Traditional Polishing Methods Research Articles

Ion beam figuring for X-ray mirrors: history, state-of-the-art and future prospects.

Synchrotron light sources require X-ray optics with extremely demanding accuracy for the surface profile, with less than 100 nrad slope errors and sub-nanometre height errors. Such errors are challenging to achieve for aspheres using traditional polishing methods. However, post-polishing error correction can be performed using techniques such as ion beam figuring (IBF) to improve optics to the desired quality. This work presents a brief overview of the history of IBF, introduces some of the challenges for obtaining such demanding figure errors, and highlights the work done at several in-house IBF facilities at synchrotron light sources worldwide to obtain state-of-the-art optical quality.

Mechanism and Study on Ball End Magnetorheological Fluid Finishing Process

The primary object of this research is to explore the capacities of BEMRF. Traditional polishing methods for glass commonly face challenges in reaching nanoscale precision and uniformity. In BEMRF, by controlling rheological properties of the MR fluid, we can tackle these challenges and potentially surpass the limitations of conventional techniques. The study includes the application of magnetorheological (MR) fluid with suspended magnetic particle abrasives to accomplish precision finishing by the manipulation of magnetic fields.

Development of a Novel Water Jet Polisher Using Soft Abrasives for Small Complex-Structure Heat Pipes of Aluminum Alloy Produced Using Additive Manufacturing.

It is a challenge to polish the interior surface of a small bent pipe with complex structures and sizes less than 0.5 mm. This is because of the fact that traditional polishing methods could destroy, block, or break the small complex structures. For a small bent pipe made of aluminum alloy produced using additive manufacturing, the defects, such as adhered powders and spatters, are easy to jam the pipe without polishing, possibly resulting in catastrophic failure for aerospace applications. To overcome this challenge, a novel water jet polisher was developed using soft polymethyl methacrylate (PMMA) abrasives. After polishing a specific area, the adhered powders on the interior surface were reduced from over 140 to 2, 3, and 6 by the soft abrasives with mesh sizes of 200, 400, and 600, respectively. The surface roughness Sa was decreased from 3.41 to 0.92 μm after polishing using PMMA abrasives with a mesh size of 200. In comparison, silica abrasives were also employed to polish the small bent pipes, leading to the bent part of pipes breaking. However, this kind of failure was absent when using soft abrasives. Computational fluid dynamics calculations elucidate that a peak erosion rate of silica abrasives for a bent pipe with a turn angle of 30° is 2.18 kg/(m2·s), which is 17 times that of soft abrasives. This is why the small bent pipe was broken using silica abrasives, whereas it remained intact when polished with soft abrasives. In addition, water jet polishing has a lower erosion rate, a relatively smooth erosion curve, and less erosion energy, leaving the bent parts intact. The developed soft abrasive water jet polisher and the findings of this study suggest new possibilities for cleaning the adhered powders and spatters and polishing the interior surface of small bent pipes with complex structures.

Evolution of point defects in mechanical cracks of fused silica after CO2 laser melting

The traditional polishing method inevitably results in subsurface cracks in the fused silica, which seriously degrades their ultraviolet laser damage resistance. CO2 laser irradiation can melt these cracks and improve their laser induced damage threshold (LIDT). Photoluminescence spectrum and SEM-FIB were employed to investigate the changes in the material microstructure at the crack location with CO2 laser melting. The density of the oxygen-deficient centers of type II (ODC II) defects decreases, while the density of the non-bridging oxygen hole center (NBOHC) defects increases after high-temperature melting. The reason for this change is related to the dihydroxylation reaction and the participation of environmental oxygen in the defect type conversion. The reduction of ODC II defects is most likely the reason for the improvement of LIDT.

A novel approach of jet polishing for interior surface of small-grooved components using three developed setups

It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm. Traditional polishing methods are disabled to polish the component, meanwhile keeping the structure intact. To overcome this challenge, small-grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer. A novel approach to multi-phase jet (MPJ) polishing is proposed, utilizing a self-developed polisher that incorporates solid, liquid, and gas phases. In contrast, abrasive air jet (AAJ) polishing is recommended, employing a customized polisher that combines solid and gas phases. After jet polishing, surface roughness (Sa) on the interior surface of grooves decreases from pristine 8.596 μm to 0.701 μm and 0.336 μm via AAJ polishing and MPJ polishing, respectively, and Sa reduces 92% and 96%, correspondingly. Furthermore, a formula defining the relationship between linear energy density and unit defect volume has been developed. The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 J mm−1 to 0.22 J mm−1. The unit area defect volume achieved via the optimized parameters decreases to 1/12 of that achieved via non-optimized ones. Computational fluid dynamics simulation results reveal that material is removed by shear stress, and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove, resulting in uniform material removal. This is in good agreement with the experimental results. The novel proposed setups, approach, and findings provide new insights into manufacturing complex-structured components, polishing the small-grooved structure, and keeping it unbroken.

Investigation of Surface Integrity of Conical Hole in Laser Polishing 440C Stainless Steel

In the machining process of 440C stainless steel using ball-end milling, the generation of machined traces is an inevitable outcome. Traditional polishing methods, when applied to the milling surfaces of small conical holes, exhibit significant limitations. However, the application of nanosecond pulsed laser polishing while maintaining dimensional integrity has proven effective in mitigating these issues. The parameters for the laser and scanning strategy were empirically determined through planar experiments. The results showed a reduction in surface roughness to a minimum value, representing a decrease of approximately 41.7%. Further validation experiments were conducted on the ball-milled surface of small conical holes. The rate of roughness reduction in these experiments surpassed that of planar surface polishing with an improvement of approximately 73.6%. The scanning strategy’s applicability was confirmed, and the post-polishing surface morphology was found to be largely in line with the prediction. The remelt layer and heat-affected zone resulting from nanosecond laser polishing were observed to be below 5 μm, significantly preserving the dimensional integrity of the conical hole’s internal surface. Moreover, nanosecond laser polishing was found to substantially enhance the surface hardness of the material, with an increase ranging from 100% to 180%. This study underscores the efficacy of nanosecond laser polishing in enhancing the internal surface of small conical holes, thereby improving the surface properties. Consequently, this method presents a reliable solution for the removal of machined traces from complex internal surfaces.

Surface polishing of CoCrMo alloy by magnetorheological polishing

Improving the surface quality of biomedical alloys is of great practical significance to the evolution of orthopaedic implant surgery. In the polishing stage, traditional polishing methods are prone to problems, such as substandard surface roughness values and poor surface morphology, which severely affect the service life of materials. The surface quality of the CoCrMo alloy treated with magnetorheological polishing was studied. First, a polishing tool was designed based on magnetic field simulations of different magnetic pole arrangements and flow field simulations of the shear behaviour of the magnetorheological polishing cluster. Second, to improve the surface quality, an equally spaced pseudo-random path was planned, and the polishing effect for this path was verified using simulations and experiments. Moreover, the effect of different process parameters, i.e., the machining gap, polishing tool rotation speed, and abrasive particle size, on the polishing forces and the surface roughness values was studied. Finally, the wettability of the modified surface of the CoCrMo alloy after polishing was tested. The results confirm the ability of magnetorheological polishing to improve the surface quality of CoCrMo alloys, which has a certain guiding significance for the development of advanced biomedical implants.

Removal mechanism of NiTi alloy by ultrasonic assisted polishing based on molecular dynamics simulation

NiTi alloy has been widely used in mechanical and electronic, aerospace, energy and transportation, petrochemical industry and various biomedicine fields due to its unique super elasticity and shape memory effect. The traditional polishing method of NiTi alloy has the problems of poor consistency of polishing quality and low efficiency, especially for some NiTi alloy with complex shapes, the traditional mechanical contact method is difficult to polish its inner surface. For some NiTi alloys prepared by additive manufacturing, due to the existence of “step effect” and “spherodizing effect”, there are unmelted powder particles on the surface, and it also needs to be polished. However, it is necessary not to destroy the original structure shape and performance, but also to achieve high efficiency, high quality and consistent polishing, so it is a technical problem. Its polishing process is still unclear, and the polishing effect needs to be improved. Therefore, in this paper, molecular dynamics method was used to study the polishing process of ultrasonic vibration diamond abrasive particles on NiTi alloy. The influences of ultrasonic vibration frequency, ultrasonic amplitude and temperature on polishing force, average friction coefficient, surface morphology, structural evolution and dislocation distribution were studied, and the microscopic material removal mechanism was revealed. The results indicate that as the ultrasonic frequency increases, the number of normal force fluctuations increases, and the elastic and plastic deformation during the scratching process also increases. With the increase of ultrasonic amplitude, the average friction coefficient decreases, and the adoption of larger vibration amplitude is conducive to the scratching process, and the average friction coefficient will increase when the temperature increases, which is not conducive to the polishing process.

The Effect of PH Value on Shear Thickening and Chemical Compound Effect Polishing Solution

When the traditional polishing method is used to process brittle materials such as lithium niobate, brittle failure is easy to occur, and many microcracks remain on the surface of the workpiece. Thus, the traditional method is not suitable for ultra-precision machining with higher surface roughness requirements. In this paper, a new type of high-performance polishing fluid with shear thickening and chemical compound effect was developed. The shear thickening effect was combined with the chemical effect, which was dedicated to the ultra-precision polishing of difficult-to-machine materials, such as optical crystals and semiconductors. The results show that the best polishing effect is achieved when the pH value is 9.5.

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.

A novel method of water bath heating assisted small ball-end magnetorheological polishing for hemispherical shell resonators

Hemispherical shell resonator (HSR) is the core component of hemispherical resonator gyro. It is a ψ-shaped small-bore complex component with minimum curvature radius less than 3 mm. Thus, traditional polishing methods are difficult to polish it. Small ball-end magnetorheological polishing method can polish the small components with complicated three-dimensional surface and obtain non-destructive surface. Therefore, this method is suitable for polishing HSR. However, the material removal rate of the ordinary small ball-end magnetorheological polishing is low, leading to long polishing time and low output of HSR. To solve this problem, a water bath heating assisted small ball-end magnetorheological polishing method is proposed in this research. The influence rule of processing parameters on the material removal rate is studied experimentally. A set of optimal processing parameters is obtained to maximize the material removal rate. Compared with the ordinary method, the material removal rate of the new method can be improved by 143%. Subsequently, an HSR is polished by the new method. The results show that the polishing time can be reduced by 55%, and the polished surface roughness can reach 7.7 nm. The new method has the great potential to be used in actual production to improve the polishing efficiency of HSR.

Fluid lubricated polishing based on shear thickening.

With the development of short wavelength optics, high requirements are put forward for the full frequency errors of optical elements, while the processing efficiency and surface quality of traditional polishing methods are difficult to meet their requirements. In this paper, a fluid lubricated polishing method is proposed by combining non-Newtonian fluid with traditional polishing methods. According to Preston equation and shear thickening principle, the tool influence function of fluid lubricated polishing is established and verified by experiments. The results show that the fluid lubricated polishing has a very good convergence ability to the full frequency error of the workpiece. In addition, the convergence rate of fluid lubricated polishing on roughness is about twice that of chemical mechanical polishing. Finally, fluid lubricated polishing extends Preston from Newtonian fluid polishing to non-Newtonian fluid polishing.

Research on Surface Quality of 38CrMoAl Polished Based on Abrasive Water Jet

Because the screw surface is slender and complex, it is difficult to process by traditional polishing methods. In order to improve the surface quality of screw, the abrasive water jet polishing (AWJP) technology was used to polish 38CrMoAl steel, which is commonly used in screw. The effects of different inlet pressure, target distance and abrasive particle size on surface roughness are analyzed. The experimental results show that with the increase of inlet pressure, the surface roughness first decreases and then increases. With the increase of target distance, the surface roughness first decreases and then increases. The smaller the abrasive particle size, the better the polishing effect.

A new method for polishing the inner wall of a circular tube with a soft abrasive rotating jet

There are limitations on the tool size and geometric constraints when the inner wall of a tube is polished by the traditional polishing method. This paper proposes a new soft abrasive rotating jet polishing (SARJP) method to polish tubes. A new tool with a stepless adjustable incident angle of the polishing fluid was designed to perform an experimental study on the inner wall of a stainless-steel tube. This study also proposes to combine the Taguchi method and response surface technique to improve the speed and quality of the optimization of the polishing process. In this paper, some mathematical statistics and graphs tools were used to comprehensively access the influence of various factors on the roughness of the inner wall of the tube. Under these optimum conditions, the average surface roughness of the inner wall decreases from 1.05 μm to 0.212 μm, and the surface roughness improvement rate is 79.8%.

A randomized controlled trial on the plaque-removing efficacy of a low-abrasive air-polishing system to improve oral health care.

While air polishing with abrasive powders has been proved efficient for sub- and supragingival application, only few studies concerning the quality of supragingival biofilm removal using the low-abrasive erythritol powder (EP) exist. The aim of the present randomized controlled trial was to clinically compare the efficacy of supragingival air polishing using EP in comparison with the rubber cup method, and to juxtapose the corresponding biofilm regrowth rates. Thirty-two young adults, suspending oral hygiene for 48 hours, were enrolled in the present double-blind short-term investigation. Using a split-mouth design, tooth polishing was conducted by means of either air polishing or rubber cups with prophylaxis paste (control). While 16 participants received air polishing in the second and fourth quadrants (and rubber cup prophylaxis in the first and third ones), the reverse sequence was applied with the remaining 16 subjects. Biofilms were assessed using the modified Quigley-Hein index (QHI), and QHI sum scores achieved both prior to and immediately after the polishing procedure, as well as 24 hours later, were assessed using a two-way analysis of variance (ANOVA), followed by Tukey's HSD to test multiple pairwise comparisons. Both methods revealed a significant reduction of QHI scores (P < .001). Compared to the rubber cup method, air polishing resulted in significantly lower scores, both after tooth cleaning and after 24 hours (P < .001). Supragingival biofilm removal by means of air polishing combined with low-abrasive erythritol seems to be more efficacious than the traditional polishing method, and should improve oral health care.

Novel rotary chemical mechanical polishing on an integral impeller

Abstract Traditional polishing on an integral impeller is labour intensive owing to its complicated curved surfaces. In this study, a novel rotary chemical mechanical polishing (R-CMP) for an integral impeller has been proposed using a developed polisher and a novel CMP slurry to improve efficiency and quality as compared to the traditional polishing method. The novel slurry consists of phosphoric acid (H3PO4), hydrogen peroxide (H2O2), nicotinic acid (NA) and silicon carbide (SiC). A model for predicting the surface roughness is established, according to the R-CMP process parameters during polishing an integral impeller, which is in good agreement with experimental results. It was found out that the polishing mechanism of R-CMP consists of four processing steps: oxidation, dissolution, chelating and removal. After R-CMP on an integral impeller, the surface roughness Ra of the blade root is reduced from 1.664 to 0.559 μm, and the thickness of the damage layer is decreased from 900 to 350 nm. The polishing time is 2 h, which is faster than the conventional manual polishing on an integral propeller by twenty times. The findings in this research open a new pathway to polish an integral high performance component with complicated curved surfaces using immersive CMP at high efficiency and high quality, without the need to exert external pressure.

Tooth polishing - A mouthful of history

Tooth polishing continues to be an integral part of clinical practice since the concept of selective polishing was introduced in the 1980s. Polishing essenitiates the removal of stains and plaque bio-film and provides a method for applying various medicaments to the teeth such as desensitizing agents .With passage of time emergence of more efficient and effective devices like jet abrasives have been introduced . Still the role of rubber cups with prophy angles cannot be overlooked as they are still being widely used and provide an economical alternative. A traditional polishing method, i.e. a rubber–cup with prophylaxis paste, has been shown to remove thefluoride–rich outer layer of the enamel thus causing significant loss of cementum and dentin over time. So alternative tooth polishing methods were developed with evidence to support alternative tooth polishing methods, dentists should familiarize themselves with contemporary methods including air polishing. The purpose of this review is to provide a comprehensive overview of recent advancements in air polishing. Clinical Relevance Scientific Rationale of Polishing:Polishing cause the abrasion of tooth surfaces. American dental hygienists association strongly recommends, do polishing of the tooth surfaces, when a dental hygienist or dentist determines a specific need for it. One should understand patient’s expectations they simply like the look and feel of teeth along with the taste and smell are next important factors. Principal findings:Polishing has been evolved from finely ground coral, eggs, shells, ginger or salt. After that various other polishing powders like flour of pumice and calcium carbonate, aluminum oxide (alumina), silicon carbide, aluminum silicate, silicon dioxide, carbide compounds, garnet, feldspar, zirconium silicate, zirconium oxide, and boron. Because of the particle size they were considered to be more abrasive. Practical Implications:With new advances finer abrasive agents with fine pa

Preparation of Flat and Smooth Copper Surface by Jet Electrochemical Machining and Electrochemical Polishing

Ultra-flat and ultra-smooth copper (Cu) surfaces are widely used as optical mirrors, heat sinks, and substrates for functional material growth. Traditional polishing methods that rely on abrasive particles are easy to induce mechanical defects such as abrasives embedding and scratches on surfaces. A new stress-free machining process is proposed in this research to fabricate an ultra-flat and ultra-smooth Cu surface by combining jet electrochemical machining (Jet-ECM) and electrochemical polishing (ECP). With the accurate manipulating of material removal rate (MRR) and planning of nozzle trajectory, an ultra-flat surface can be obtained efficiently in the Jet-ECM process. The surface roughness of the workpiece can be further improved by ECP with the same electrolyte used in the Jet-ECM process. The results show that the surface peak-to-valley (PV) value which indicated the surface form error of the Cu surface was reduced from 4.4 μm to 1.7 μm and the surface roughness Sa was reduced from 70.3 nm to 13.5 nm. The combination of Jet-ECM and ECP which share the same electrolyte and apparatus can improve the surface flatness and roughness significantly. This study improves the machining accuracy of stress-free machining methods and has great implications for the further understanding of the electrochemical removal mechanism.

Experimental Study on Continuous Laser Polishing Die Steel S136D

With the traditional polishing method the mold material will cause problems such as difficulty in processing the micro-area surface and damage to the surface of the workpiece. Laser polishing technology is an advanced and new surface processing technology that has emerged in recent years. Because laser polishing has the characteristics of good polishing quality and low thermal effect, it is very suitable for high-precision polishing of mold steel, titanium alloy and other materials. By properly controlling the process parameters such as laser energy density, scanning speed, scanning pitch and defocusing amount during laser polishing, the workpiece can be polished with high precision and the surface roughness can be quickly reduced. The processing examples in the paper further illustrate the superiority of laser polishing.

Improving the Surface Finish and other Properties of Engineering Metal Parts

The manufacture of metal parts requires post processing in most cases. These processes include heat treatment for releasing of the residual stresses resulting on the metal surface due to the excessive mechanical forces applies to cut the metal during machining, i.e. milling, turning and drilling. Another example would be the polishing of parts using different techniques. In predominant, polishing is used enhance the part’s roughness to improve the friction coefficient, to give the parts a better view and most important is to adjust the final dimensional accuracy in the microns and sub-microns scale. Traditional polishing methods include the mechanical polishing by using abrasive media or grinding machines, chemical polishing which has the benefit of reaching the inaccessible features although this method requires longer processing time in addition to the impact on environment. Sometimes the thermal deburring method is also applied for the chamfer of sharp edges and corners. In the recent years, the laser polishing technique exhibits interesting efforts and results regarding reproducibility, high control over the processing parameters which allow for the processing of different metals and non-metals materials in addition to the ultrashort processing time. This study is focusing on the laser surface polishing of metal parts, its potentials and limitations. In this study, laser surface polishing using CO2 laser beam irradiation was implemented on stainless steel Additive Manufactured produced surfaces. Two design of experiment models were implemented for the optimization of the main laser input processing parameters. The processing parameters examined were the laser beam power, the scanning speed, the number of laser scan passes, the percentage overlap of the laser tracks between the consecutive passes and the laser beam focal position. The characterization of the measured surface roughness and the modified layer microstructure were carried out using scanning electron microscopy (SEM) and 3D optical.