Rough Polishing Research Articles

Magnetorheological Polishing Based on Honing Vertical Mechanism for Inner Surface of Titanium Alloy Pipes

Recently, high internal surfaces for titanium alloy pipes have been required due to the increment of various applications such as aerospace components. In this work, vertical magnetorheological polishing (VMRP) is carried out to achieve high polishing performance on the internal surface of the titanium alloy pipe. A series of comparative experiments were conducted to investigate the polishing mechanism of magnetorheological polishing (MRP) fluid and enhance the polishing performance. It is shown from the experimental results that the VMRP method under the opposite polarity arrangement improves the surface roughness from 47.85% to 83.34% by reducing unwanted vibration and noise during operation. This provides nanoscale surface polishing quality, while such a precision cannot be achieved from the previous horizontal MR polishing apparatus method. It is found that under a 2700 cycle polishing time, a polishing process combining a rough and fine polishing approach with a combination of different particle diameters results in an axial surface roughness of 0.05 μm and circumferential surface roughness of 0.038 μm, respectively. It is also identified that the axial surface roughness of 0.04 μm–0.041 μm is achieved through the combination of high- and low-speed polishing process after 1602 cycles.

Fabrication and Polishing Performance of Diamond Self-Sharpening Gel Polishing Disk.

A diamond gel polishing disk with self-sharpening ability is proposed to solve the problem of glazing phenomenon in the gel polishing disks. Aluminum nitride (AlN) powder with silica sol film coating (A/S powder) is added to the polishing disk, and a specific solution is used to dissolve the A/S powder during polishing, forming a pore structure on the polishing disk. To realize the self-sharpening process, the dissolution property of the A/S powder is analyzed. The effect of A/S powder content on the friction and wear performance and the polishing performance of 4H-SiC wafers are investigated. Results showed that the friction coefficient of the polishing disk with 9 wt% A/S powder content is the most stable. The surface roughness Ra of 2.25 nm can be achieved, and there is no obvious glazing phenomenon on the polishing disk after polishing. The surface roughness of the 4H-SiC wafer is reduced by 38.8% compared with that of the polishing disk with no A/S powder addition after rough polishing, and the 4H-SiC wafer then obtained a damage-free surface with a Ra less than 0.4 nm after fine polishing by chemical mechanical polishing (CMP).

A novel ultrafast laser ablation fracture polishing method to simultaneously smoothing and improving the surface quality of Al2O3 ceramics with high roughness

Al2O3 ceramics are widely used in industry due to their excellent mechanical and physical properties. However, microcracks, voids and high surface roughness (Sa) on the surface of Al2O3 ceramic parts produced in conventional industrial or additive manufacturing have been one of the technical bottlenecks limiting their high-performance applications. In this paper, a novel method of ultrafast laser ablation fracture polishing (ULAFP) of Al2O3 ceramic parts is proposed for improving the surface quality and enhancing the mechanical properties of the polished surfaces. The ULAFP method is developed with an ultrafast laser, which can be set up as a picosecond (PS) or a femtosecond (FS) laser. The PS laser is used to form a remelting layer on the surface to eliminate surface void defects. Combining laser ablation and laser thermal stress-induced crack extension effects, the FS laser is used to rapidly remove the remelted layer and obtain a surface free of crack defects and finally implement FS laser layer-wise ablation to achieve smoother surface finish. The FS laser energy density is controlled at a critical state close to the ablation threshold of the material to avoid surface defects. This ULAFP can reduce the surface roughness (Sa5.254 μm) polishing of Al2O3 ceramics to 0.80 μm, while controlling the total ablation depth of the polishing process to below 100 μm maintaining the dimensional accuracy of the part and dramatically improving the mechanical properties of the polished surface. Compared with the original surface, the hardness and elastic modulus of the polished surface improved by 104.6% and 63.9%, respectively.

Research on the Preparation and Application of Fixed-Abrasive Tools Based on Solid-Phase Reactions for Sapphire Wafer Lapping and Polishing.

Single-crystal sapphire specimen (α-Al2O3) have been widely applied in the semiconductor industry, microelectronics, and so on. In order to shorten the production time and improve the processing efficiency of sapphire processing, an integrated fixed-abrasive tool (FAT) based on solid-phase reactions is proposed in this article. The optimal FAT composition is determined using a preliminary experiment and orthogonal experiments. The mass fraction of the abrasives is chosen as 55 wt%, and the mass ratio of SiO2/Cr2O3 is 2. Surface roughness Ra decreased from 580.4 ± 52.7 nm to 8.1 ± 0.7 nm after 150 min, and the average material removal rate was 14.3 ± 1.2 nm/min using the prepared FAT. Furthermore, FAT processing combined with chemical mechanical polishing (CMP) was shortened by 1.5 h compared to the traditional sapphire production process in obtaining undamaged sapphire surfaces with a roughness of Ra < 0.4 nm, which may have the potential to take the place of the fine lapping and rough polishing process.

A post-processing laser polishing method to improve process performance of 3D printed new Industrial Nylon-6 polymer

In this paper, the laser polishing method has been used to alleviate the asperities on the printed surface. The proposed laser polishing method is specifically used to solve industrial problems such as improving mechanical properties (flexural strength and tensile strength), surface roughness, and eco-friendly polishing of 3D-printed novel nylon-6 polymers. A series of experimentations were conducted using response surface methodology to see how changing the laser parameters affected the surface finish and the mechanical qualities of the test materials. Mechanical properties and scanning electron microscope-based surface analysis were compared with the pre-polishing workpiece. After multi-optimization, optimal laser scanning parameters resulted in a 20.2 % reduction in surface roughness, 8.27 % increment in flexural strength, and a 1.45 % increase in tensile strength. The optimum laser scanning time for samples was 0.23 min, and the energy consumption was 1.58E−05 kWh for one experiment. These findings prove that the relatively new post-processing laser polishing method improves the mechanical and surface properties of a 3D-printed nylon-6 polymer material. This new method is highly useful in the 3D printing industry to provide sustainable products.

Study on the surface interaction mechanism, corrosion inhibition effect and the synergistic action of potassium oleate and fatty alcohol polyoxy ethylene ether on copper film chemical mechanical polishing for giant large scale integrated circuit

As the feature size of integrated circuit drops down to 20–14 nm, cobalt (Co) is used as the barrier layer material for multilayer copper (Cu) wiring. The chemical mechanical polishing (CMP) process of Cu film has developed from a combined rough polishing and fine polishing to a one-step polishing, which needs to stop on the Co barrier layer. So the removal rate (RR) of Co should approach zero to meet the requirement of higher RR selection ratio of Cu and Co. Inhibitors in the Cu film slurry play an important role for controlling the RR during CMP process. In this paper, the anionic surfactant potassium oleate (PO) was selected as a key corrosion inhibitor in Cu film CMP to enhance the RR selection ratio of Cu and Co. The complexation and corrosion inhibition mechanisms between PO and Cu or Co were revealed by electrochemical measurements, X-ray photoelectron spectroscopy and scanning electron microscopy measurements. It was found that the rapid complexation of a small amount of PO with Co2+ could increase the Co RR. However, with a higher concentration of PO, the effective catalysis caused the conversion of cobaltous hydroxide to tricobalt tetraoxide, and thus resulted in a lower Co RR. With the addition of the nonionic surfactant called fatty alcohol polyoxy ethylene ether (JFCE), the morphology of the PO aggregates changes to spherical, which weakened the inhibiting effect of PO on Cu RR, and thus a higher Cu RR and RR selection ratio of Cu and Co was achieved. The synergistic action mechanism of PO and JFCE on Cu and Co surfaces was analyzed systematically. The present work provides an idea that surfactants are excellent candidates for metal inhibitors.

Review on Research and Development of Abrasive Scratching of Hard Brittle Materials and Its Underlying Mechanisms

Hard brittle materials such as ceramics and crystals are commonly utilized in various industries, including information technology, mechanical engineering, and semiconductors. These materials, known for their high brittleness and hardness but low fracture toughness, pose challenges in efficient and high-quality machining. Current abrasive machining techniques involve rough grinding, fine grinding, and polishing processes, with the latter being the most time-consuming and accounting for over half of the total machining time. Improving processing parameters in rough and fine grinding can increase machining efficiency, reduce surface and subsurface damage, and improve workpiece quality, ultimately reducing the polishing time. This paper explores the abrasive scratching of hard brittle materials, examining the nucleation and propagation of cracks causing surface and subsurface damage, and the underlying mechanisms. The research provides suggestions for enhancing abrasive machining efficiency and ensuring the surface quality of hard brittle materials.

Numerical and Experimental Investigation on the Abrasive Flow Machining of Artificial Knee Joint Surface

The titanium alloy artificial knee joint is used extensively in the current medical industry due to its distinct characteristics and properties that are like the real human knee joint, but it does need to be polished to improve its performance and service life before it can be used. Due to the complicated surface profile, the traditional abrasive flow machining technique cannot achieve a good surface finish offering uniformity and quality. Thus, in this paper, a proper constrained flow channel is designed to conduct the abrasive flow machining of the titanium alloy artificial knee joint surface to overcome these issues. A numerical study is first conducted to explore the distribution of abrasive flow velocity and pressure near the target surface in the constrained flow channel by using the COMSOL Multiphysics software, and it is found from the distribution of the dimensionless material removal rate on the target surface that the exchange of the abrasive flow inlet and outlet during the machining process is recommended to improve the surface finish uniformity. Then, the corresponding experiments are conducted to analyze the surface morphology before and after the abrasive flow machining process. It is found that the surface roughness of the target surface decreases from approximately 394 nm to 171 nm with good uniformity as well. Therefore, the proposed abrasive flow machining method with a properly designed constrained flow channel is useful for the rough polishing and fine finishing of the titanium alloy artificial joint.

Surface Generation Mechanism and Experimental Investigation of Ultrasonic Vibration Assisted Belt Flapwheel Flexible Polishing Process

To further improve the polished quality of blades surface, a new polishing process-ultrasonic vibration assisted belt flapwheel flexible polishing (UBFP) is proposed in this paper. The trajectory state of abrasives and the continuous polishing process were analyzed, and the interlace phenomenon was described. The influences of main parameters on the quality of machined surface were discussed through experiments, and the prediction models of surface roughness(Ra and Rz) were established. The results showed that lower surface roughness and less polishing marks could be achieved by UBFP, and the models were reliable that can be used in further processing and research. This study can be considered as a theoretical and experimental reference to advancing the polishing surface quality of the blisk blade.

Study on Polishing of Polycrystalline AlN Using Sol–Gel Polishing Tool

Polycrystalline aluminum nitride has extensive application prospects in substrate materials, insulating layer materials, and packaging materials. Polycrystalline aluminum nitride is sintered from powder. The traditional mechanical polishing method is easy to cause aluminum nitride grains to fall off to form pits. In this paper, to improve the polishing effect, based on the hydration of polycrystalline aluminum nitride, a sol-gel (SG) polishing tool was proposed to polish polycrystalline aluminum nitride. The polishing process was divided into rough polishing and fine polishing. The diamond particle size of the SG tool used for rough polishing was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$40\mathbf {\mathrm {\mu }}\text{m}$ </tex-math></inline-formula> . The diamond particle size of the SG tool used for fine polishing was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\mathbf {\mathrm {\mu }}\text{m}$ </tex-math></inline-formula> . Moreover, the polycrystalline AlN was processed with or without deionized water. The results showed that in the rough polishing stage, the material removal rate (MRR) of the polishing method without deionized water was four times higher than that of the polishing method with deionized water. However, in the fine polishing stage, the MRR of the polishing method with deionized water was slightly higher than that of the polishing method without deionized water. The results showed that mechanical removal is the primary material removal method in the rough polishing stage. In the fine polishing stage, hydration can improve the polishing effect of polycrystalline aluminum nitride.

Experimental Investigation on the Effect of Surface Shape and Orientation in Magnetic Field Assisted Mass Polishing.

Magnetic field assisted finishing (MFAF) technology has been widely used in industries such as aerospace, biomedical, and the optical field for both external and internal surface finishing due to its high conformability to complex surfaces and nanometric surface finishing. However, most of the MFAF methods only allow polishing piece-by-piece, leading to high post-processing costs and long processing times with the increasing demand for high precision products. Hence, a magnetic field-assisted mass polishing (MAMP) method was recently proposed, and an experimental investigation on the effect of surface posture is presented in this paper. Two groups of experiments were conducted with different workpiece shapes, including the square bar and roller bar, to examine the effect of surface orientation and polishing performance on different regions. A simulation of magnetic field distribution and computational fluid dynamics was also performed to support the results. Experimental results show that areas near the chamber wall experience better polishing performance, and the surface parallel or inclined to polishing direction generally allows better shearing and thus higher polishing efficiency. Both types of workpieces show notable polishing performance where an 80% surface roughness improvement was achieved after 20-min of rough polishing and 20-min of fine polishing reaching approximately 20 nm.

Process Optimization of Robotic Polishing for Mold Steel Based on Response Surface Method

Aimed to reduce surface roughness (Ra) and improve surface quality of mold steel, the optimizations of process parameters for robotic polishing, such as polishing pressure, feed speed and rotating speed of tool, are accomplish in this research. The optimum range of each parameter is obtained according to a single factor experiment, and the central composite design experiments on the three polishing parameters are conducted to establish a prediction model of surface roughness. Furthermore, a significance test of the prediction model is carried out through variance analysis. The optimum polishing parameters are obtained based on the analysis of response surface, and are then adopted in the polishing experiments of mold steel for validation. The experiment result of model verification indicates that the relative errors of predicted Ra ratio and actual Ra ratio are within the allowable range (maximum is 13.47%). It proves the accuracy of the roughness prediction model. Meanwhile, the experimental results of multipath polishing show that the surface roughness decreased effectively after polishing with the optimum polishing parameters. The prediction model of surface roughness and optimum polishing parameters are helpful to improve surface quality in robotic polishing for mold steel.

Research on robot bonnet polishing silicon carbide optical element machining method based on improved traveling salesman problem pseudo-random polishing path planning

Silicon carbide (SiC) has been widely used in optical components due to its excellent physical and electronic properties. However, it is very difficult to process the SiC owing to hardness and chemical stability. The robot bonnet polishing method was proposed to solve the problems existing in current polishing SiC optical elements methods, which have a low material removal rate and are expensive. First, according to Preston equation, Hertz contact theory and velocity analysis, the removal function model was established, the bonnet polishing head device was designed and put through simulation analysis. Next, aiming at the problem that the workpiece surface is prone to ripple errors during the traditional periodic polishing path trajectory processing, a pseudo-random polishing path based on the traveling salesman problem (TSP) is proposed. The path has the characteristics of multi-direction, high randomness, flatness and continuity, and compared with the raster path and random disturbance path, it is verified that the improved TSP polishing path has the ability to suppress the spatial intermediate frequency error. Then, single-point and multi-point polishing experiments are implemented to verify the accuracy and stability of the removal function. Finally, the application verification polishing processing of the SiC optical element is implemented by rough and fine polishing. The experimental results show that the bonnet polishing method and the improved TSP polishing path can effectively achieve the polishing of SiC optical elements and better suppress the intermediate frequency error of the optical processing surface. After three cycles of rough polishing and four cycles of fine polishing, the surface profile convergence rate is 72.3% and 50.8%, respectively, and the convergence rate is faster and the machining accuracy is higher.

Robot polishing control with an active end effector based on macro-micro mechanism and the extended Preston's law

There is a strong demand for automating the rough polishing process in plastic-mold manufacturing. In this study, with the active end effector being capable of fast force control and dynamic spindle control, a robot polishing control system based on a macro-micro-mechanism was built, which controls all parameters related to Preston's law and can be linked with computer-aided manufacturing. Based on the extended Preston equation, a polishing control algorithm that achieves uniform surface quality and uniform removal depth was proposed. The spherical rough polishing test on carbon steel demonstrated the efficacy of the proposed robot polishing control.

Влияние состава электролита на процесс электролитно-плазменного полирования титановых сплавов

Electrolyte-plasma polishing (EPP), also known as electrolyte-plasma treatment (EPT) has become widespread in industry as an alternative to traditional chemical, electrochemical and mechanical methods of improving the surface quality of products made of metallic materials. EPP is an innovative technology used to obtain metal surfaces with low roughness and a high gloss. Electrolyte-plasma polishing is widely used in aerospace, biomedical, precision instrumentation and other. This work is devoted to the study of the effect of the electrolyte composition on achieving the effect of polishing titanium alloys during the implementation of the EPP process. The studies were carried out on the example of polishing a titanium alloy VT6 (Ti – 6 Al – 4 V) in a three-component aqueous electrolyte containing NaF, NH2OH·HCl and KCl. It was shown that, depending on the concentration ratio of NaF and NH2OH·HCl protolyte salts, either the formation of oxide films or their anodic dissolution in the presence of a ligand can be observed on the treated surface, with the production of a clean, non-anodized metal surface, accompanied by a decrease in roughness (polishing effect). It is established that the polishing effect is achieved at a certain ratio of NaF and NH2OH·HCl, which ensures the formation of hydrogen fluoride in it in an amount sufficient to dissolve the oxide films formed on the treated surface.

Surface corrosion inhibition mechanism of sarcosine as a green novel inhibitor on a novel barrier layer material of cobalt in copper film CMP for GLSI

For integrated circuits (IC), as the technology node goes down to 20-14 nm, cobalt (Co) replaces tantalum as a new barrier layer material. The polishing process of multilayer wiring copper (Cu) film polishing is also changing from rough polishing and fine polishing to one-step polishing, and high removal rate (RR) of Cu and close to zero RR of Co are required, which can ensure a high selectivity of Cu/Co RR and stop the Cu film polishing on the barrier layer of Co. For such a goal, the way of decreasing Co RR is key and the selection of eco-friendly inhibitor of Co is essential. In this paper, the surface corrosion inhibition effect of sarcosine on Co in alkaline slurry and the inhibition mechanism were systematically investigated. The results indicated that the removal of Co was inhibited under both static and dynamic conditions with the addition of appropriate amount of sarcosine, which was also verified by scanning electron microscopy (SEM) measurements of cross sections and planes, and the corrosion area was diminished to 11.6%. Through discussing the corrosion inhibition mechanism, it was found that there were two main inhibition ways. One was by performing electrochemical experiments, and it was found that sarcosine primarily inhibited the anodic and cathodic reactions on the Co surface by forming a protective film and preventing further oxidative corrosion of Co. The others were analyzed by UV–visible test and X-ray photoelectron spectroscopy (XPS) test. It was found that sarcosine reacted with Co2+ in the glycine-based solution to generate mixed complex products deduced by new peaks emerged in XPS spectrogram, and the total amount of oxides and complexes decreased. These results indicated that sarcosine reduced the soluble complexes by competing and weakening the complex reaction with glycine. Furthermore, the Raman test indicated that Co2+ and sarcosine reacted in a 1:4 ratio to form a weakly stability water-soluble complex. The present study establishes the corrosion inhibition mechanism model of sarcosine on Co, and it also provides a new green corrosion inhibitor for Co with promising practical application.

Numerical and experimental study on the ultrasonic-assisted soft abrasive flow polishing characteristics

To resolve the low-polishing efficiency problem caused by the turbulent layer separation in soft abrasive flow (SAF) processing, an ultrasonic-assisted SAF (UA-SAF) method is proposed based on the vibration effect. The coupled computational fluid dynamics (CFD)-discrete element method (DEM) modeling method (CFD-DEM) and the dynamic mesh are used to represent the UA-SAF flow and the periodic moving boundary caused by ultrasonic vibration, while the particle-wall erosion is calculated by the Archard model. Through tracking the abrasive particle motion in the simulation, the particle-wall collision states and the particle cutting effect are revealed, which mainly includes the particle plowing and the particle impact erosion. It has been found from the simulation that the fluid turbulent motion and the fluid dynamic pressure which are the power source for the particles to obtain the anisotropic cutting kinetic energy can be strengthened obviously by the ultrasonic vibrating, which results in the increase of the probability of particle impacting the target surface, and then the particle-wall wear rate and the wear area can be improved. A set of comparative experiments, including the rough and precision polishing procedures, are then conducted to evaluate the polishing performance by using the SAF and UA-SAF, respectively. The variations of the surface roughness and the workpiece mass are obtained, and the surface morphologies are observed. The experimental results prove that the ultrasonic vibration can effectively improve the abrasive flow polishing efficiency and precision without producing cavitation erosion.

Experimental Investigation on Surface Integrity and Wear Behavior of Ti-6Al-7Nb Alloy under Rough and Trim Cut Modes of Wire Electrical Discharge Machining

Surface properties of metallic material significantly affect its fatigue, tribological and other functional properties. Titanium (Ti) alloys are hard to machine material, and therefore, wire electrical discharge machining (WEDM) is preferred over the conventional turning and milling process for machining of Ti-alloys. In the present work, surface integrity and wear behavior of Ti-6Al-7Nb have been evaluated under rough cut and trim cut modes of WEDM process. Rough cut mode resulted in high thermal damage with high surface roughness (Ra 2.34 μm), thick recast layer (Avg. 13.71 μm) and high crack density with large size micro-cracks. Significant improvement in surface properties of Ti-6Al-7Nb has obtained using trim cut mode with reduced surface roughness (0.94 μm), thin recast layer (3.51 μm), and the average crack length and average crack density reduced by 30% approximately. Energy-dispersive spectroscopy analysis showed that the trim cut mode yielded a high percentage of Ti and O elements in machined surface layers and reduced the contents of Al, Cu and C, thus favors the improved biocompatibility of Ti-alloy. Rough cut and trim cut modes of WEDM played the significant role in enhancing the surface hardness of Ti-6Al-7Nb, thus affected the coefficient of friction (c.o.f.) and wear rate. Trim cut mode resulted in lowest c.o.f. and wear rate as compared to rough cut machining and polishing. The results of the present work are highly motivated to promote the trim cut mode of WEDM as a promising manufacturing route for Ti-alloy.

Investigation of Polishing Characteristics for Aspherical Lenses Manufacturing

There were used the spherical lenses in industry conventional for long time, but new types of lenses were created during innovation processes. One type of lenses is aspherical. Two main parameters describing quality of aspherical lenses are accuracy of the form shape and surface roughness. These parameters can be obtained after last operation – polishing. Technical parameters that give the biggest influence to form shape and surface roughness were investigated in this experiment and optimal technical parameters for polishing process were established. Melted quartz ,,UVFS” was used in this research, investigations were carried out according by full factorial design. Five axis CNC machine Schneider SCPA100 was used for polishing and profilometer Nanoscan 855 was used for measurements. After analysis of results it was found out that speed of rotation and penetration depth are the most important factors in polishing process. For getting the best shape it’s necessary to use the smallest chosen values of speed of rotation and penetration depth, for getting the best surface roughness polishing parameters changing conversely. The smallest value of surface roughness Rz was 0.06 µm, and shape deviation was 2.6 µm. Optimal polishing parameters for the best quality of aspherical lenses was provided.

Impact of polishing on crystallinity and static performance of Cd[formula omitted]Zn[formula omitted]Te

This article focuses on the impact of polishing of CdZnTe crystals on the electrical properties of the resulting detectors. It is shown that the standard rough polishing of the crispy crystals by 5μm size alumina powder increases the effective surface area by a factor 3 and introduces in-depth defects. The defects affect the static current–voltage dependence and were also observed by crystallographic characterization. The depth of the defected layer was determined to be 20–25μm by a consecutive stripping of surface layers. The crystallographic results, indicating structural imperfections, fully correspond to the electrical characteristics. The results are explained by limited CdZnTe/In contact recombination velocity and enhanced generation–recombination velocity of the defected (polycrystalline) layer. The hypothesis was corroborated by a finite element computation.