Ultrasonic Polishing Research Articles

Design and Experimental Research of Atomizer Based on Micro Abrasive Ultrasonic Polishing

The ultrasonic vibrator (atomizer) will play an important role in micro abrasive vapor mist ultrasonic polishing process. In this article, three methods are used to design the atomizer, and the effect of atomization is verified by experiment. The mesh atomizer has the best effect of atomization. Study on the ultrasonic mist, the mist formed by ultrasonic atomization of the slurry containing micro abrasive has a erosive force, which can be used for polishing the workpiece surface. Polishing is performed by means of a mist stream formed by ultrasonic vibration with a slurry containing a micro abrasive. Specifically, the ultrasonic vibration is used to atomize the slurry containing the micro abrasive to form a vapor mist. Then, polishing is performed with a mist containing micro abrasive.

Wear Characteristics of Metallic Counterparts under Elliptical-Locus Ultrasonic Vibration

Wear behavior is influential to improve friction drive and wear lifespan of actuators or motors, which work at an elliptical locus vibration. Sliding wear tests of metallic friction pairs are conducted by a laboratory rig of ultrasonic vibration. Surfaces of the different metallic sliders are characterized using surface roughness, Abbott curves and fractal dimension. Results show that surface roughness is reduced to varying degrees in the metallic sliders due to ultrasonic polishing and/or micro-rolling effect. Variations in the fractal dimensions of contact surfaces are consistent with that of surface roughness. Wear traces demonstrate that plastic deformation and cracking are the primary failure modes. Where the driving tip on the slider is in intermittent contact followed by impact effects, ripples of 3~5 μm traces suggest the occurrence of fretting in duralumin sliders. Nodular cast iron showed a favorable performance during running of ultrasonic motor, exhibiting a stable output performance and durable wear life.

Longitudinal–torsional vibration source consisting of two transducers with different vibration modes

The planar vibration locus is applicable to, for example, ultrasonic welding, ultrasonic machining, and ultrasonic polishing. In a previous study, we obtained the planar locus using an ultrasonic longitudinal–torsional vibration source that contained a vibration converter comprising diagonal slits to drive two frequencies. It was difficult to obtain only longitudinal or torsional vibration when using an ultrasonic complex vibration source with diagonal slits. Therefore, the versatility of the ultrasonic complex vibration source with diagonal slits was low. We have developed an ultrasonic longitudinal–torsional vibration source in which the longitudinal–torsional vibration can be controlled. The requirements for an ultrasonic vibration source were longitudinal–torsional vibration control and that the source has a planar locus. In this paper, we investigate a new type of vibration source that satisfies these requirements. It consists of two transducers, a longitudinal transducer and a torsional transducer, attached to the ends of a uniform rod with a length of one wavelength of the propagating vibration.

High-rate ultrasonic polishing of polycrystalline diamond films

We report on fast polishing of polycrystalline CVD diamond films by ultrasonic machining in a slurry with diamond particles. The material removal mechanism is based on diamond micro-chipping by the bombarding diamond particles subjected to action of an ultrasonic radiator. The treated samples were characterized with optical profilometry, SEM, AFM and micro-Raman spectroscopy. The developed method demonstrates the polishing rate higher than those known for mechanical or thermo-mechanical polishing, particularly, the surface roughness of 0.5mm thick film can be reduced in a static regime from initial value Ra≈5μm to Ra≈0.5μm for the processing time as short as 5min. No appearance of amorphous carbon on the lapped surface was revealed, however, formation of defects in a sub-surface layer of a few microns thickness was deduced using Raman spectroscopy. The polishing of a moving workpiece confirmed the possibility to treat large-area diamond films.

Research on unbounded abrasive polishing process with assisted ultrasonic vibration of workpiece

Ultrasonic-assisted machining was an effective method to improve the material removal quality especially to difficult-to-cut metal materials. The ultrasonic vibration was usually superimposed on the machining tool but seldom on the workpiece, although the ultrasonic vibration of workpiece could improve the processability of material more effectively. In this paper, a rectangle hexahedron ultrasonic sonotrode with optimized slots was developed as a platform to realize the assisted ultrasonic vibration of workpiece and the ultrasonic-assisted polishing process of austenitic stainless steel was also studied. The unbounded abrasive was selected as polishing medium, and the path compensation strategy of soft polishing tool was carried out for getting uniform polishing force. The orthogonal experiments were designed to study the optimization of ultrasonic polishing parameters and the relation between different types of ultrasonic polishing path and polishing quality. The results appear that the horizontal ultrasonic vibration of workpiece can reduce polishing force and improve polished surface roughness, which can also reinforce the proportion of plastic shear effect in the material removal process. The ultrasonic polishing path keeping consistent with workpiece vibration direction can get more uniform polishing force and better surface roughness. And the 45° oblique crossing ultrasonic path can get the maximum average polishing force reduction by 75.2 %.

Combined Ultrasonic Elliptical Vibration and Chemical Mechanical Polishing of Monocrystalline Silicon

An ultrasonic elliptical vibration assisted chemical mechanical polishing(UEV-CMP) is employed to achieve high material removal rate and high surface quality in the finishing of hard and brittle materials such as monocrystalline silicon, which combines the functions of conventional CMP and ultrasonic machining. In theultrasonic elliptical vibration aided chemical mechanical polishingexperimental setup developed by ourselves, the workpiece attached at the end of horn can vibrate simultaneously in both horizontal and vertical directions. Polishing experiments are carried out involving monocrystalline silicon to confirm the performance of the proposed UEV-CMP. The experimental results reveal that the ultrasonic elliptical vibration can increase significantly the material removal rate and reduce dramatically the surface roughness of monocrystalline silicon. It is found that the removal rate of monocrystalline silicon polished by UEV-CMP is increased by approximately 110% relative to that of conventional CMP because a passive layer on the monocrystalline silicon surface, formed by the chemical action of the polishing slurry, will be removed not only by the mechanical action of CMP but also by ultrasonic vibration action. It indicates that the high efficiency and high quality CMP of monocrystalline silicon can be performed with the proposed UEV-CMP technique.

A Study on Ultrasonic Torsional Vibration-Assisted Abrasive Waterjet Polishing of Ceramic Materials

Abrasive waterjet machining is considered as a promising technique in hard-brittle material polishing. In this paper, The ultrasonic torsional vibration is considered to apply on the workpiece to improve the abrasive waterjet polishing quality and efficiency. The process parameters in the ultrasonic torsional vibration-assisted abrasive waterjet polishing are optimized. The ultrasonic torsional vibration in the role of the abrasive waterjet polishing is investigated. The results show that the application of ultrasonic torsional vibration can effect of abrasive particle movement and increase the critical depth of the ceramic materials.

焼結ダイヤモンドの超音波研磨加工に関する基礎的研究（第3報） エンドミル底刃逃げ面の研磨

焼結ダイヤモンドの超音波研磨加工に関する基礎的研究（第3報） エンドミル底刃逃げ面の研磨

Optimization Technology and Developing of Vascular Stents

Stents have been used for the treatment of cardiovascular diseases and are often placed inside coronary arteries. The manufacture of metal stents is a challenging issue because of the features, like geometry and the material of stents. An improved manufacturing process of stents is presented. The proposed processes consist of the following steps: boring and polishing, laser cutting, vacuum annealing and surface finishing (ultrasonic cleaning, acid pickling, and electrolytic polishing). The precision boring operation is used to obtain the required wall thickness from off-the-shelf seamless tube. The laser cutting is performed to change the shape of the stent, and the finishing operations is selected to modify the surface features, like smoothness and texture of stents. 316LVM stainless steel sample with an outside-diameter of 3 mm, a wall thickness of 0.1 mm, and a length of 25 mm, had been manufactured and demonstrated the proposed manufacture technology. The surface roughness of a stent manufactured is the value of Ra 14.3 nm which basically meets the design requirement for further performance evaluation. It is hoped that the above finding can be used for future study of stents.

Ultrasonic Vibration Characteristics of Nano-Composite Ceramic in the Ultrasonic Polishing Process

The ultrasonic polishing test of the nanoZrO2-Al2O3composite ceramics is done under the two-dimensional ultrasonic polishing device, which is developed by us. In this process, the ultrasonic amplitude-frequency characteristic testing is done by the DASP software. There are certain amplitudes at some frequency points, which can be seen from the spectrum and the three-dimensional spectral array maps, but only one the largest amplitude appears. This shows the resonance points appear when the ultrasonic is passed to the nanocomposite ceramic plate after it is amplified by the horn. This phenomenon is analyzed by the second-order surface wave theory and the waves are surface waves, which are generated by surface waves. These explain the good polishing surface quality and high efficiency under the two-dimensional ultrasonic polishing in the same conditions.

Compound Finish Processes Using Grinding and Ultrasonic Electropolishing on Hole-Wall Surface

This study using ultrasonic energy transmitted into the electrolyte to assist in discharging of electrolytic product out of the machining gap in the compound finishing processes of grinding and electropolishing on hole-wall surface beyond traditional process of holes machining instead of conventional hand or machine polishing. The compound processes of grinding and ultrasonic electro polishing just require a short time to make the hole-wall surface smooth and bright in the current study. The design polishing tool includes a grinding-tool and an electrode as a hole-wall surface finish improvement that goes beyond traditional rough boring. In the experiment, the polishing tool travels across the hole-wall surface with continuous or pulsed direct current. The experimental results show that the large supply of current rating is effectively to reach the amount of the material removal and is advantageous to the finishing processes. The average effect of the ultrasonic is better than the pulsed current while the machining time needs not to be prolonged by the off-time. The finish effect is better with a high rotational speed of the polishing tool because the dregs discharge of electrochemical finishing becomes easier and is also advantageous to the finish.

Design and Dynamic Analysis of Horn for Ultrasonic Polishing

Ultrasonic polishing is an effective method to solve the bottleneck of polishing the mold cavity in mold processing, and the performance of ultrasonic horn is of utmost importance for the ultrasonic machining. In this paper the horn applicable to automatic ultrasonic polishing equipment is designed based on horn design theory, as well modal analysis and harmonic response analysis of four types of horn are carried out using Finite Element Analysis technique, which provides the basis and reference for further theoretical research and actual processing

Mechanism and Experimental Investigation on Silicon Wafer Hybrid Polishing by Ultrasonic-Elliptic-Vibration Chemical-Mechanical

Considering the technical status and existing problems of traditional silicon wafer chemical mechanical polishing (CMP), especially for the diameter of silicon wafer increasing, constantly, the surface quality and efficiency of silicon wafer polishing are becoming an urgent problem to be solved, so the research subject of ultrasonic vibration hybrid polishing new technique was proposed. By means of mechanism theoretical analysis research, firstly, the processing mechanism of hybrid polishing was studied systematically. An investigation of polishing mechanisms based on the micro-contact model between the polishing pad and the polishing surface of silicon wafer was developed. Polishing mechanism theoretical analysis shows that when ultrasonic vibrations combined with mechanical and chemical, the performance of polishing slurry is improved in the process of CMP, therefore to create favorable conditions. To verify the established theory, then, a series of experiments to investigate the traditional CMP are conducted, as well as the polishing tool with the forms of ultrasonic vibration, the polishing pad, the polishing surface quality, velocity at polishing point v, and slurry supplying Q on silicon wafer polishing. Experiment findings showed that, in the same polishing conditions, especially, hybrid polishing by ultrasonic-elliptic-vibration has gained more advantage over the effect of silicon wafer polishing. When ultrasonic-elliptic-vibration is put in polishing tool, the silicon wafer polished surface roughness Ra from the traditional method of polishing 0.077μm going down to the 0.042μm, the no-smooth rate KR which describes the polished surface morphology is significantly improved, and the material removal rate increases by 18%. Experimental research findings of the surface quality and the material removal mechanism are shown to be consistent with the theoretical analysis.

Research on a New Type of Ultrasonic Polishing Vibrator

Aiming at the ultrasonic vibration polishing technology of silicon wafer, this paper proposes a disc-shaped ultrasonic piezoelectric polishing vibrator of out-of-plant bending travalling wave. Basing on numerical analysis, the principle prototype of the polishing vibrator has been designed and produced, and then tested. This polishing vibrator can be used in polishing process of semiconductor silicon wafer.

Development of a Two-Dimensional Ultrasonic Vibration Assisted Machining Technology with Tool Vibration

As the reliable technology, ultrasonic assisted machining is widely used for brittle materials. This paper provides a two-dimensional(2D) ultrasonic vibration assisted machining technology with tool vibration using elliptical vibrator with longitudinal mode and bending mode, and set up the experiment device. Si wafer is taken as the workpiece, and single point cutting experiments for micro groove are investigated. For the further application, the ultrasonic assisted polishing experiment with wheel block is executed. Experimental results indicate that ultrasonic assisted cutting with tool vibration can improve the cutting performance and enhance the ductile removal. And the ultrasonic assisted polishing with whetstone piece makes the better surface roughness and higher material removal rate.

Ultrasonic Polishing of Electric Discharge Machined Surface Using Al<sub>2</sub>O<sub>3</sub> Suspension

The aim of this work is to investigate the possibility of improvement of surface roughness in the wire-EDMed sample by usinig ultrasonic wave and abrasive particle suspension. For this study, two-type ultrasonic polishing methods were used. Removal of the white layers on surface of EDMed sample depended largely on the movement of the suspended particles : the white layers are removed by the impact of free moving particles due to ultrasonic wave, so-called micro chipping mechanism. Even though the surface roughness was improved very slowly, 3-dimensional fine polishing was achieved in wire-EDMed micro PIM molds. These results indicated that micro polishing by ultrasonic wave using suspension is applicable to improvement of surface roughness of micro parts with 3-dimensional complex shape.

A Polishing Method of Single-Incentive Ultrasonic Elliptical Vibration for Tungsten Carbide Mould

The basic principles of ultrasonic transducer and ultrasonic elliptical vibration polishing are investigated. A new kind of single-incentive ultrasonic transducer is designed, and the finite element simulation is conducted, a polishing device is developed based on the ultrasonic elliptical vibration. The polishing experiment is adopted to polish a tungsten carbide mold with the diameter 5cm. The experimental result shows that the tungsten carbide mould surface roughness changes from the original 0.026μm to 0.017μm.

Study on Acoustic System Designing of Two Dimensional Ultrasonic Polishing without Abrasives

Acoustic system is the core component of power ultrasonic, which is designed by traditional analytic method and modal analysis with finite element analysis method. And component of the step-like horn with rectangular sections and tool head used in two dimension ultrasonic polishing without abrasives are studied, and the calculating results and modal analysis results are consistent on the whole. The harmonic response analysis for the component of horn and tool head is carried out and the three dimensional coordinates of the vibrating node on the tool head with maximal displacement are obtained. The fitting result shows that the moving trajectory of such node is ellipses, which meets the experimental requirement well. So a new way for designing acoustic system of two dimensional ultrasonic vibration through combining theoretical calculation with computer aided design may be applied.

On-Line Prediction Model of Ultrasonic Polishing Surface Roughness

In order to solve the difficulty of on-line measuring the surface roughness of workpiece under ultrasonic polishing, the artificial neural networks and fuzzy logic systems are introduced into the on-line prediction model of surface roughness. The surface roughness identification method based on fuzzy-neural networks is put forward and used to the process of plane polishing. In the end, the on-line prediction model of surface roughness is established. The actual ultrasonic polishing experiments show that the accuracy of this prediction model is up to 96.58%, which further evidence the feasibility of the on-line prediction model.

Study on Model of Ultrasonic Polishing Machining - Pulse Electro- Chemical Machining Compound Finishing for the Hard and Brittle Metals

The application of ultrasonic polishing and machining pulse electrochemical machining compound finishing is presented in the paper. The machining principle and experimental set-up of UPM-PECM compound finishing are introduced in the paper, discussing mechanism and model of the UPM-PECM in theory, and carrying on the experiment, which would co-act on hard-brittle metals in the machining. Furthermore, the material removal depth of UPM-PECM compound finishing is approximately proportional to the polishing time, and would decrease with the polishing time. This study indicates that machining velocity, machining accuracy and surface quality can be improved under UPM-PECM.