This study investigated the effects of asymmetric surface texturing on directional friction under dry condition. Asymmetric micro-grooves were radially textured on electroless nickel phosphorous ...(Ni–P) plated disk using a single-point diamond cutting process. Using a ball-on-disk tribometer, sliding tests in clockwise (CW) and counter-clockwise (CCW) directions against polyether-ether-ketones (PEEK) material were carried out at different texture densities. Results show that asymmetric surface texturing has a strong effect on directional friction. At a texture density of 70 %, the friction coefficient in the CW direction increased by 28.1 % compared to the CCW direction. The greatest increase in friction coefficient, 61.3 %, was observed during CW rotation at the lowest texture density compared to the reference untextured surface.
Abstract In order to develop a method for the production of crack-free cladding layers, we combined surface texturing technology with laser cladding, establishing a multi-field coupled numerical ...simulation model. A separate investigation was conducted into the temperature, stress, and fluid fields in laser cladding processes with and without texturing, seeking optimal cladding parameters, and conducted experiments. The results of the numerical simulations indicate that pre-set texturing effectively reduces the temperature gradient during the cladding process, thereby making the thermal cycle curve smoother. The residual stresses in the X, Y, and Z directions are reduced by 34.84%, 3.94%, and 50.22%, respectively. The introduction of texturing reduces the internal flow velocity of the melt pool, preventing the occurrence of a double vortex effect. Experimental results show that the residual stresses in the X, Y, and Z directions of the predefined textured cladding layer are reduced by approximately 41%, 8%, and 47%, respectively, compared to the non-textured cladding layer. This effectively improves the surface roughness and internal grain size of the cladding layer, with no significant defects at the metallurgical bonding positions, providing a reference for future improvements in cladding layer quality.
•2D Kinematic analysis, 3D simulation coupled with experimental investigation by a self-made setup was performed to explore the effect of the milling parameters and vibrating parameters on the ...generation of micro-textured surface in feed direction ultrasonic vibration assisted end milling process. Two key parameters, i.e. η and λ, was defined and supposed to be significant to the actual tool track and empty cutting time and finally the surface finishing.•Three typical surface texture, which are “micro-rib”, “micro-scale” and “micro-wave”, were simulated and experimentally fabricated at low spindle speed, medium spindle speed and high spindle speed, respectively. The predictive surface textures are in consistent with those of experiment. At a certain spindle speed (a certain spindle speed means a certain η), λ influences the size of overlapped area of multiple cutting and thus produce an effect on the size of fabricated micro-structure.•The surface topographies and roughnesses of the obtained three kinds of micro-textured surfaces, together with their tribological behaviors under strave oil lubrication condition ,were investigated. As results, the fabricated micro-textures cause the deterioration of surface roughness in most experimental cases owing to the peak-valley micro structure resulting from excited vibration. However, the micro-textures studied in this case all make a great contribution to the improvement of surface friction property, particularly in term of load bearing capacity due to the lubricant absorption and reservation function of micro-texture. Too low spindle speed may lead to much increase in surface roughness, which then affect the surface tribological performance adversely, and medium spindle speed is preferable to achieve micro-textured surface with better load bearing capacity.
Surface with certain macro/micro/nano structure has been earning more and more attentions owing to its good tribological behavior. However, some complex texture pattern is hard to fabricate, which hinders its wide application. In this study, feed direction ultrasonic vibration assisted milling (FDUAM), was proposed to realize the easy fabrication of micro-textured surface. Based on tool mapping principle, kinematic analysis was carried out aiming to explore the effect of main process parameters on tool trajectory, and also a surface topography simulation model was build. The numerical analysis results were validated by comparing results with experimental data. Three surface texture patterns, which are “micro-rib”, “micro-scale” and “micro-wave”, were realized at low spindle speed, medium spindle speed and high spindle speed, respectively. A preliminary friction test was at last conducted to investigate the tribological behaviors of various micro-textured surfaces. As results, it is found that the final surface topography is greatly influenced by the matching of vibrating parameters and milling parameters, two key parameters, i.e. η and λ, was supposed to be significant to the actual tool path and empty cutting time and finally the surface finishing. Friction test shows that although the fabricated micro-textures lead to the deterioration of surface roughness in most experimental cases, the three fabricated micro-textures studied in this case all make a great contribution to the improvement of surface friction property, particularly in term of load bearing capacity.
This study uses nanofluids and laser surface texturing (LST) synergistically to enhance tribological performance. ZrO2-MoDTC hybrid nanoparticles of different concentrations were used as lubricant ...additives in base oil. Microtextured patterns of different shapes and sizes were designed and created on steel pin surface by laser ablation, and their tribological performances were assessed using a pin-on-disc tribometer. Appropriate circular dimple textured (DT) surfaces with 0.5 wt% ZrO2-MoDTC hybrid nanofluid produced outstanding friction reduction and anti-wear performance than cross-groove textured (GT) and untextured (UT) surfaces. The average friction coefficient of DT reduced by approximately 24–28% and 57–60% than GT and UT surfaces, respectively. Analysis of the worn surface showed that the synergetic influences of the nanofluid and LST produced excellent tribological performance.
•ZrO2-MoDTC hybrid nanofluids and laser textured surface was prepared successfully.•Sustainable lubrication mechanism of ZrO2-MoDTC as lubricating oil additives on textured steel surface were investigated.•The synergistic effect of the combined LST and nanofluids for reducing friction and wear was revealed.•The formation mechanism of the composite lubricating film was investigated.•In order to enhance tribological performance of hybrid nanofluids, surfaces topographies with optimized parameters will be essential.
The paper presents the geometric structure of the surface, hardness and the results of tribological tests for TiO2 layers obtained by the ALD technique. The geometrical structure of the surface ...before and after the tribological tests was assessed using a confocal microscope with interferometry mode. An instrumental indentation was used to measure nanohardness. Model tribo tests were carried out for reciprocating motion under conditions of dry friction and friction lubricated with artificial saliva and saline. The tests showed that the TiO2 samples showed lower wear and higher hardness.
Surface texture topography affects the performance of industrial parts, such as precision and service life. Different tool postures may lead to various texture topographies in five-axis milling. In ...this paper, surface texture topography quality and texture trend evaluation indexes are proposed considering the influence of tool posture in five-axis milling. Based on the evaluation, the ranges of tool posture angles corresponding to surface texture topographies of different characteristic are obtained through surface texture topographies classification. The result can provide reference for singularity avoidance in path planning and machining error compensation in five-axis milling. The influence of tool posture change on the surface texture quality could be avoided while adjusting the tool posture angle in the determined range. Firstly, the general tool cutting edge point expression with the typical structure parameters of the end mills is proposed. The general digital model of surface texture topography is established with the improvement of the unit time calculation and computing vertex judgment in simulation. Secondly, several evaluation indexes are proposed to represent the quality and the overall trend of the surface texture topography with digital extraction of indexes realized on the surface digital model. On this basis, the classification of the surface texture topographies and the determination of the range of tool posture angle for each class of textures are proposed. Thirdly, the evaluation and classification of the ball-end milling plane texture topographies are carried out, which divide the texture topographies into zero-inclination angle textures and non-zero inclination angle textures. The surface textures are further divided to detailed five categories with the tool posture angle range determined. Different tool posture angles of the same class are used to generate a texture topography for the comparison to verify the evaluation indexes and the classification result. Finally, the plane cutting orthogonal experiments are carried out. The general surface digital model is verified by the comparison in surface texture characteristic of different types of mills between digital model and machined surface. Based on the ball-end milling plane classification result, the machined surface textures and extracted indexes are compared to verify the effectiveness of the proposed evaluation indexes and the classification result. The fillet-end milling surface textures are further classified and verified based on the method above. In addition, the spherical surface textures of ball-end milling are carried out for further verification.
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•The general surface texture digital model of five-axis milling is proposed with typical structure parameters of end mills.•The quality indexes and texture trend indexes of surface texture topography are proposed considering the influences of tool posture in five-axis milling.•The classification of textures is presented to obtain the range of tool posture angle of different classes of textures.•Different tool posture angles of the same class are used to generate a texture morphology for the verification.•The plane cutting experiments are proposed to verify the effectiveness of the surface texture model and the classification.
This work investigates the mechanisms for friction reduction in textured journal bearings. The measured friction of laser-etched connecting-rod big-end shells was compared with a non-textured ...reference under engine-like conditions. Experiments covered several working conditions, and the friction and lubricant film temperatures were measured for three texture configurations. The origin of the verified friction reduction was explored using a numerical model that simulates the hydrodynamic lubrication and global thermal effects. The simulation results accurately matched the friction measurements, revealing that the microscopic mechanisms of reduction in lubricant shear stress and effective viscosity due to texture-induced cavitation act simultaneously to reduce the friction coefficient for the textured shells. The findings have practical applications for the optimal design of textured hydrodynamic bearings.
•Friction in textured journal bearings was experimental and numerically investigated.•A journal bearing model with thermal effects was validated using experimental data.•Textures reduced the lubricant shear stress and viscosity and lowered friction.•The shear area reduction mechanism for textured hydrodynamic bearings was confirmed.
