| The surface quality of optical components is the key decision factors on optical system performance; only improving actual technology is difficult to solve the question. So people must research fresh machining theory and techniques method, explore fresh function of silicon wafers surface and energy, motion, instrument. Especially function and combination of fresh energy break through limit of machining equipments.The new phase of super smooth surface processing technology is that a series of methods and nonconductor polishing equipments. Nonconductor is a bran-new method including machining mechanism and machining method. The bran-new method indicates developing direction of super smooth surface processing. Hydrodynamic suspension super smooth surface processing is one of new technologies which are developed in allusion to super precision surface of burgeoning photoelectron component. Hydrodynamic suspension super smooth surface processing is a nanometer technique which is integrated of mechanical polishing, particle dynamics, fluid dynamics and chemistry.On the basis of dynamical fluid theory and principle of EEM(Elastic emission Machining), mechanism of hydrodynamic suspension super smooth surface processing is researched. It uses high velocity rotate tool that is nanometer and elastic to drive the nanometer suspension liquid, produces comprehensive functions as physics﹑chemistry﹑elastic emission and machine concussion in work piece surface, to attain nanometer surface quality. Fig 1 is sketch of machining principle. Machining mould is a polyurethane tool. Distance between outer surface of polyurethane tool and surface of work piece is 50um approximately. Polyurethane tool and work piece emerge in suspension liquid placed in a container. In order to achieve real-time control to the tool and work piece surface space and dynamic pressure in process, increasing the flexibility of hydrodynamic suspension machining system, we improved the polishing equipment. As shown in Fig 2 and Fig3.The improved system included piezoelectric multilayer,pressure sensor, support block Then we can achieve the data that dynamic pressure influence the processing impact.Hydrodynamic suspension polishing liquid is composed of nanometer particle,carried liquid and surfactant. Nanometer particle should have appropriate granularity and rigidity. If the rigidity is high, the efficiency is high. But the surface roughness value is big. If the rigidity is low, the surface roughness value is small. But the efficiency is low. The nanometer particle SiC whose rigidity is 9 has good stability,wearability and enduring high temperature. Water,kerosene and 18#lubricating oil are chosen as carried liquid which requires good hot stability,low volatility,wide difference in temperature. The effect of the surfactant are absorbing the nanometer particle surface,forming a cushion layer and avoiding to agglomerate for approaching between nanometer particles. The balance character of closed-water group and closed-oil group is the balance relation of closed-water group and apart-from-water group on strength. As the difference purpose of the surfactant, there is the proper proportion between closed-water group and apart-from-water group. PMAA-NH4 is chosen as the surfactant. It can pack the SiC and detach each other. This liquid has good fluidness,stability and disperse quality. It fits hydrodynamic suspension polishing machining.On atomic level, there is lots of atomic accumulation on the surface of work piece surface. The particles in the liquid that were Accelerated by dynamic pressure would Percussive the atomic accumulation. Then the atom would leave work piece surface. Finally we achieved super-smooth. As shown on Fig 4 and 5. Particles played a very important role in Hydrodynamic suspension machining progress. If the particles'energy is too small, they would not remove atom, and there would not be polishing action. So the particles'energy is very important. Because elastic hydrodynamic flow provided energy to the particles, so that it plays very important effect on machining progress.On the basis of studying the polishing theory, First we studied the factors to dynamic pressure of elastic hydrodynamic flow, the result was that machining gap and polishing tool have significant impact on the dynamic pressure. When the speed of polishing tool was 6000r/min and machining gap was about 10μm , dynamic pressure of polishing have maximum value. Second we designed experiment to certificate the theory on polishing K9 grass. The result is that the machining effect is increasing with increasing of dynamic pressure,with the decreasing of processing gap. But when dynamic pressure and processing gap Surpasses a definite value, the machining effect becomes worse. The polishing result is good when the polishing pressure is 5N and the processing gap is 10-20μm . The result just conforms to the theory. Fig 7,8 and 9 showed the data that processing gap and dynamic pressure influenced the machining effect.For all the experimental data, we can obtain the real-time control plan to polish K9 grass: the liquid density is 30g/L, processing gap is 10μm , motor speed is 6000r/min, slight adjustment the piezoelectricity folds piles and then the dynamic pressure changed to 5N, finally polishing 60 min. With this plan, we can obtain the polishing result Ra=3.14nm, which provides a basis to achieve compliance control of hydrodynamic suspension machining.Fig 10 and 11 show the polishing result under the real-time control plan to polish K9 grass.
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