Papers by Keyword: Ultra-Precision Polishing

Abstract: Sapphire (Al₂O₃ crystal) is a hard and inert material with good mechanical, optical, physical and chemical properties that plays important roles in optics and electronics. The surface quality is the key element of sapphire components especially in optical field. This paper mainly introduces four methods of ultra-precision polishing, researches based on polishing theories and slurry. It can be a conclusion that traditional polishing methods can improve material removal rate assisted by ultrasonic.

Abstract: The Quartz substrates are widely used in various fields, and the requirement for the surface quality of quartz substrate is higher than ever before. This paper focuses on the ultra-precision polishing technology for the quartz substrates, and the material removal mechanism in the process of ultra-precision polishing is discussed. The results showed that an extremely smooth surface of quartz substrate was obtained in the ultra-precision polishing process, and the best surface roughness reached Ra 0.82nm. Meanwhile, the thickness can be controlled very well.

Abstract: In this paper stable eccentric immersed polishing is investigated according to Preston equation. The polishing trace, speed, density of polishing fluid etc were analyzed in detail. The polishing practicability of the technology was verified for polishing a piece of zerodur and the supersmooth surface with the flatness of PV0.04μm was obtained. The roughness of the surface has decreased to Ra0.37nm from initial Ra1.5nm after polishing 120 minutes.

Abstract: Ultra-precision polishing is an emerging technology for producing superfinishing surfaces with sub-micrometer form accuracy and surface finish in nanometer range. It has been applied in superpolishing the freeform bearing surfaces of orthopaedic implants. It is believe that the superfinished surfaces are capable of prolonging the life of the implants. In this paper, an experimental investigation of ultra-precision polishing of orthopaedic implants and the study of the wear characteristics of the superfinished surfaces using a multi-directional pin-on-plate wear test simulator are implemented. Tests were carried out over 3 million cycles using Zeeko IRP200 superfinished cobalt chrome pins articulating against cross-linked UHMWPE plates. The results were compared to that of manually polished pins articulated against the same UHMWPE material. The results show that the Zeeko IRP200 polished pins produced better wear performance that that of the manually polished pins.

Abstract: The ultraviolet irradiation-assisted ultra precision polishing was performed on single crystal diamond substrates. This polishing method has been newly developed in our laboratory. The change of polishing performances was investigated by the presence of the UV irradiation. The polished surfaces were evaluated by the observation with WYKO. The experimental results are as follows; Surface roughness of diamond substrates polished under UV irradiation has become clearly smoother than that without UV irradiation. The surface roughness by this polishing method was reached to be 0.19 nm Ra on (100) surface of single crystal diamond. The equivalent surface was obtained on (110) surface by the UV-polishing.

Abstract: The high precision balls are requested in national defense, astronautics and high-tech commercial domain urgently. Conventional precision machining methods are sensitive to uniformity of abrasives and machining environment. After precision machining, there are easily to produce thick damaged layer on the ball surface because of machining stress and chemical conversion. On the basis of the floating polishing mechanism, a new scatheless ultra-precision polishing method of ball surface can solve the problems of abrasives uniformity effectively and damaged layer. In order to ensure that the new polishing method polishes ball surface equally, the appropriate angular velocities of the ball should be selected. This paper sets up the mathematical model about the motion of ball. By analyzing and simulating the relationship of the angular velocities, the best processing parameters are acquired.

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.