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Ultrasonic vibration polishing (UVP) which integrates mechanical polishing and ultrasonic vibration technologies is applied to process monocrystalline silicon. The predictive model for material removal rate (MRR) is developed which includes the microscopic contact among the workpiece, abrasive grains, and polishing pad, the scratch effect of embedded abrasive grains, and the impact removal of free abrasive grain on the workpiece surface. This model unveils the reasons for the enhancement of MRR and the effect of different parameters on MRR during UVP. UVP experiments of monocrystalline silicon were carried out to validate this model. It is found that the MRR model is in excellent consistency with the measured MRR and the error rates could be controlled to less than 10%. The increase in spindle speed and ultrasonic amplitude increases the kinetic energy of the abrasive grains. The increase in abrasive grain size improves the contact area between the abrasive grains and the workpiece. Therefore, these contribute to the MRR of the UVP. In addition, different polishing parameters (spindle speed, ultrasonic amplitude, and abrasive grain size) were analyzed and compared on the surface roughness and microscopic local morphology. This work not only offers a novel method for predicting the machining efficiency of UVP but also provides an excellent reference for the evolution of ultrasonic vibration-assisted technologies. [ABSTRACT FROM AUTHOR]

BK7 glass is widely used in various optical instruments as a common ceramic material. However, there are still several difficulties in the polishing process due to its material properties. Ultrasonic vibration–assisted polishing (UVAP) is used widely for its excellent material removal properties. However, there are few researches on the model of UVAP material removal for tilted. Therefore, this paper investigates this problem. A model of UVAP material removal was established for titled column polishing; The pressure distribution and velocity distribution in the contact zone were modeled by means of experiments and geometric analysis. A series of orthogonal experiments were conducted, and the experimental results showed that the coefficient of determination was above 0.9 after fitting the actual profile to the predicted profile. The results of the orthogonal experiments were also analyzed by ANOVA. The predict error of maximum removal depth was less than 13.12%. The error of material removal rate (MRR) was less than 9.24%. By power spectral density (PSD) analysis, it was found that the introduction of ultrasonic amplitude has a good effect on suppressing the medium and high-frequency errors on the machined surface. The novel model can be used to optimize machining parameters and provide theoretical support for complex parts polishing. [ABSTRACT FROM AUTHOR]

K9 optical glass is one of the typical components in optical systems. However, because of its poor fracture resistance, it is difficult to polish it with ultra-precision and high-efficiency and without any surface damage simultaneously. The emergence of the obliquely axial ultrasonic vibration-assisted polishing (UVAP) method can solve this problem which encounters in polishing efficiency and shape accuracy. However, due to the unclear material removal profile (MRP) mechanism, obliquely axial UVAP is not widely used in the processing field. This paper introduces the obliquely axial UVAP method in research processes, mainly focusing on the fixed point MRP analysis of the obliquely axial UVAP. Based on Hertz's contact theory, polishing pressure, the length of the semi-long axis (LLA) and the length of the semi-short axis (LSA) of the contact area are calculated under ultrasonic vibration conditions. Meanwhile, the relative linear velocity distribution of the oblique polishing tool in the instantaneous contact area is modeled by mathematical geometry method. A novel model of the MRP distribution for obliquely axial UVAP is proposed following the Preston equation. Subsequently, a series of polishing experiments were carried out to verify this model. The results show that the numerical model has good agreement with the experimental results on MRP, LLA, LSA, material removal depth and material removal rate (MRR). In addition, the material removal capability can be significantly improved by larger ultrasonic amplitude and larger oblique angle. This model not only more clearly elucidates the processing mechanism of obliquely axial UVAP, but also provides theoretical support for the polishing of free-form optical lenses. [ABSTRACT FROM AUTHOR]

• Preston coefficient is affected by ultrasonic amplitude • Contact pressure is affected by ultrasonic amplitude • Large ultrasonic amplitude helps to improve the polishing ability • Local surface profile can be well predicted by the proposed calculation model • Prediction of surface profile is a basis for free-form surface polishing of UVAP With the rapid progress of science and technology, many applications of hard and brittle materials require advanced and suitable machining-techniques. One technique in particular, ultrasonic vibration-assisted polishing (UVAP), has been studied intensively by researchers worldwide. These studies indicate that UVAP has the capability to improve the surface quality as well as the machining efficiency. However, few studies focus on the deterministic material-removal of UVAP. The difference between generated and theoretical surface profiles determines the surface accuracy. Therefore, this paper focuses on predicting the generated local surface profile and providing a theoretical basis to reduce this error by controlling the polishing parameters. In addition to the axial ultrasonic vibration of polishing tool, ultrasonic atomization was adopted to provide uniformly distributed polishing slurry. To ensure sufficient surface-accuracy, it is necessary to predict the generated surface profile for a fixed spot as a basis research. This means, to enable accurate predictions the following improvements are realized: (i) A novel model for the elastic spherical contact-deformation of the polishing tool is used to calculate both the polishing force and contact radius. It takes into account the nonlinear elasticity of the polishing tool and the lateral extension of the contact area, which makes it more consistent with the actual deformation. (ii) A novel model for the material-removal distribution function for UVAP is proposed, based on the Preston equation. It considers the periodic changes of polishing force and contact radius caused by ultrasonic vibration. (iii) A series of fixed-spot polishing experiments on BK7 glass are carried out to verify the proposed models. The results show that the Preston coefficient is affected by axial ultrasonic amplitude, and large ultrasonic amplitude improves the polishing ability. In addition, the generated local surface profile, the maximum contact radius, as well as the material-removal depth and material-removal rate (MRR) can be predicted well. The new models not only provide a possibility to realize deterministic material removal but also enables in-depth-understanding of UVAP. It also represents a basic theoretical foundation for future, flat or free-form surface-polishing. [ABSTRACT FROM AUTHOR]

Ultrasonic polishing (UP), as an efficient and clean precision machining process, is increasingly applied in the hard and brittle material processing. To minimize the surface damage and polishing expenses, this paper aims to prepare novel graphene oxide/diamond hybrid slurries (GDS) by ultrasonication, and to investigate the UP mechanisms for silicon carbide (SiC) ceramics on UP and tribological experiments. Findings showed that GDS exhibited superior polishing performance compared to diamond polishing slurries. Moreover, the promotion effect of GDS was more obvious under UP. The surface roughness was improved by 31.62% after UP using GDS with a graphene oxide (GO) content of 0.1 wt%. On the one hand, the lubrication of GO reduce the wear and coefficient of friction. On the other hand, ultrasonic vibration induces stronger impact kinetic energy of abrasives to remove material and allows for a better uniform distribution of GDS to further enhance the lubrication characteristics of GO nanosheets. The application of GO in UP is a processing technology penetrating the manufacturing industry and even human life, laying the foundation for SiC nano-polishing. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration polishing (UVP) is an important method for the precision processing of optical glass, which is good for improving surface quality and processing efficiency. So far, the material removal mechanism in UVP is not well understood and the various process parameters involved are not considered. To achieve ultra-precision polishing under optical glass, this paper carries out the axial UVP method. The material removal profile (MRP) is critical to affect the surface accuracy. A new MRP is developed for UVP based on the Urick attenuation model and the proposed material removal coefficient distribution function, considering the dynamic pressure changes under ultrasonic vibration, the attenuation effect of the acoustic pressure propagation process and the inhomogeneous distribution of the abrasive particles in the contact area during the ultrasonic electro-spindle rotation. Through a series of polishing experiments and simulations, the results show that the maximum errors of the actual material removal depth (MRD) and the actual material removal rate (MRR) from the model simulation results are 8.54% and 9.92%, respectively. The accuracy of the model is further demonstrated by the Pearson correlation coefficient. When the amplitude of UVP is 9 µm, Sa and Ra are 60 nm and 68 nm, which are reduced by 37.50% and 22.73%, respectively, compared with conventional polishing. This research can contribute to the deterministic processing of UVP, and provide a theoretical basis for the application of optical glass. [ABSTRACT FROM AUTHOR]

K9 optical glass has an important position in the field of optical material because of its excellent chemical stability and optical projection. The hard and brittle characteristics of K9 optical glass make conventional processing difficult and time-consuming. A non-conventional hybrid polishing system combining ultrasonic atomization (UA) spraying method and axial ultrasonic vibration was developed for processing K9 optical glass. This system utilizes the high-frequency vibration characteristics of ultrasonic vibration technology: On the one hand, the ultrasonic atomization spraying method is used to generate evenly distributed atomized droplets for polishing, on the other hand, the axial ultrasonic vibration of the polishing tool provides impact kinetic energy for the free abrasive particles. Mechanical polishing (MP), ultrasonic-assisted polishing (UVP), mechanical polishing under ultrasonic atomization spraying (UA-MP) and ultrasonic vibration polishing under ultrasonic atomization spraying (UA-UVP) were carried out on K9 optical glass. The material removal rate (MRR), material removal depth (MRD), surface quality and surface micromorphology of the polished workpieces were also analyzed and compared. The experimental results showed that the best surface was obtained at UA-UVP (A Ⅰ = 9 μm) with MRR of 0.0994 mm3/min, material removal depth of 26.816 μm, the Ra and Sa values were 0.028 μm and 0.033 μm respectively. Meanwhile, no obvious pits and scratches were observed on the micromorphological surface. Ultrasonic atomization contributes to even material removal from the polished surface and axial ultrasonic vibration of the polishing tool has a significant effect in improving the polishing characteristics, which provides the experimental basis for applying ultrasonic vibration technology in polishing. [ABSTRACT FROM AUTHOR]

• A model of material removal for axial ultrasonic assisted polishing of spherical polishing heads was developed. • The mechanism of trajectory generation for polishing tools in quadratic cylinder surfaces was presented. • An innovative ultrasonic assisted surface morphology prediction model was established based on material removal models and surface trajectories. • Two dimensional power spectral density and roughness analyses were performed on the experimental results. Aluminum alloys with light weight and excellent performance in processing are widely used in different kinds of optical reflector elements. In this paper, An innovative model for predicting the surface morphology of ultrasonic assisted polishing quadratic cylinder surfaces was developed based on the material removal model and calculation of the trajectory methods. Experimental verification was accomplished. By analyzing the simulation and experimental surface roughness analysis and two-dimensional power spectral density, the maximum error between the roughness experiment and the simulation is 9.3%, and the maximum error between the peak two dimensional power spectral density of experimental and simulation results is 9.8%. Surface properties can be enhanced and errors of medium and high frequency in the polished surface region can be diminished with the ultrasonic assisted polishing. This study provides important guidance for ultrasonic assisted polishing of different types of quadratic cylinder surfaces including without limitation cylindrical, elliptic, and parabolic surfaces. [ABSTRACT FROM AUTHOR]

• Material removal models for spherical polishing tool in axial ultrasound-assisted polishing was developed. • Predictions of dynamic contacts for polishing processes were made. • Pressure and velocity distribution in the multi-position contact area were accounted for. • Extreme deviations and gray correlation analyses for taguchi experiment were undertaken. Ultrasonic-assisted polishing methods are widely used for the precision processing of hard and brittle materials such as glass and ceramics due to their excellent polishing performance. Most research has been focused on basic removal mechanisms of ultrasonic-assisted polished materials. Some investigators have studied the profile of surfaces after conventional mechanical polishing, but less research has been done on the profile of faces after axial ultrasonically assisted polishing. This paper has established a novel force prediction model for the ultrasonically assisted polishing, which is critical for geometrical accuracy and surface finish. Also a material removal model has been developed for this process using a spherical polishing head at different tilt angles. Pressure and velocity distributions have been calculated for multi-position contact areas. The experimental study of multiple trajectory polishing of alumina ceramics showed a good correlation between the experimental and simulated surface profiles. The ultrasonic polishing process parameters were optimized by applying the gray correlation analysis. The obtained results can be used not only select ultrasonic assisted polishing process parameters but also provide theoretical underpinning for surface polishing trajectory planning. [Display omitted] [ABSTRACT FROM AUTHOR]