Polishing Technology Research Articles

Stress Modification in Multi-Layer Walls of Expanded Pressure Vessels

The paper deals with a stress modification in thick-walled multi-layer pressure vessels widely used in every field of high pressure technology. The stress modification is obtained by means of initial (residual) stresses which are introduced into the vessel structure during the manufacturing process. Certain technological parameters are determined. Their realization leads to the equivalent stresses being more uniformly distributed across the vessel wall under the operating pressure. As a consequence the load carrying capacity of the multi-layer vessel increases as compared with the solid wall without additional treatment. The analytical approach as well as the finite-element method are used to solve the problem. A special attention is focused on the unconventional original Polish technology in which the internal pressure is applied to form the thick multi-layer cylinder wall through subsequent expansion of thin layers. The advantages of the proposed method are illustrated by the numerical example of the expanded multi-layer high-pressure vessel with modified initial stress distribution.

Polishing experiments of thin mirror with magnetic medium assistant polishing technology

The thin mirrors are widely used in active optical system. In this letter, magnetic medium assistant polishing (MMAP) technology and device are discussed for thin mirrors optical finishing. The principle of MMAP is introduced, the magnetic tool for polishing is designed, and the removal function of magnetic polishing tool is studied. On the basis study of the material removal function especially removal property in the edge region, the tool-path is optimized, and the dwell time distribution of computer-controlled MMAP is researched. The glass thin mirror is polished by MMAP technology. The diameter of the work-piece equals S22201 150 mm and the thickness is 5 mm. The initial surface error is 0.19\lambda (root mean square (RMS)) , and after two steps fabrication, the final surface error reaches 0.02\lambda. The experimental rsults verify that the technology is effective for thin mirrors finishing.

Research on the Optimization of the Bonnet Polishing Tool

Bonnet polishing is a practical and economical polishing technology for the fabrication of precision optical components. Its removal function is controlled by many parameters, and much research has been performed on them in the past few years. However, most of the previous research has been focused on the inner pressure of the bonnet, the rotation speed of the spindle, the precession angle, the bonnet decrement, etc. The deformation of the bonnet under the inner pressure has received relatively little attention. This paper demonstrates the deformation of the bonnet under the inner pressure and its effect to the contact area and the bonnet decrement. It also proposes two solutions, one is to add an enhancement layer on the bonnet; the other is to design a novel bonnet contour which is aspheric but turns to spherical under the effect of the inner pressure. The latter one is proved that it’s effective to reduce the deformation to the polishing process.

Highly efficient polishing technology for glass substrates using tribo-chemical polishing with electrically controlled slurry

The outstanding advantage of the novel polishing technology developed by the authors is a considerable reduction in cerium oxide consumption for polishing of glass substrates. This has been realized by introducing tribo-chemical polishing method along with a technique to control the movement of abrasives using an AC electric field. In this paper, we have analyzed the characteristics of the new polishing technique from the viewpoint of slurry distribution in the polishing area under various electric field conditions using a digital image processing and its influence on polishing performance using the experimental setup consisting of high speed polishing method under AC electric field. The results confirmed the increase of slurry distribution in the polishing area under appropriate AC electric field conditions and consequently led to enhanced removal rate, which was 2.5 times higher than that of the conventional CMP (chemical mechanical polishing) method. Furthermore, in spite of enhanced removal rate the surface roughness was comparable to CMP method.

Study on Technological Parameters of Polishing Large Aspheric Elements

Large aspheric elements in giant laser facility are fabricated using computer controlled rapid polishing technology. The technological parameters are main influencing factors of efficiency. Base on Preston hypothesis, linear relationship of material removal with polishing pressure, polishing velocity and other conditions are established. According to the material removal function model of computer controlled rapid polishing, the removal function is simulated using MATLAB software. The influencing factors of volume removal efficiency are analyzed. In practice, the optimum polishing parameters are eccentricity 0.4, rotational velocity of principal axis 330 rpm, rotational velocity of polishing pad -600 rpm.

Study of the Wheel of Abrasive Belt Based on Forming Polishing Technology

The wheel of abrasive belt is a special-shaped coated abrasive which has the advantage of good polishing quality, long life, and high efficiency, low cost and so on. Base on the features of the wheel of abrasive belt, through analyzing the basic motion relation of forming polishing spiral surface screw, the wheel of abrasive belt’s profile shape curve could be calculated by establishing the contact line equation of screw spiral surfaces with the wheel of abrasive belt rotating surfaces. Software to verify the correctness of the profile shape calculated, and in accordance with the wheel of abrasive belt profile shape curve to programming NC program. Start with the dressing experiments of the wheel of abrasive belt. Through analysis and research to get the wheel of abrasive belt’s profile shape curve meet the forming polishing standard.

Study on Effect upon the Roughness of Bearing Outer Ring from the Jet Pressure in the Strengthening and Polishing Process

This paper first analyze effect upon the surface roughness on the bearing outer ring from the jet pressure in the strengthening and polishing process theoretically, and then verify the validation of the theory in experiments, finally, it is concluded that the jet pressure should be reduced and about 0.4MPa for better in the strengthening and polishing process, under the circumstance of meeting the roughness requirements and considering the various factors, so as to lay a foundation to further research the relation between the strengthening and polishing technology and the surface roughness on the bearing outer ring.

Experimental Investigation of Polishing Character of Rotating Magnetic Polishing Fluids

In the face of the mechanical part of shape complex, the surface is difficult to be finished by the automatic and effective methods, but the magnetic fluid mixed with the polishing and cutting particles has motion characteristics in magnetic field. This paper introduces a kind of polishing technology which can rotate magnetic polishing fluid in the influence of magnetic field. The viscosity and hardness of magnetic polishing fluid change under the magnetic field, and the magnetic polishing fluid rotates in the fluence of the magnetic stirring apparatus, when machining magnetic in the liquid in polishing, and fixed in the liquid in proper position. When we select the best position in the magnetic polishing fluids and immerse the workpiece in the magnetic polishing fluids, the magnetic fluids rotate and move relatively to the workpiece. The friction between the magnetic fluid and the surface of workpiece has the finishing efficiency. The experiment is carried out to study the relation of the roughness and polishing and location on the home-made polishing laboratory platform in detail. The experimental results show that the rotating magnetic polishing liquid can be used for polishing the workpiece in super smooth processing, which is much better than polishing abrasive alone in reducing surface roughness. The study opens a new field for the application of the magnetic fluid. However, the direction of the field, the speed of the movement, and the polishing time of the process parameters still needs further research.

Implementing a grolishing process in Zeeko IRP machines

The removal of mid-spatial-frequency errors is a challenging issue in most subaperture polishing technologies. A novel "grolishing" technology has been developed to deal with grinding errors of spatial wavelengths from 1 to 50 mm with the help of power spectral density analysis and filter theory. This grolishing process was implemented on Zeeko's IRP polishing machine, on which all the subsequent polishing was performed. This has greatly reduced the process time. Although different abrasive have been used, the process is self-contained. The process parameters have been optimized to leave an edge upstand of peak-to-valley of 1 μm over a width of 40 mm.

CVD Diamond Film Polishing Based on Accelerant Theory

CVD diamond has become the mainstream trend for the development of diamond. Its ultra precision machining is one of the key technologies for expanding the application of CVD diamond film. The efficient polishing method is studied, called accelerant polishing technology, which can lower the activation energy needed in diamond graphitization by the accelerant action of transition metal. It accelerates reaction rates of graphitization and promotes the implementation of diamond’s removal mechanism. Experimentation results indicate that the polishing method is one new type of precision polishing technology with low cost and high efficiency.

Study on Polishing Technology of GaAs Wafer

GaAs are one of the most important semiconductor followed silicon, GaAs wafers are the mostly used substrates for fabricating integrated circuits (ICs). So the quality of ICs depends directly on the quality of GaAs wafers. A series of processes are required to manufacture high quality GaAs wafers. This paper reviews the literature on polishing technology of GaAs wafers, covering the history, summarizes the effects of slurry’s chemical and physical characters such as pH, oxidants, abrasive grit, velocity, and temperature in the polishing process. It also discusses some possible topics for future research.

Research on Flexible Bonnet Polishing Process Method and Related Technology

Bonnet tool polishing is one kind of methods that can obtain higher surface quality of the ultra precision processing for producing flat, aspheric and other mould free surface, etc. The latest development and research results on bonnet polishing technology at home and abroad were reviewed. The core technologies of bonnet polishing were analyzed, including polishing principles, polishing tool, the rate of material removal, edge control, dwell time, path planning etc. The results show that the bonnet polishing method is an economic, efficient, practical and high precision polishing technology.

Processing Parameters Optimization and Experiment Research of Automatic Polishing Technology for Free Surface of Dies

Abstract: A kind of automatic polishing equipment for free surface of dies is designed, which is fixed on the backbone of numerical control machine. Processing parameters optimization are gotten by the orthogonal analysis method based on experiment data and surface roughness is about 1.0μm, which provides good basis of practical research and application of accurate working for free surface of dies.

Research on Automatic Polishing Technology for Free Surface of Dies Based on Fuzzy Control

In order to solve the problem of removing uneven and improve processing quality for automatic polishing free curve surface of dies, a new technique based on fuzzy control is put forward in the thesis. Polishing pressure and rotate speed of grinding wheel will be changed according to the curvature of free curve surface, the results of simulation and experiment show the method is excellent for removing material evenly, reducing the values of surface roughness and improving the surface quality of parts, which provides good basis of practical research and application of accurate working for free surface of dies.

Application of Multi-Mode Combined Polishing to Optical Manufacturing

The object of this study is the application of Multi-mode combined polishing, which is combination of polishing technology mode and current high-end CNC machining technology, to optical manufacturing. Detailed analysis and explanation of application of multi-mode combined polishing to optical manufacturing are made, from the perspectives of basic information and Preston equation of multi-mode combined polishing. And thus demonstrate the crucial role and significance of application of this technology in further promote and enhance the precision of optical processing operation efficiency.

Development of an AC Electric Field-Applied Tribochemical Polishing Technology to Promote High-Efficiency Polishing for Glass Substrates (Image Analysis of Dynamical Slurry Behaviours and Polishing Characteristics under AC Electric Field)

This paper deals with the investigation conducted on the mechanism of the polishing technology, to which AC electric field is applied. For the analysis of the slurry dynamical behaviors, we used a digital image processor. In this research, we have also worked to develop a novel high-efficiency polishing technology applying AC electric field for the glass substrates for IT devices. When AC electric field was applied to, the slurry behavior was found to have better stability than the one without AC electric field. Furthermore, good polishing rates were obtained under high-relative rotation speed between the glass substrates and polishing pad. This suggests that the friction heat generated between the glass substrate and polishing pad, which promote tribochemical reactions, improves polishing rate. This latest polishing technology makes the removal rate two times better than the conventional polishing and produces excellently smooth surface.

Review on Ultra-precision Polishing Technology of Aspheric Surface

The requirement of profile accuracy and surface quality for aspherical surface has become higher and higher with the expanding application range and raising application precision demand.As the finishing process,the ultra-precision polishing method for aspherical surface is drawing great attention from countries around the world.For improving the precision and efficiency of aspheric surface polishing,an understanding of the mechanisms of material removal in ultra-precision aspheric polishing,as well as the sub-surface damage imparted,is essential prerequisites.Historical progress of aspheric polishing techniques is plotted,and based on the development of aspheric polishing methods,the present advanced ultra-precision aspheric polishing methods are described with emphasis on the processing mechanisms and examples.The different ultra-precision aspheric polishing methods are compared in terms of sub-surface damage and edge effect.And aiming to high finishing accuracy and high efficiency,the probable further trend of ultra-precision aspheric polishing technology is forecasted.

Polishing Sapphire Substrates by 355 nm Ultraviolet Laser

This paper tries to investigate a novel polishing technology with high efficiency and nice surface quality for sapphire crystal that has high hardness, wear resistance, and chemical stability. A Q-switched 355 nm ultraviolet laser with nanosecond pulses was set up and used to polish sapphire substrate in different conditions in this paper. Surface roughnessRaof polished sapphire was measured with surface profiler, and the surface topography was observed with scanning electronic microscope. The effects of processing parameters as laser energy, pulse repetition rate, scanning speed, incident angle, scanning patterns, and initial surface conditions on surface roughness were analyzed.

The Polishing Technology for Glass Substrates Using Tribo-Chemical Reaction and Electrical Slurry Control

The outstanding advantage of the novel polishing technology developed by the authors has the ability to reduce the cerium oxide abrasives consumption for polishing of glass substrate. This has been realized by introducing tribo-chemical polishing method along with controlled abrasives technique using an AC electric field. In this paper, we attempted to analyze the characteristics of the new polishing technique from the viewpoint of slurry distribution in the polishing area under various electric fields using a digital image processing and evaluated the polishing performance. We confirmed the increase of slurry distribution in the polishing area under the AC electric field due to attractive force generated on polar water molecules which suppressed the scattering of the slurry. Consequently, the removal rate was enhanced. Furthermore, the removal rate of electrical tribo-chemical polishing technology was 2.5 times higher than the conventional CMP (Chemical Mechanical Polishing) method, while the surface roughness was comparable.

HEALTH TECHNOLOGY ASSESSMENT IN POLAND AND SCOTLAND: COMPARISON OF PROCESS AND DECISIONS

We compared Polish and Scottish Health Technology Assessment (HTA) process in order to elicit recommendations for future development of HTA methodological guidelines in Poland. We studied the differences between Polish and Scottish HTA methodological guidelines. HTA recommendations issued by Polish HTA agency (AHTAPol) in the period January 1 through December 31, 2008, were benchmarked to HTA guidance published by Scottish Medical Consortium (SMC) for the same drug technology. The Scottish HTA methodological guidelines were more instructive in terms of clinical and economic evaluations than Polish guidelines. SMC evaluated forty-eight of sixty-eight drug technologies appraised by AHTAPoL. There were thirty drug technologies that received similar guidance in both countries and eighteen with contradictory HTA recommendations. In Scotland, there were more positive HTA recommendations than there were in Poland. While comments about efficacy or safety were commonplace among reasons for negative recommendations in Poland, insufficient justification of treatment's cost in relation to benefits was the most often cited reason for rejection in Scotland. SMC tended to recommend restricted use to specific sub-populations for several drug technologies negatively appraised by AHTAPoL. The comparison between SMC and AHTAPoL suggests that there is potential room of improvement of the Polish HTA methodological guidelines. Comparative effectiveness and safety, subgroup analysis, and adaptation of models to local settings were identified as key areas for further development of Polish HTA methodological guidelines.