Surface Polishing Process Research Articles

Numerical simulation of free-surface evolution in laser polishing of 100 Cr6 bearing steel

Abstract This research focuses on the laser surface polishing process of 100 Cr6, employing a moving Gaussian heat source. It establishes a two-dimensional transient model for laser polishing, taking into account the integrated effects of fluid flow and temperature fields, as well as the combined influence of capillary and thermocapillary forces. The model was used to perform numerical simulations to study the evolution of surface morphology during the laser polishing process. The investigation specifically examines how laser power and scanning speed influence the quality of the polishing outcome. The results demonstrate that an optimal surface roughness of approximately 0.571 μm is attained at a laser power setting of 200 W and a scanning speed of 300 mm/s.

Air surface crystallization with quenched-in Fe crystallites and associated magnetomechanical properties in Fe–Si–B amorphous ribbons

The effect of surface crystallization on the magnetomechanical properties is studied for amorphous ribbons with a nominal composition of Fe80Si9B11 that are prepared with the single roller melt-spinning method. Our results indicate that the magnetomechanical power efficiency of surface crystallization ribbons is twice as higher as that of its amorphous counterpart. The surface configuration for such ribbons has been investigated through a prism of microstructures and chemical compounds. The surface crystallization with quenched-in α-Fe(Si) crystallites is confirmed by means of x-ray diffraction measurements and the surface polishing process, inducing irregular in-plane domain patterns, which are observed by magneto-optical Kerr effect microscopy. The vibrational absorption peak for polymerized B–O bonds is observed by means of a Fourier transform infrared spectrometer, being ascribed to the presence of pre-precipitated boron atoms from the crystalline film, which is confirmed by x-ray photoelectron spectroscopy. The mechanism that enhances the magnetomechanical power conversion efficiency in FeSiB ribbons with quenched-in crystallites is quite different from the ones with annealing induced “surface-interior” configurations in the previous investigations.

A surface plasmon resonance haemoglobin concentration sensor based on D‐type optical fibre with a graphene‐gold surface architecture

AbstractIn this study, a surface plasmon resonance sensor for detecting haemoglobin concentration based on a D‐type optical fibre with a graphene‐gold surface architecture is proposed. The graphene‐gold surface architecture included a 50 nm thick gold film and monolayer graphene film, which were decorated on a 10 mm long D‐type sensing region. The proposed sensor worked in wavelength interrogation mode, with the light wavelength ranging from 400 to 1100 nm. The authors realised the D‐type optical fibre surface polishing process, the gold film vacuum coating process, and the chemical‐vapour‐deposited graphene's wet transfer process. Furthermore, the fabricated sensors were used to detect the refractive index (RI) of haemoglobin samples, which varied from 1.331 to 1.346. Experiment results show that the fitted RI sensitivity of the sensor decorated with gold and graphene reaches 1874.41 nm/RIU, 4.995% higher than that of the sensor decorated only with gold. The concentration sensitivity of the sensor coated with gold and graphene film is 4.96 nm/(g/dL), and the proposed sensor can provide a resolution of 20.2 mg/dL for haemoglobin concentration detection.

Grinding characteristics of optical glass in glass molding process

A machined surface study was performed according to the surface roughness post-process polishing operation on the aspheric mold core using a diamond turning machine. Machined surface features in the bokeh image must be removed with a subsequent surface polishing process after the aspheric glass molding pressing, as surface defects are caused by the mechanical resolution of ultraprecision diamond turning machines. Therefore, in this paper, we analyze the interrelationship between surface roughness, interference frequencies, and error-approximation aspherical error values to propose a baseline measure for machined surface removal. From the results of profilometer measurements, the form error accuracy before polishing is 1.3 [Formula: see text]m, and after polishing is 0.2 [Formula: see text]m. As a result of the LUPHOS, the root mean square (RMS) average of interference frequencies before polishing is 20 nm, and after polishing is 3 nm. The machining marks are removed from the bokeh image only when the RMS roughness is maintained at 5 nm or less.

Vibration Signal-Assisted Endpoint Detection for Long-Stretch, Ultraprecision Polishing Processes

AbstractThe research reported in this article is concerned with the question of detecting and subsequently determining the endpoint in a long-stretch, ultraprecision surface polishing process. While polishing endpoint detection has attracted much attention for several decades in the chemical-mechanical planarization of semiconductor wafer polishing processes, the uniqueness of the surface polishing process under our investigation calls for novel solutions. To tackle the research challenges, we develop both an offline model and an online detection method. The offline model is a functional regression that relates the vibration signals to the surface roughness, whereas the online procedure is a change-point detection method that detects the energy turning points in the vibration signals. Our study reveals a number of insights. The offline functional regression model shows clearly that the polishing process progresses in three states, including a saturation phase, over which the polishing action could be substantially shortened. The online detection method signals in real-time when to break a polishing cycle and to institute a follow-up inspection, rather than letting the machine engage in an overpolishing cycle for too long. When implemented properly, both sets of insights and the corresponding methods could lead to substantial savings in polishing time and energy and significantly improve the throughput of such polishing processes without inadvertently affecting the quality of the final polish.

Effect of energy distribution on the machining efficiency and surface morphology of Inconel 718 nickel-based superalloy using plasma electrolytic polishing

Inconel 718 nickel-based superalloys are important aerospace materials whose precision surfaces have important applications in key aerospace components. It is significant and challenging to obtain precise surfaces of Ni-based superalloys with high efficiency and quality. Plasma electrolytic polishing (PEP) is a rapidly developing high-efficiency and high-quality metal surface polishing process and is an application process for obtaining precise surfaces of superalloys. Research on the influence of vapor gaseous envelope (VGE) behaviors and the evolution process on the polishing effect remain insufficient, although the behavior of the VGE affects the machining efficiency and surface morphology of the superalloy. In this study, the evolution process of the VGE was analyzed and simulated using experimental and simulation methods. The effects of the VGE behavior characteristics on the surface morphology and polishing efficiency were explained from the perspective of energy distribution. The experimental results showed that a discontinuous and fluctuating VGE favored the removal of materials and finishing of the workpiece surface. When the voltage exceeded 400 V, the heat flux at the gas-liquid interface exceeded the critical heat flux, and the VGE evolved from bubbles to a vapor film which deteriorated the polishing effect. Finally, the voltage range for obtaining the precision surface of the superalloy was 250–350 V, while the temperature range of the electrolyte was 70–85 °C.

Modeling and experimenting of disc hydrodynamic polishing process for ultra-smooth surfaces

The machining of ultra-smooth surfaces has always been a significant research topic in the fields of optics fabrication. In this paper, disc hydrodynamic polishing (DHDP) process with a novel polishing tool is proposed to produce ultra-smooth surface with sub-nanometer scale surface roughness (Ra < 1 nm) and undamaged sub-surface. In order to explore the principle of the ultra-smooth surface generation in the DHDP process, the material removal mechanism and evolution mechanism of micro-morphology of polished surface were firstly studied by preliminary experiments. Then, theoretical material removal and surface simulation modeling are established on the basis of computational fluid dynamics (CFD), fractal theory for rough surfaces, particle contact mechanics, and erosion mechanisms in DHDP. Finally, a series of polishing experiments was performed on fused quartz glass to verify the theoretical model, which could be applied to predict surface topography and guide the ultra-smooth surface polishing process. The results indicated that the peak-to-valley (PV) value and waviness of the workpiece were reduced in the nanometer level under the erosion action of abrasive particles. Moreover, the surface roughness Ra and PV values decreased with the increase of rotation speed and polishing time. The analysis of power spectral density (PSD) results illustrates that high rotation speed of tool and polishing time (less than 60 min) can reduce the high-spatial-frequency errors distinctly, and the longer polishing time (above 60 min) can also influence on the mid-spatial-frequency errors.

Machining Characteristics of Electrochemical Polishing Using Ultrasonic Vibration for Nanoscale High Surface Quality.

This study demonstrates a method to improve the surface quality by adding artificial vibration to the electrolyte in electrochemical polishing (ECP, electropolishing). ECP is a typical non-contact surface polishing process that has been used to improve surface quality without leaving any of the mechanical scratch marks that can arise when applying mechanical processes. ECP can polish work material via electrochemical dissolution between the surfaces of an anode and a cathode, and irregular defects are generated on the surface by impurities and bubbles generated during machining. This study confirms that our novel ECP method yields improved results over conventional ECP based on experiments using vibration electrochemical polishing (VECP) with ultrasonic vibrations. VECP minimizes nanoscale surface defects, improves surface roughness, makes it possible to quickly remove materials at nanoscale by increasing the material removal rate (MRR). Under high current density, where the electrochemical relatively reaction is active, value of the current is increased when ultrasonic vibration is added. The localized roughness of the work material was measured by atomic force microscopy (AFM) according to various electrical conditions. In addition, we also compared the overall surface quality and productivity to those obtained by conventional ECP.

A Gaussian Process Model-Guided Surface Polishing Process in Additive Manufacturing

Abstract Polishing of additively manufactured products is a multi-stage process, and a different combination of polishing pad and process parameters is employed at each stage. Pad change decisions and endpoint determination currently rely on practitioners’ experience and subjective visual inspection of surface quality. An automated and objective decision process is more desired for delivering consistency and reducing variability. Toward that objective, a model-guided decision-making scheme is developed in this article for the polishing process of a titanium alloy workpiece. The model used is a series of Gaussian process models, each established for a polishing stage at which surface data are gathered. The series of Gaussian process models appear capable of capturing surface changes and variation over the polishing process, resulting in a decision protocol informed by the correlation characteristics over the sample surface. It is found that low correlations reveal the existence of extreme roughness that may be deemed surface defects. Making judicious use of the change pattern in surface correlation provides insights enabling timely actions. Physical polishing of titanium alloy samples and a simulation of this process are used together to demonstrate the merit of the proposed method.

Human-robot collaborative reconfigurable platform for surface finishing processes

Surface polishing can be counted among the most challenging manufacturing operations, especially when high qualitative levels in terms of surface texture characteristics are requested, such as in the case of polishing operations for plastic injection moulds. Robot-based solutions for surface polishing and quality assessment operations have been proposed at the state of the art, but it still is required the involvement of skilled workers for process supervision and final tuning operations. The introduction of human-machine collaborative solutions opens new opportunities, as the use of symbiotic polishing approaches, where both the humans and the machines capabilities can be shared to improve process effectiveness. The current work proposes a human-robot collaborative approach for surface polishing processes that integrates state of the art robot-based polishing and surface quality assessment technologies in a human-safe shared working environment. As a proof of approach feasibility, the paper presents the prototype of a reconfigurable platform designed to implement a flexible human-robot collaborative scenario for execution of polishing and quality assessment operations. Preliminary demonstrative polishing sessions on simple and complex components validate the system effectiveness with respect to manufacturing efficiency and reconfigurability capabilities. The results obtained provide a first positive response that symbiotic approach can objectively improve the polishing processes.

Fabrication of Y128- and Y36-cut lithium niobate single-crystalline thin films by crystal-ion-slicing technique

Y128- and Y36-cut single-crystalline lithium niobate (LN) thin films are fabricated by the crystal-ion-slicing (CIS) technique onto LN substrates. The conditions for the successful exfoliation of submicron-thick LN thin films are independent of the wafer orientation used in the present work. Wafer bonding using benzocyclobutene (BCB) is adopted to transfer LN thin films onto substrates, instead of the generally used hydrophilic bonding, which does not need a strict surface polishing process before the bonding. A noncontact polishing method involving low-energy Ar+ irradiation is adopted to treat the sliced LN thin films. The atomic force microscopy result shows that the surface roughness of the LN thin film is reduced from 10.6 to 6.4 nm.

Investigation of Influence Factors of Surface Roughness at Corner Area in ECM Process

Surface quality of workpiece with sudden dimension change processed by electrochemical machining (ECM) is affected by many factors, such as the electrolyte flow pattern, gap between tool and workpiece electrodes, machining by-products such as gas bubbles, etc. In this paper, surface polishing process of a workpiece with sudden dimension change was considered. The electrolyte flow velocity distribution and vortex formed due to the sudden dimension change was discussed. Then, the transport of gas bubbles by the flow and its effect on the current density distribution in the electrolyte as well as the effect of current density distribution on the generation of bubbles were also investigated. Results show that current distribution on the electrode surface was greatly affected by the generation and accumulation of gas bubbles around the corner area due to the sudden dimension change of flow channel geometry, which leads to poor surface quality near the workpiece corner.

Self-reliance and independently developed high-finesse spherical ultrastable optical reference cavity

Ultra-stable reference cavity with high finesse is a crucial component in a narrow-linewidth laser system which is widely used in time and frequency metrology, the test of Lorentz invariance, and measure of gravitational wave. In this paper, we report the recent progress of the self-made spherical reference cavity, aiming at the future space application. The main function of cavity is the reference of ultra-stable laser, which is the local reference oscillation source of space optical clock. The diameter of the designed spherical cavity spacer made of ultra-low expansion glass is 80 mm, and the cavity length is 78 mm, flat-concave mirrors configuration, and the radius of the concave mirror is 0.5 m. The support structure is designed to have two 3.9 mm-radius spherical groves located at the poles of the sphere along the diameter direction (defined as support axis), and a 53 angle between the support axis and the optical axis. The mechanic vibration sensitivities of the cavity along and perpendicular to the optical axis are both calculated by finite element analysis method to be below 110-10/g. Five-axis linkage CNC machining sphere forming technology is applied to S80 mm spherical surface processing with spherical contour degree up to 0.02. After a three-stage surface polishing processes, the fused silicamirror substratessurface roughness is measured to be less than 0.2 nm (rms). Implementing double ion beam sputtering technique for mirror coating, the reflection of the coating achieves a reflectivity of 99.999% and a loss of 4 ppm for 698 nm laser. The coating surface roughness is measured to be 0.3 nm (rms). The cavity spacer and the mirror are bonded by dried optical contact. In order to improve the thermal noise characteristics of the cavity, an ultra low expansion ring is contacted optically to the outer surface of the mirror. The cavity is characterized by ring-down spectroscopy, and the finesse is around 195000. With the help of a home-made 698 nm ultra narrow line-width laser, the cavity line-width is measured to be 9.8 kHz by sweeping cavity method. A 698 nm semiconductor laser is locked to this spherical cavity by PDH technology, and the cavity loss is measured to be5 ppm.

Morphological investigation of various orthodontic lingual bracket slots using scanning electron microscopy and atomic force microscopy.

Various labial and lingual orthodontic appliances with aesthetic materials have been developed due to an increased demand in aesthetic orthodontic treatment. However, there are few reports regarding the morphology of lingual orthodontic appliances. Therefore, this study evaluates the roughness of slot surfaces of various orthodontic lingual brackets using field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Three types of stainless steel lingual brackets (Stealth® , 7th Generation® , and Clippy L® ) and one gold lingual bracket (Incognito™) with a slot size of 0.018 inches × 0.025 inches (0.457 × 0.635 mm2 ) were selected as representative lingual materials. Both FE-SEM and AFM examinations showed that the Stealth® and Clippy L® brackets had the lowest surface roughness, while the 7th Generation® bracket had the highest surface roughness. There was a significant difference in surface morphology between the types of lingual brackets, even when composed of the same material. The surface roughness of the bracket slot was dependent on the manufacturing process or surface polishing process rather than the fundamental properties of the bracket materials. There was no significant difference in the mean surface roughness of the slot floor between gold and stainless steel lingual brackets. These findings suggest that, although the gold lingual bracket is very expensive, it has great potential for use in patients with nickel allergy.

MEMS Fabrication on LTCC Substrates for RF Applications: Challenges and Perspectives

Abstract Microelectromechanical Systems (MEMS) are often used in transceiver modules, especially for telecommunication and radar applications. In this paper, we present recent progress in the development on a MEMS-on-LTCC process. We focus on the Low Temperature Co-fired Ceramic (LTCC) substrate issues and we present a successful solution for overcoming the substrate challenges through surface pre-treatment using a chemical mechanical surface polishing (CMP) process which allows us to reach the required smoothness for the fabrication of MEMS devices. We discuss various process parameters such as slurry type, rotating pad and rotation speed, and show their impact on the final surface finish. With an optimized process, the maximum roughness was decreased from more than 10μm to less than 0.5 μm over a 640 × 640 μm2 LTCC sample. Also, we present the various MEMS process steps starting with the deposition and patterning of various layers to a prototype switch highlighting the validated steps and the challenges encountered. A brief discussion of the perspectives for the integration of MEMS and LTCC technologies is also presented.

微小な炭化ﾎｳ素試料を用いたﾅﾉｲﾝﾃﾞﾝﾃｰｼｮﾝによる燃料ﾃﾞﾌﾞﾘの力学的性質計測

Although fuel debris containing hard boron carbide (B4C) control-rods should be securely removed and kept from three reactors at Fukushima Daiichi nuclear power station, owing to high-dose radiation we have no information of the debris’ properties required to develop cutting tools. In the present study, we aim to establish a nanoindentation application measuring the mechanical properties of fuel debris which have sample size of sub-millimeters. We examined how surface polishing process and sample size affect on mechanical properties measurement of the B4C particles embedded in epoxy resin. While 1mm B4C particles polished with #240 abrasive paper had elastic modulus and hardness which were practically close to those from a literature at errors of 1.6% and 9.1%, those values of 100μm particles polished with #1500 paper were significantly lower even in the modulus at a factor of 46%. We conclude that the lowered mechanical properties in the 100μm particles were caused by the inclined sample surface made by the insufficient surface polishing process.

微小な炭化ホウ素試料を用いた燃料デブリの力学的性質計測

Although fuel debris containing hard boron carbide (B4C) control-rods should be securely removed and kept from three reactors at Fukushima Daiichi nuclear power station, owing to high-dose radiation we have no information of the debris' properties required to develop cutting tools. In the present study, we aim to establish a nanoindentation application measuring the mechanical properties of fuel debris which have sample size of sub-millimeters. We examined how surface polishing process and sample size affect on mechanical properties measurement of the B4C particles embedded in epoxy resin. While 1mm B4C particles polished with #240 abrasive paper had elastic modulus and hardness which were practically close to those from a literature at errors of 1.6% and 9.1%, those values of 100μm particles polished with #1500 paper were significantly lower even in the modulus at a factor of 46%. We conclude that the lowered mechanical properties in the 100μm particles were caused by the inclined sample surface made by the insufficient surface polishing process.

An Experimental Hydrodynamic Thrust Bearing Device and Its Application to the Study of a Tapered-Land Thrust Bearing

An experimental study is presented with the main objective of understanding the hydrodynamic behavior of a tapered-land thrust bearing with fixed geometry. The experimental results were obtained using an original test rig designed at the “Institut Pprime.” Extensive instrumentation applied to the thrust bearing allows a precise evaluation of various characteristics such as the temperature, the film thickness and the friction torque. The results are in good agreement with the findings of other surveys in the literature. However, large differences between the measured parameters were observed from one pad to another. The authors demonstrate that this is due to the imperfections on the active surface, produced during machining. For a better understanding of the influence of irregularities in the flatness, the test was repeated with a thrust bearing manufactured using a high-precision surface polishing process. Experimental results with respect to the real geometry of the bearings were presented with both processes being compared. Interesting features, such as hot spots and a pressure peak, were identified on the pad at different supply temperatures and inlet pressures. This experimental study significantly advances the comprehension of the hydrodynamic behavior of tapered-land thrust bearings.

스테인리스강의 표면 결점 개선을 위한 진동 전기화학 폴리싱

This paper describes a novel hybrid surface polishing process combining non-traditional electrochemical polishing (ECP) with external artificial ultrasonic vibration. The purpose of this study is to develop an easier method for improving stainless steel surfaces. To this end, vibration electrochemical polishing (VECP), a novel ultrasonic manufacturing process, for enhancing electrochemical reaction and surface quality compared with that achieved using conventional ECP is suggested. In addition, for finding the optimized experimental conditions, the two methods are compared under various current densities. Localized roughness of the work material is measured with atomic force microscopy (AFM) and scanning electron microscopy (SEM) for obtaining detailed surface information.

Blood compatibility and adhesion of collagen/heparin multilayers coated on two titanium surfaces by a layer-by-layer technique

This paper investigates the blood compatibility and adhesion of collagen/heparin multilayers coated on cp-Ti substrates with a layer-by-layer self-assembly technique. Two surface polishing processes were used for the titanium samples: one was mechanical polishing (MP) and the other, electropolishing (EP). These samples were pretreated by being immersed in NaOH solution to obtain a negatively charged surface with hydroxyl groups and then positively charged in poly-l-lysine solution. The repeated treatment of the samples by applying heparin and collagen alternately determined the number and thickness of the multilayers. The surface topography, chemical composition, and hydrophilicity of the films were investigated by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement. The study of the adhesion of the multilayer was conducted by a nano-scratch test. The blood compatibility was evaluated by measuring the hemolysis ratio and platelet-covered area in vitro. The uncoated titanium surface was used as the benchmark. The results indicated that the anticoagulation performance of collagen/heparin multilayers on the titanium surface was superior to that of the uncoated titanium surface. The hemolysis ratios of samples with an EP Ti substrate, a relatively rougher one, were essentially lower than those of samples with an MP substrate. The increase in the multilayers' thickness enhanced their adhesion to the Ti substrate.