Research On Non-water-based MR Finishing Fluids And Process Of Magnetorheological Polishing

With the rapid development of aerospace, defense industry, information and microelectronic technology, the processing of super smooth optical components has been more and more concerned. The processing of optical crystal materials that soluble in water is extremely difficult, such as processing the KDP crystal that can be used in intense laser optical system. Magnetorheological polishing technology is an important method for processing super smooth optical part. Magnetorheological polishing technology that use water-based magnetorheological fluid as processing media can not be used to processing stable optical crystal materials. This paper studies a kind of non-water-based magnetic fluids that can use to processing water-soluble crystal materials.Making non-water-based Magnetorheological (MR) finishing fluids has been research in this paper. First of all, polyethylene glycol (peg) and two silicone fluid were used to base fluid on concern the performance and economical comparison of non-water-based load fluids. Secondly, the volume ratio of non-water-based magnetic fluids is 5% carbonyl iron powder, 2.5% silicone oil,42.5% no water ethanol and 50% polyethylene glycol (peg) in reference to common water-based magnetorheological fluid. After the performance test of viscosity and retrogradation, it was proved that the polyethylene glycol (peg) load base magnetorheological fluid has better properties. The result from the Magnetorheological polishing removal efficiency test suggests that the polyethylene glycol load base magnetic fluids are available for finishing polishing of optical components. At last, we carry out K9 diameter 300mm optical components processing research by using this magnetorheological fluid. We carry out orthogonal tests to investgate the influences of Material removal amount and surface roughness with different process parameters (the main process parameters:magnetic field control voltage, the polishing head-work piece gap, work- piece axis swing frequency, work-piece axis rotation frequency, the rotation frequency ofring polishing head), draw their curvilinear relation chart, reveal the law between them. and finally obtained the optimal parameters.After the magnetorheological polishing,the final surface roughness kf K9 glass work-pieces, which has a initial roughness of 60mm grinded by the W7dianond powder, were obtained at the best value of 0.73nm. This indicated that the magnetorheological fluid is available in large-diameter planar optical components. Process experiment verifies polyethylene glycol (peg) the magnetorheological polishing that can use to machining optical crystal materials that soluble in water. Finally, we come to a non aqueous magnetorheological polishing fluid ingredient (volume ratio):5% carbonyl iron powder; 2.5% silicone oil; 40% ethanol;50% polyethylene glycol; 2.5% additive.When doing the process experiment with large diameter optical components on the band type magnetorheological polishing function test prototype, it will appear the problems of bad heat dissipation for long time polishing and the weakness of easy jitter for the the swinging arm high speed rotation, which result in bad final finishing quality. Those disadvantages has been improved in the new the band type magnetorheological polishing engineering prototype, by the way of welding water circulation structure on polishing head to improve the heat dissipation and through the use of spring damping method to improve the weakness of easy jitter for high speed rotation of the swinging arm.