprehension and hypothesis of material removal mechanism of super smooth surface polishing were enunciated. For instance, we circumstantiated material removal mechanism and formation of super smooth surface in CMP of LBO crystal. Each input variable which affects each surface quality characteristic in CMP was theoretically analyzed.Secondly, each input variable which affects each surface quality characteristic in ultra-precision machining process of LBO crystal was experimentally described in detail. Especially in CMP, the experimental researches involved that input variables, polishing abrasive, polishing pad, pressure and velocity etc., act on the surface quality characteristics, surface roughness, surface flatness and material removal rate, respectively. According to this study, the technologic processes of ultra-precision machining of LBO crystal are comprehensively optimized and stabilized. LBO crystal of surface flatness <λ/10, surface roughness < 0.2 nm RMS and very few micro scratches or damages is obtained.According to the technologic processes of ultra-precision machining of LBO crystal, we manufactured the other hard and brittle materials, such as transparent Nd:YAG ceramics, K9 glass, KTP crystal and so on. And the high-precision surface quality of the sample is obtained. The extension of the technologic processes of ultra-precision machining is successfully achieved, which established the groundwork for future industrialization of ultra-precision machining of hard and brittle materials.