Search Results (47)

Ti–6Al–4V is the most commonly used alpha–beta titanium alloy, making it the most prevalent among all titanium alloys. The processed material is widely employed in aerospace, medical, and other industries requiring moderate strength, a good strength-to-weight ratio, and favorable corrosion resistance. A microfinishing process on the titanium alloy surface was conducted using abrasive films with grain sizes of 30, 12, and 9 μm. Superfinishing with abrasive films is a sequential process, where finishing operations are performed with tools of progressively smaller grains. The surface topography measurements of the workpiece were taken after each operation. The experiment was in the direction of developing a new surface smoothness coefficient considering the number and distribution of contact points so as to properly evaluate the quality of the surface finishing. The results showed that the finest-grain films gave the most uniform contact points, thus offering the best tribological characteristics; the 9 LF (micron lapping film) tools gave the smoothest surfaces (Sz = 2 µm), while the biggest-grain films, such as the 30 FF (micron microfinishing film), were less effective since large protrusions formed. This is a suitable study to explore the optimization paths for the superfinishing of titanium alloys, with implications for improving the performance and longevity of components in critical industrial applications. Full article

Aiming to address the wear and replacement inconvenience of concrete mixer liners, this study utilizes a laser cladding system to clad Fe60 alloy powder on the liner. It investigates the influence of different process parameters on the forming quality of the Fe60 alloy powder cladding layer. The optimal process parameters were obtained by weighted comprehensive evaluation, and single-layer multi-pass cladding experiments were carried out under the optimal process parameters to investigate the effects of a 30%, 40%, and 50% lap rate on the surface flatness and forming quality of the cladding layer. Using a metallographic microscope, a scanning electron microscope analysis of the macro morphology and microstructure of the cladding layer was conducted, a DPT-5 penetration flaw detector was used to observe the cracks on the surface of the multi-channel cladding, a microhardness tester and friction and wear experimental machine were used for the hardness of the cladding layer, and an abrasive wear resistance test was conducted. The results show that under the process parameters of a laser power of 900 W, powder feeding speed of 7 g/min, scanning speed of 600 mm/min, and 50% lap rate, the average microhardness of the fused cladding layer reaches 742 HV, which is 1.8 times higher than that of the liner plate, and the coefficient of friction is 0.57, which improves the liner plate’s wear resistance performance and service life. Full article

Adhesive joints play a crucial role across industries, such as aerospace, automotive, and construction, offering distinct advantages over traditional mechanical fastening methods. This study comprehensively evaluates ten surface treatments, ranging from solvent degreasing to mechanical abrasion, chemical etching, and electrochemical anodization on lap shear strength of AA 7075-T6 joints bonded with Huntsman Araldite 2011 epoxy with an ultimate goal to find the optimum surface treatment. Each treatment’s efficacy was assessed through ASTM D1002 standards using a Universal Testing Machine (UTM). Mechanical treatments, specifically sandblasting, significantly increased bond strength by up to 103.35%, whereas chemical treatment Dichromate/Sulfuric acid etching showed a maximum strength improvement of 77.9%. Electrochemical anodization, especially phosphoric-boric-sulfuric acid anodizing (PBSAA), achieved the highest strength improvement of 109%. Sandblasting emerged as the most cost-effective and efficient method for strength enhancement, whereas PBSAA is recommended for applications requiring superior strength, durability, and protection against environmental factors, which are potential requirements in aerospace applications. Full article

The present study deals with the parameters for Stainless Steel 304 and Aluminum 5083 optimized with an emphasis on surface roughness, cure time, and their impact on the tensile strength of single-lap shear joints. Utilizing a central composite design, the effects of these factors were examined. Acetone was used to polish the surfaces, and silicon carbide sheets (P30, P36, and P60) were used to abrade them. Utilizing Henkel Loctite HY4090 glue, testing was conducted in accordance with ASTM D1002 guidelines. The variables were optimized with Design-Expert 11. Maximum tensile strengths were obtained with P30 abrasion and a 48-h cure time for SS304 (Ra = 3.2 µm) and Al5083 (Ra = 5 µm), respectively. Full article

This study presents research into the unique method of depositing carbon layers onto processed surfaces, during finishing with abrasive films, on a global basis. The authors of this article are holders of the patent for this method. What makes this technology outstanding is that it integrates processes, whereby micro-finishing and the deposition of a carbon layer onto freshly exposed surface fragments is achieved simultaneously, in a single process. Among the main advantages accruable from this process is the reduction of surface irregularities, while the deposition of a carbon layer is achieved simultaneously. Ultrathin graphite layers can be widely used in conditions where other methods of reducing the coefficient of friction are not possible, such as in regard to micromechanisms. This article illustrates the application of carbon coating, end on, on a surface processed with abrasive film, containing intergranular spaces, saturated with graphite. Thin carbon layers were obtained on two substrates that did not contain carbon in their initial composition: soda–lime glass and a tin–bronze alloy. It was performed through microscopic examinations of the produced surface, roughness analyses of these surfaces, and analysis of the chemical compositions determined by two methods, namely EDS and GDOES, proving the existence of the coatings. The aim of this paper is to prove the possibility and efficiency of using graphite-impregnated lapping films in the deposition process of carbon films, with improved surface smoothness, durability, and wear resistance. The produced coatings will be tested in regard to their operational properties in further research. The authors underline the potential of this method to revolutionize surface treatment processes, due to the significant advantages it offers across various industries. Full article

Acoustic emission (AE) technology has been widely utilized to monitor the SiC wafer lapping process. The root-mean-square (RMS) of the time–domain eigenvalues of the AE signal has a linear relationship with the material removal rate (MRR). However, the existence of background noise severely reduces signal monitoring accuracy. Noise interference often leads to increased RMS deviation and signal distortion. In the study presented in this manuscript, a frequency threshold noise reduction approach was developed by combining and improving wavelet packet noise reduction and spectral subtraction noise reduction techniques. Three groups of SiC lapping experiments were conducted on a fixed abrasive pad, and the lapping acoustic signals were processed using three different noise reduction approaches: frequency threshold, wavelet packet, and spectral subtraction. The results show that the noise reduction method using the frequency threshold is the most effective, with the best coefficient of determination (R²) for the linear fit of the RMS to the MRR. Full article

Abrasive machining processes have long been integral to various manufacturing industries, enabling precise material removal and surface finishing. In recent years, the integration of non-Newtonian fluids has emerged as a promising strategy to enhance the performance and efficiency of these processes. This review paper provides a comprehensive overview of the current state of research on abrasive machining processes, including abrasive lapping, abrasive polishing, and chemical mechanical polishing, and then analyzes in detail the abrasive machining processes enhanced with non-Newtonian fluids. It explores the fundamental principles underlying the rheological behavior of non-Newtonian fluids and their application in abrasive machining, with a focus on shear-thickening fluids. The paper will begin by introducing the abrasive machining processes, including abrasive lapping, abrasive polishing, and chemical mechanical polishing. Then, the current research status of non-Newtonian fluids will be comprehensively analyzed, and we will explore the enhancement of abrasive machining processes with non-Newtonian fluids. Finally, the paper will conclude with a discussion of the future directions and challenges in the field of abrasive machining enhanced with non-Newtonian fluids. Overall, this review aims to provide valuable insights into the potential benefits, limitations, and opportunities associated with the use of non-Newtonian fluids in abrasive machining, paving the way for further research and innovation in this promising area of manufacturing technology. Full article

Abrasive waterjet (AWJ) machining offers the possibility of creating a wide range of features on mechanical parts with different degrees of complexity with a relatively high efficiency. However, after the roughing passes, the surface quality of features such as blind pockets is rather low, with unfavorable implications for surface waviness and form deviations apart from high surface roughness. Apart from the traditional methods for finishing, such as grinding or lapping, it is worth attempting either to improve the surface quality obtained during roughing by an AWJ or to integrate a post-processing step by using a pure WJ in the existing process in order to ameliorate the surface quality. Thus, in the current study, the effect of pure waterjet (WJ) post-processing of machined pockets by AWJ milling on a Ti-6Al-4V workpiece using recycled glass beads was investigated under different conditions. The findings indicate that although the different post-processing treatments by a pure WJ can affect the surface quality on average, these differences are not considerably important, probably due to an insufficient capability of material removal, which hinders the smoothing effect on machined surfaces. Thus, it was indicated that a higher number of post-processing passes under different conditions than those of the roughing pass can be more favorable for efficient post-treatment by a pure WJ. Full article

In this study, the surface of new lapping films was analyzed, and the lapping finishing process was applied to RG7 tin bronze alloy. The research focused on examining lapping films with electrocorundum grains of nominal sizes 30, 12, and 9 μm, commonly used for achieving smooth surfaces. The manufacturing process involves placing abrasive grains and binder onto a polyester tape, resulting in a heterogeneous distribution of abrasive grains. The study investigates the impact of this random distribution on the performance of lapping films during material removal. Scanning electron microscopy was used to analyze the surface structure of abrasive films, revealing distinctive structures formed by the specific aggregation of abrasive grains. This study explores the influence of different nominal grain sizes on surface finish and aims to optimize lapping processes for diverse applications. The research also delves into microchip analysis, examining the products of the lapping film finishing process. Microchips were observed directly on the abrasive tool surface, revealing insights into their morphology and distribution. The chip segmentation frequency was determined, and they amounted to approximately 0.8 to 3 MHz; these are very high frequencies, which are unique for known chip-forming processes. Full article

SiCp/Al is a difficult-to-machine material that makes it easy to produce surface defects during machining, and researchers focus on reducing the surface defects. Vibration-assisted machining technology is considered an effective method to reduce surface defects by changing the trajectory and contact mode of the abrasive. Aiming at the problem of SiCp/Al processing technology, a vibration-assisted lapping device (VLD) is designed, and elliptical motion is synthesized by a set of parallel symmetrical displacement output mechanisms. The working parameters of the device were tested by simulation and experiment, and the lapping performance was verified. Then, the effects of removal characteristics and process parameters on surface roughness and lapping force were analyzed by simulation and experiment. Simulation and experimental results show that frequency and amplitude that are too low or too high are not conducive to the advantages of NVL. The best surface quality was 54 nm, obtained at A = 8 μm and f = 850 Hz. Full article

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 R_a 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 R_a < 0.4 nm, which may have the potential to take the place of the fine lapping and rough polishing process. Full article

The influence of Cr-Al-Si-N, DLC-Si, and Cr-Al-Si-N/DLC-Si thin coatings deposited on titanium alloy (Ti-Al-Zr-Sn-Nb system) samples with different surface reliefs on wear resistance under abrasion and fretting conditions was investigated. The influence of coatings on the initial microrelief after finishing milling and lapping with micro-grained abrasive was studied by profilometry. The Martens hardness (H) and the elastic modulus (E) were determined through nanoindentation. The H/E ratio was 0.08, 0.09, and 0.13, respectively. The adhesion bond strength and H/E ratio relationship was revealed using a scratch testing analysis. Volumetric wear after 20 min of abrasive exposure was reduced by 11, 25, and 31 times for Cr-Al-Si-N, DLC-Si, and Cr-Al-Si-N/DLC-Si coatings compared to uncoated ones after milling and by 15, 32, and 35 times after lapping. Volumetric wear under fretting conditions was reduced by 1.8 and 4 times for Cr-Al-Si-N coating after milling and lapping. It was reduced by tens of times for DLC-Si coating and by hundreds of times for Cr-Al-Si-N/DLC-Si coating. The Cr-Al-Si-N/DLC-Si coating (a thickness of 3.1 ± 0.15/2.0 ± 0.1 µm) is characterized by the best combination of hardness (24 ± 1 GPa), elastic modulus (185 ± 8 GPa), and friction coefficient (0.04–0.05 after milling and 0.1 after lapping) and ensures maximum wear resistance under a wide range of loads. The novelty of the work is that those coatings were not practically under study concerning the deposition on the titanium alloy regarding typical mechanical loads such as abrasive and fretting wear but are of interest to the aviation and aerospace industry. Full article

Microlens arrays have been widely employed to control the reflection, refraction, and diffraction characteristics of light due to its distinctive surface properties. Precision glass molding (PGM) is the primary method for the mass production of microlens arrays, of which pressureless sintered silicon carbide (SSiC) is a typical mold material due to its excellent wear resistance, high thermal conductivity, high-temperature resistance, and low thermal expansion. However, the high hardness of SSiC makes it hard to be machined, especially for optical mold material that requires good surface quality. The lapping efficiency of SSiC molds is quite low. and the underlying mechanism remains insufficiently explored. In this study, an experimental study has been performed on SSiC. A spherical lapping tool and diamond abrasive slurry have been utilized and various parameters have been carried out to achieve fast material removal. The material removal characteristics and damage mechanism have been illustrated in detail. The findings reveal that the material removal mechanism involves a combination of ploughing, shearing, micro-cutting, and micro-fracturing, which aligns well with the results obtained from finite element method (FEM) simulations. This study serves as preliminary reference for the optimization of the precision machining of SSiC PGM molds with high efficiency and good surface quality. Full article

Abrasive water jetting is an effective dressing method for a fixed abrasive pad (FAP) and can improve FAP machining efficiency and the impact of abrasive water jet (AWJ) pressure on the dressing effect; moreover, the machining state of FAP after dressing has not been thoroughly studied. Therefore, in this study, the FAP was dressed by using AWJ under four pressures, and the dressed FAP was subjected to lapping experiments and tribological experiments. Through an analysis of the material removal rate, FAP surface topography, friction coefficient, and friction characteristic signal, the influence of AWJ pressure on the friction characteristic signal in FAP processing was studied. The outcomes show that the impact of the dressing on FAP rises and then falls as the AWJ pressure increases. The best dressing effect was observed when the AWJ pressure was 4 MPa. In addition, the maximum value of the marginal spectrum initially rises and then falls as the AWJ pressure increases. When the AWJ pressure was 4 MPa, the peak value of the marginal spectrum of the FAP that was dressed during processing was the largest. Full article

The paper studies the influence of diamond grinding, lapping, and polishing on the surface layer and defectiveness of the Al₂O₃/TiC and SiAlON ceramic samples. The index of defectiveness I_D, which is the product of the defect density and the defective layer’s thickness (R_t), and a method for its evaluation are proposed to quantify the defectiveness of the ceramic surfaces. Lapping reduces the R_t parameter by 2.6–2.7 times when the density of defects was decreased by 2 times. After polishing, the R_t parameter decreases to 0.42 μm for Al₂O₃/TiC and 0.37 μm for SiAlON samples. The density of defects decreases many times after polishing: up to 0.005 and 0.004, respectively. The crack resistance of the polished samples increased by 5–7%. The volumetric wear of polished samples decreased by 1.5–1.9 times compared to the ground ones after 20 min of abrasion wear. The polished samples show a decrease in the coefficient of friction at 800 °C and a decrease in the volumetric wear by 1.5 and 1.3 times, respectively, compared to the ground ones after 200 m of friction distance. The volumetric wear at high-temperature friction of sliding for polished specimens was 55% and 42% less than for the ground ones, respectively. Full article