Polishing Technology Research Articles

The Grinding and Polishing Technology for Various Materials

We (Okamoto Machine Tool Works, Ltd.) present our grinding and polishing technology for various materials such as resin, Cu, BG tape, SiC, GaN. Our technology is able to grind and polish various types of materials from soft materials to hard materials. We have been developing a special grinding technology for soft materials. The technology is called HPD and enables to grind the soft materials which were not able to be ground with a standard grinding process or needed to be ground by rough grid size grinding wheels. You also had to make the grinding wheel wears a lot even the rough grid size grinding wheels are used in order to grind those soft materials due to the clogging. The HPD technology prevents this issue. Moreover, thanks to this technology, you can use high mesh wheels such as #4000 - #30,000. We believe that the HPD technology can be an effective technology for FOWLP, PLP, TSV grinding and BG tape grinding of flip-chip/high bumped wafers for flatness improvement. Our technology is not only for soft materials but also for difficult cut materials such as SiC and GaN. We developed high power and high-rigidity grinder for these materials. We are going to look through the SiC grinding result with our technology. Moreover, we have developed polishing technology for various types of materials including Si, SiC, GaN, InP, GaAs, and more. Our grinding and polishing technology can cover various types of materials. It is hoped that our technology helps your current process issues.

Thermal Conductivity and Temperature Dependency of Magnetorheological Fluids and Application Systems-A Chronological Review.

Many studies on magnetorheological fluid (MRF) have been carried out over the last three decades, highlighting several salient advantages, such as a fast phase change, easy control of the yield stress, and so forth. In particular, several review articles of MRF technology have been reported over the last two decades, summarizing the development of MRFs and their applications. As specific examples, review articles have been published that include the optimization of the particles and carrier liquid to achieve minimum off-state viscosity and maximum yield stress at on-state, the formulation of many constitutive models including the Casson model and the Herschel-Bulkley (H-B) model, sedimentation enhancement using additives and nanosized particles, many types of dampers for automotive suspension and civil structures, medical and rehabilitation devices, MRF polishing technology, the methods of magnetic circuit design, and the synthesis of various controllers. More recently, the effect of the temperature and thermal conductivity on the properties of MRFs and application systems are actively being investigated by several works. However, there is no review article on this issue so far, despite the fact that the thermal problem is one of the most crucial factors to be seriously considered for the development of advanced MRFs and commercial products of application systems. In this work, studies on the thermal conductivity and temperature in MRFs themselves and their temperature-dependent application systems are reviewed, respectively, and principal results are summarized, emphasizing the following: how to reduce the temperature effect on the field-dependent properties of MRFs and how to design an application system that minimizes the thermal effect. It is noted here that the review summary is organized in a chronological format using tables.

Effect of Micro Abrasive Slurry Jet Polishing on Properties of Coated Cemented Carbide Tools

Owing to the popularization of coating technology, physical Vapor Deposition (PVD) coated tools have become indispensable in the cutting process. Additionally, the post-treatment of coated tools applied to industrial production can effectively enhance the surface quality of coating. To improve the processing performance of coated tools, micro abrasive slurry jet (MASJ) polishing technology is first applied to the post-treatment of coated tools. Subsequently, the effects of process parameters on the surface quality and cutting thickness of coating are investigated via single-factor experiments. In the experiment, the best surface roughness is obtained by setting the working pressure to 0.4 MPa, particle size to 3 μm, incidence angle to 30°, and abrasive mass concentration to 100 g/L. Based on the results of the single-factor experiments, combination experiments are designed, and three types of coated tools with different surface qualities and coating thicknesses are obtained. The MASJ process for the post-treatment of coated tools is investigated based on a tool wear experiment and the effects of cutting parameters on the cutting force and workpiece surface quality of three types of cutting tools. The result indicates that MASJ machining can effectively improve the machining performance of coated tools.

A synergistic polishing technology by mixed abrasives with photocatalysis and fenton reaction

A synergistic polishing technology by mixed abrasives with photocatalysis and fenton reaction

Research on the modification of the tool influence function for robotic bonnet polishing with stiffness modeling

Robotic bonnet polishing (RBP) technology is widely used in the polishing process of optical components, but industrial robots have the characteristics of a wide processing range and low body stiffness. Therefore, in the actual polishing process, there are different polishing forces due to different stiffnesses, which leads to different tool influence functions (TIF) affecting the surface quality of optical components. To achieve a uniform surface quality of the components polished by the RBP, we modeled the stiffness of the robot and modified the TIF in conjunction with the Preston equation, finally verifying the accuracy of the modified model through experiments. The results of the fixed-point polishing experiments show that the maximum relative error before the TIF correction is 12.5% and the maximum relative error after the correction is 2.8% within the robot's 600mm*600mm machining range. The results of the plane polishing experiments show that the maximum relative error before the TIF correction is 13% and the maximum relative error after the correction is 1.7%. Therefore, a method for TIF corrections from RBP based on stiffness modeling has important engineering implications.

Optimization of the Morphology of the Removal Function for Rotating Abrasive Water Jet Polishing.

Abrasive water jet polishing has significant advantages in the manufacturing of complex optical components (such as high-slope optical component cavities) that require high-precision manufacturing. This is due to its processing process, in which the polishing tool does not make direct contact with the surface of the workpiece, and instead maintains a considerable distance. However, the removal functions of most existing abrasive water-jet polishing technologies do not possess strict symmetry, which significantly impacts the ability to correct surface figure errors. Therefore, this study implements rotating abrasive water-jet polishing based on traditional abrasive water jet processing to optimize the removal function, which turns it into a Gaussian form; thus, obtaining a type of removal function more suitable for CCOS polishing. This paper derives an empirical formula between the distance s' from the peak removal point of the removal function to the stagnation point and the nozzle tilt angle α, based on geometric relationships and experimental results, analyzes the relationship between material removal efficiency, nozzle tilt angle, and standoff distance. Finally, this paper verifies through experiments the validity of this empirical formula under different process parameters. Therefore, this study obtains the process conditions that allow rotating abrasive water-jet polishing technology to achieve a stable Gaussian form removal function, and the appropriate process parameters to be selected in conjunction with polishing efficiency; thereby, effectively improving the removal function's corrective ability and manufacturing efficiency. It provides theoretical support for the processing capability and process parameter selection of abrasive water-jet polishing technology, solves the problem of limited shaping capability of existing abrasive water jet tools, and significantly improves the manufacturing capability of high-end optical components.

Study on Porosity of Thermal-Sprayed Commercially Pure Aluminum Coating.

Porosity is closely related to the corrosion and wear properties of a coating processed by thermal-spraying technology, and the quantitative characterization of porosity is a crucial part of the research on coating structures. The current image analysis method often uses the mechanical polishing method recommended by ISO to measure a coating porosity. This method has been proved to be an effective method for the characterization of oxide coatings. However, due to the significant differences in the physical and chemical properties between aluminum and oxides, this method may not be suitable for aluminum coatings, and a more appropriate approach needs to be explored. In this paper, the effects of three polishing technologies (mechanical polishing, argon-ion-beam polishing, and electrolytic polishing) on the porosity measurement of pure aluminum coatings were compared and studied. The research results showed that the commonly used mechanical polishing method and more advanced argon-ion-beam polishing method could not completely reveal the pore structure because SiC particles would be embedded in the pure aluminum coatings during mechanical polishing, filling large pores. Although electrolytic polishing technology had advantages in revealing the macroporous structure, it would introduce a microporous structure and oxides, which would affect the measurement of the coating porosity. The composite polishing technology (electrolytic polishing + argon-ion-beam polishing) could perfectly reveal the pore structure in the pure-aluminum coating, and the porosity of arc-sprayed aluminum coating was 9.9%, which was close to the macroscopic true value measured using the weighing method of 10.2%.

POLISH INVENTIONS ON TECHNOLOGY OF PRIMARY EXPLOSIVES USED IN MILITARY MUNITIONS

The paper presents results of analyses of nine patent descriptions [1-9] of Polish inventions on manufacture technology of primary explosives as lead azide, lead trinitroresorcinate and tetracene, commonly used in military munitions. Five patent descriptions [1,2,7-9] were filed to the Polish Patent Office in years 1935-1975 as unclassified, and the rest patent descriptions [3-6] were applied as classified in years 1954-1962. Announcements about removing secrecy from the classified patent descriptions, were published in the News of the Polish Patent Office in year 2007.

Research on the influence of the non-stationary effect of the magnetorheological finishing removal function on mid-frequency errors of optical component surfaces.

With the continuous development of modern optical systems, the demand for full spatial frequency errors of optical components in the system is increasing. Although computer-controlled sub-aperture polishing technology can quickly correct low-frequency errors, this technology significantly worsens the mid-frequency errors on the surface of the component, which greatly inhibits the improvement of optical system performance. Therefore, we conducted in-depth research on the non-stationary effect of the removal function caused by the fluctuation in magnetorheological polishing and their influence on the mid-frequency errors of the component surface. We established a non-stationary profile model of the removal function and applied this model to simulate the distribution of mid-frequency errors on the surface of the processed component, considering the non-stationary effect. The simulation results showed that the non-stationary effect of the removal function weaken the mid-frequency ripple errors but increase other mid-frequency errors. Therefore, we first proposed the optimal single-material removal thickness corresponding to the non-stationary effect and experimentally verified the effectiveness of the optimal material removal thickness in suppressing mid-frequency errors. The experimental results showed that when the magnetorheological finishing single-material removal thickness is set to the optimal value, both the mid-frequency ripple errors and the mid-frequency RMS on the surface significantly decrease. Therefore, this work provides a basis for improving the existing magnetorheological finishing process and effectively suppressing the mid-frequency errors on the surface of processed components. It also provides theoretical and technical support for the magnetorheological processing and manufacturing of high-precision optical components. At the same time, the non-stationary effect and the corresponding analytical models has the potential to be extended to other polishing tools.

Comparative performance of subsurface and free-surface planted beds for polishing real recycled paper effluent: Influence of biomass ratio to pollutant

A polishing technology through phytoremediation was performed to reduce COD and colour from real recycled paper effluent using Typha angustifolia. Subsurface (SS) and free surface (FS) systems were operated, with batches of 10 and 26 L of effluent treated, respectively. Various numbers of plants (4 (T4), 6 (T6) and 8 (T8) plants with mass of 54, 82 and 100 g, respectively) were vegetated in each system. All treatments were run with plant control and control contaminants. After 60 days of treatment, there was significant (p < 0.05) removal of contaminants, with the highest removals of colour were 71 % (T8) and 80 % (T4); and the highest COD removals were 97 % (T8) and 89 % (T8) for SS and FS, respectively. Additionally, COD and colour removal for the treatment with eight plants (T8) in the SS system (97 % and 71 %, respectively) was significantly higher than for the treatment with four plants (T4) (COD removal = 91 % and colour removal = 50 %). This is due to the high survival percentages of plants in T8, with 100 % tolerance in the SS system which represents healthy plants undergoing the phytoremediation process with no or less fewer toxicity symptoms. Overall, the SS system performed better since the FS system faced a higher pollutant loading. The mass ratio of plants to COD for the SS system with eight plants is 37 which means for every 1 g of COD, about 37 g of plants is required to facilitate the phytoremediation process with high removal efficiency and 100 % survival of plants.

Evaluation of chemical–mechanical polishing of processed WC-Co surface structure

The cutting edges of commercial cutting tools have severe surface irregularities caused by the diamond grinding wheels that are used to form the cutting edges, which result in the introduction of lattice defects to the interior of the tungsten carbide (WC) crystal. In this study, we applied semiconductor polishing technology to finish the tool edge using a chemical–mechanical polishing grinding wheel. Microstructural analysis by backscattered electron imaging and electron backscattered diffraction revealed that WC crystal structures without any processing strain were obtained at a depth of ∼ 50 nm from the surface. We believe that this study will lead to the development of improved tool polishing technology that will prevent machining strain, and therefore, increase tool life.

Simulation and experimental study of ultrasonic-assisted shear thickening polishing of cemented carbide

In order to obtain a good surface quality of carbide inserts, an ultrasonic-assisted shear thickening polishing (UASTP) method is proposed in this paper. Using the shear thickening property of non-Newtonian fluids and combining with the principle of ultrasonic vibration, the abrasive grains wrapped by the polishing slurry carry out both flexible micro-cutting and high-frequency micro-collision on the material surface. This enables more efficient polishing of the microscopic surface of the material. In this paper, the polishing principle of this method is analyzed. The rheological characteristics of shear thickening polishing slurry are studied, and a continuity model that can adapt to nonlinear rheological behavior is proposed based on the Gross constitutive equation. The effects of fluid velocity, ultrasonic amplitude and ultrasonic frequency on polishing speed and polishing pressure in the Preston equation are studied by COMSOL Multiphysics simulation software. This method's material removal rate model is established based on the high-frequency periodic characteristics of ultrasonic action, combining the simulation results with polishing experiments, which accurately describe the variation law of material removal rate with polishing time. After polishing the carbide insert for 60 min with this method, a smooth surface is obtained with continuous surface ripple measurements and small floating values; the surface roughness is reduced from 195 nm to 16.1 nm with an improvement rate of 91.7 %, and the material removal rate reached 0.71 μm/h, which improved the surface roughness improvement rate and material removal rate by 27.6 % and 44.9 %, respectively, compared with the STP method. The experimental results show that the UASTP method is an efficient composite polishing technology to enhance the cemented carbide's surface quality further.

Research on the Application of Industrial Robot Surface Grinding and Polishing Technology in Lithium Battery Cooling Shell

In modern intelligent manufacturing, when using industrial robots to complete precision machining of lithium battery heat dissipation housing materials such as assembly, grinding, polishing, and deburring, it is not only necessary to track the position of the robot’s end effector, but also to consider the contact force generated when the actuator contacts the working environment. This project takes the research on position and force control in robot automatic polishing process as the starting point. Due to the uncertainty and high degree of nonlinearity in the control process, machine vision is introduced into the process of robotic precision machining systems, combining visual inspection systems and feedback control systems to achieve grinding trajectory planning, verify the feasibility of the control scheme, and develop a robotic lithium battery housing material processing experimental platform to meet the requirements for precision machining of the free surface of the lithium battery heat dissipation workpiece, The surface roughness parameters of the lithium battery heat dissipation workpiece after precision machining by the robot should meet the requirements of the arithmetic mean deviation of the contour.

Development of Mechanical Engineering in the Conditions of Globalization (Experience of EU Countries)

The study was carried out with the aim of evaluating and substantiating the key systemic problems of the functioning of the national engineering industry of various countries in the conditions of economic globalization. In order to achieve the goal, development trends and key relative indicators of Polish and German mechanical engineering were analyzed during and under the influence of increased economic globalization. It is analytically substantiated that during the period of economic globalization, absolute indicators increased, in particular the volume of production and the number of employees of the Polish mechanical engineering industry, but instead, its innovativeness and technology decreased significantly, and dependence on foreign enterprises increased. It was revealed that the German engineering industry, in particular the automobile industry, has undergone significant destructive changes under the influence of increased economic globalization. First of all, this is a tendency to decrease the number of cars, and a significant decrease in the share of innovative products in the volume of sold industrial products of the production of motor vehicles, trailers and semi-trailers. It is concluded that the identified destructive changes are the result of an irrational, one-sided perception of economic globalization by the main business entities of these countries. In particular, this is the failure to take into account the systemic effects of foreign enterprises and TNCs, excessive export-orientation of products, offshoring, auto-sourcing on the activities of mechanical engineering and the socio-economic development of countries in general.&#x0D; The obtained results of the study became the basis for the formation and analytical and theoretical-philosophical substantiation of the hypothesis that compliance with a high level of provision of production processes by national, not controlled from the outside, products of intermediate consumption and an optimal level of export-orientation of machine-building industries, along with a decrease in the level of monopolization in high-tech segments of the global economy, in the long term, will contribute to the satisfaction of the interests of both national economies (in particular, entrepreneurship and the social sphere), and TNCs.

Effect of elastohydrodynamic characteristics on surface roughness in cylindrical shear thickening polishing process

The shear thickening fluid exhibits a non-Newtonian characteristic, i.e. the viscosity follows a power law with the increasing shear rate. The shear thickening polishing technology has been proposed and developed to realize the precision finishing, utilizing the slurry with free abrasives prepared by the shear thickening fluid. In this paper, the formation mechanism and evolution of surface roughness in the cylindrical shear thickening polishing process is investigated in the elastohydrodynamics theoretically and experimentally. The elastohydrodynamic properties and the surface roughness are modeled by a novel solution method, based on the integration of polishing pad’s elastic deformation and slurry’s hydrodynamics. The Taguchi orthogonal tests of polishing the cylindrical AISI 52100 steel with the foam polyurethane pad were conducted, and the experimental surface roughness Ra of 9.689 nm was achieved under conditions of loading force 10 N, α-Al2O3 powder with grain size 1 μm and concentration 20 wt%, starch powder with concentration 25 wt%. According to the comprehensive analysis of variance and level average response, it is revealed that the slurry’s viscosity has a great influence on the surface roughness. The effecting mechanisms of processing factors on the surface roughness are interpreted from the perspective of effects transition in aspects of viscosity, pressure distribution and single grain’s cutting depth, interestingly exhibiting significant differences from that of traditional polishing methods.

Slurryless electrochemical mechanical polishing of 4-inch 4H–SiC (0001) and (000–1) surfaces

Silicon carbide (SiC) is a very promising next-generation semiconductor material for power device applications, and polishing technology plays an important role in improving the performance of electronics. In this regard, slurryless electrochemical mechanical polishing (ECMP) is a promising polishing technology for SiC wafer in obtaining high efficiency and high precision. In this study, slurryless ECMP of 4-inch 4H–SiC (0001) and (000–1) surfaces (Si and C faces) were investigated aiming to the industrial application. Anodic oxidation property, polishing characteristics, and mechanism of the Si and C faces in slurryless ECMP were compared and clarified. Based on the obtained results, two-step slurryless ECMP (i.e., ECMP with diamond polishing plate and then with ceria polishing plate) was conducted on 4-inch as-sliced Si and C faces. Additionally, 4-inch Si and C faces with peak-to-valley (PV) value less than 2 μm and overall surface roughness in nanometer order were obtained.

Removal of parabens from wastewater by Chlorella vulgaris-bacteria co-cultures

Anthropogenic activities have increased the dispersal of emerging contaminants (ECs), particularly of parabens, causing an escalation of their presence in wastewater (WW). Current WW technologies do not present satisfactory efficiency or sustainability in removing these contaminants. However, bioremediation with microalgae-based systems is proving to be a relevant technology for WW polishing, and the use of microalgae-bacteria consortia can improve the efficiency of WW treatment. This work aimed to study dual cultures of selected bacteria (Raoultella ornithinolytica, Acidovorax facilis, Acinetobacter calcoaceticus, Leucobacter sp. or Rhodococcus fascians) and the microalga Chlorella vulgaris in microbial growth and WW bioremediation - removal of methylparaben (MetP) and nutrients. The association with the bacteria was antagonistic for C. vulgaris biomass productivity as a result of the decreased growth kinetics in comparison to the axenic microalga. The presence of MetP did not disturb the growth of C. vulgaris under axenic or co-cultured conditions, except when associated with R. fascians, where growth enhancement was observed. The removal of MetP by the microalga was modest (circa 30 %, with a removal rate of 0.0343 mg/L.d), but increased remarkably when the consortia were used (> 50 %, with an average removal rate > 0.0779 mg/L.d), through biodegradation and photodegradation. For nutrient removal, the consortia were found to be less effective than the axenic microalga, except for nitrogen (N) removal by C. vulgaris w/ R. fascians. The overall results propose that C. vulgaris co-cultivation with bacteria can increase MetP removal, while negatively affecting the microalga growth and the consequent reduction of sludge production, highlighting the potential of microalgae-bacteria consortia for the effective polishing of WW contaminated with parabens.

Plasma Polishing as a New Polishing Option to Reduce the Surface Roughness of Porous Titanium Alloy for 3D Printing.

Porous titanium alloy implants with simulated trabecular bone fabricated by 3D printing technology have broad prospects. However, due to the fact that some powder adheres to the surface of the workpiece during the manufacturing process, the surface roughness in direct printing pieces is relatively high. At the same time, since the internal pores of the porous structure cannot be polished by conventional mechanical polishing, an alternative method needs to be found. As a surface technology, plasma polishing technology is especially suitable for parts with complex shapes that are difficult to polish mechanically. It can effectively remove particles and fine splash residues attached to the surface of 3D printed porous titanium alloy workpieces. Therefore, it can reduce surface roughness. Firstly, titanium alloy powder is used to print the porous structure of the simulated trabecular bone with a metal 3D printer. After printing, heat treatment, removal of the supporting structure, and ultrasonic cleaning is carried out. Then, plasma polishing is performed, consisting of adding a polishing electrolyte with the pH set to 5.7, preheating the machine to 101.6 °C, fixing the workpiece on the polishing fixture, and setting the voltage (313 V), current (59 A), and polishing time (3 min). After polishing, the surface of the porous titanium alloy workpiece is analyzed by a confocal microscope, and the surface roughness is measured. Scanning electron microscopy is used to characterize the surface condition of porous titanium. The results show that the surface roughness of the whole porous titanium alloy workpiece changed from Ra (average roughness) = 126.9 µm to Ra = 56.28 µm, and the surface roughness of the trabecular structure changed from Ra = 42.61 µm to Ra = 26.25 µm. Meanwhile, semi-molten powders and ablative oxide layers are removed, and surface quality is improved.

Polishing and Local Planarization High-Precision HDC Capsules by Four-Cup-Type Technology for Inertial Confinement Fusion

In inertial confinement fusion (ICF) experiments, high-density carbon (HDC) is being evaluated as an alternative to the current point-design ablator material (glow discharge plasma) due to its high density and optimal opacity, which leads to a higher energy efficiency and implosion stability. Chemical vapor deposition–coated HDC capsules have a near-perfect surface figure but a microscopically rough surface, so polishing is needed to achieve the required nanometer surface finish. Herein, HDC capsule polishing is investigated with modified four-cup-type polishing technology. The surface morphology, microstructures, and wall thicknesses of the polished capsules were examined by multiple techniques, such as an optical microscope, scanning electron microscope, X-ray radiography, and so on. The results show that the HDC capsules can be polished to a surface roughness less than 15 nm and a wall thickness nonuniformity of about 0.5 μm. The Raman spectra indicated that four-cup polishing had no obvious influence on the original surface crystallinity and phase composition of the HDC capsules. The crystallographic of the HDC capsules with different four-cup polishing times had no deterioration. This work plays an important role for the application of HDC capsules in ICF research.

An experimental investigation of sapphire grinding by porous and vitrified M0.5/1.5 diamond grinding wheel

Monocrystalline sapphire is known to be difficult to machine. Sapphire generally is machined with chemical mechanical polishing technology. However, low material removal rate (MRR) in machining gives rise to several limitations on mass manufacture of sapphire. Fixed ultrafine abrasive grinding is a promising technology for precision grinding of sapphire substrate and offers the possibility of improving manufacture efficiency. In this study, a novel porous and vitrified M0.5/1.5 diamond grinding wheel and preparation equipment are fabricated in an innovative way to precisely grinding sapphire. The experimental results demonstrate the recommended technological parameters for the grinding wheel, speed for which is below 1200 rpm, pressure below 15 N, and sapphire spindle speed lower than 30 rpm. Meanwhile, the removal mechanism of sapphire under the recommended technological parameters is in ductile grinding mode. Besides, in this study, the MRR of sapphire is 10.2 µm / h when the recommended technological parameters are adopted, the Sa of the sapphire after grinding is 0.03 µm and no depth of subface damage layer is observed.