This specialist edition features key innovations in the science and engineering of new grinding processes, abrasives, tools, machines, and systems for a range of important industrial applications. ...Topics written by invited, internationally recognized authors review the advances and present results of research over a range of well-known grinding processes. A significant introductory review chapter explores innovations to achieve high productivity and very high precision in grinding. The reviewed applications range from grinding systems for very large lenses and reflectors, through to medium size grinding machine processes, and down to grinding very small components used in MEMS . Early research chapters explore the influence of grinding wheel topography on surface integrity and wheel wear. A novel chapter on abrasive processes also addresses the finishing of parts produced by additive manufacturing through mass finishing. Materials to be ground range from conventional engineering steels to aerospace materials, ceramics, and composites. The research findings highlight important new results for avoiding material sub-surface damage. The papers compiled in this book include references to many source publications which will be found invaluable for further research, such as new features introduced into control systems to improve process efficiency. The papers also reflect significant improvements and research findings relating to many aspects of grinding processes, including machines, materials, abrasives, wheel preparation, coolants, lubricants, and fluid delivery. Finally, a definitive chapter summarizes the optimal settings for high precision and the achievement of centerless grinding stability.
Vegetable oil can be used as a base oil in minimal quantity of lubrication(MQL). This study compared the performances of MQL grinding by using castor oil, soybean oil, rapeseed oil, corn oil, ...sunflower oil, peanut oil, and palm oil as base oils. A K-P36 numerical-control precision surface grinder was used to perform plain grinding on a workpiece material with a high-temperature nickel base alloy. A YDM–III 99 three-dimensional dynamometer was used to measure grinding force,and a clip-type thermocouple was used to determine grinding temperature. The grinding force, grinding temperature, and energy ratio coefficient of MQL grinding were compared among the seven vegetable oil types. Results revealed that(1) castor oil-based MQL grinding yields the lowest grinding force but exhibits the highest grinding temperature and energy ratio coefficient;(2) palm oil-based MQL grinding generates the second lowest grinding force but shows the lowest grinding temperature and energy ratio coefficient;(3) MQL grinding based on the five other vegetable oils produces similar grinding forces, grinding temperatures, and energy ratio coefficients, with values ranging between those of castor oil and palm oil;(4) viscosity significantly influences grinding force and grinding temperature to a greater extent than fatty acid varieties and contents in vegetable oils;(5) although more viscous vegetable oil exhibits greater lubrication and significantly lower grinding force than less viscous vegetable oil, high viscosity reduces the heat exchange capability of vegetable oil and thus yields a high grinding temperature;(6) saturated fatty acid is a more efficient lubricant than unsaturated fatty acid; and(7) a short carbon chain transfers heat more effectively than a long carbon chain. Palm oil is the optimum base oil of MQL grinding, and this base oil yields 26.98 N tangential grinding force,87.10 N normal grinding force, 119.6 °C grinding temperature, and 42.7% energy ratio coefficient.
This study achieves precision grinding of face gears in the general cylindrical gear grinding machine, meeting the increasing demand for efficiency and accuracy in face gear manufacturing. The ...machining motion of face gears is more complex than that of cylindrical gears, and the general gear grinding machine cannot meet the motion of continuous generating grinding of face gears. The worm forming dressing method based on virtual center distance is proposed to replace diamond wheel deflection with worm deflection, to solve that the diamond wheel cannot be deflected when dressing the crown worm wheel. The radial feed trajectory for grinding face gears is replanned to replace the linear feed with diagonal feed, to solve that the crown worm wheel cannot deflection horizontal during face gear grinding. Finally, the tooth surface errors caused by the misalignment of the crown worm wheel during grinding are analyzed, and the numerical simulation and machining experiments are conducted for worm dressing and face gear grinding. The results show that the shape of the dressed worm is consistent with the simulation results, and the deviation of the machined face gear is within the error range of grade 5 accuracy.
Given the increasing attention to environmental and health problems caused by machining, the development of an environment-friendly grinding fluid has become an urgent task. As an ...environment-friendly grinding fluid, vegetable oil has gained considerable attention. In this study, seven typical vegetable oils (i.e., soybean, peanut, maize, rapeseed, palm, castor, and sunflower oil) were used as the minimum quantity lubrication (MQL) base oil to conduct an experimental evaluation of the friction properties of the grinding wheel/workpiece interface. With nickel-based alloy GH4169 as workpiece material, the flood grinding working condition and MQL grinding working condition (i.e., using the seven vegetable oils and paraffin oil) were selected. The evaluation of the lubrication property mainly referred to grinding force, friction coefficient, specific grinding energy, and grinding ratio (G-ratio), as well as surface morphology and surface roughness. Experimental results indicated that MQL grinding using vegetable oil achieved a lower friction coefficient, specific grinding energy, and grinding wheel wear than flood grinding. Among the grinding fluids, castor oil achieved the best lubrication property and the best surface quality of workpiece. Castor oil had a friction coefficient and specific grinding energy of 0.30 and 73.47 J/mm3, which decreased by 50.1% and 49.4%, respectively, compared with flood grinding. Moreover, various grinding fluids changed cutting forces through changes in their lubrication property and further changed G-ratio. However, lubrication property was one of factors that influenced the G-ratio. Maize oil had the highest G-ratio of 29.15. Peanut, sunflower, and soybean oil with more saturated fatty acids, castor oil with more castor acids, and palm oil with numerous palmitic acids were suitable as lubricating fluids.
•MQL grinding using different types vegetable oils was experimental evaluated.•The film-forming formation mechanism was analyzed of vegetable oil in MQL grinding.•The lubricating property of vegetable oil is better than flood lubrication.•The physicochemical properties of vegetable oil influence the lubricating property.•Lubrication property only was one influence factor of G-ratio.
Display omitted
•The grinding application of flat glass was investigated.•The best-fit MNLR models were derived to predict surface roughness.•Explanatory variables of grinding process were optimized ...by RSM.•Monte Carlo probabilistic approach was used to identify the uncertainty in proposed MNLR model.
In this paper, the performance of diamond grinding wheels was investigated. The industrial diamond crystals with a size of 140/170 mesh were utilized. The microstructure of the grinding tool was observed using a Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis Device (EDX). The experiments were designed using Box–Behnken method and optimum grinding parameters for glass were analytically determined. Experimental studies were carried out on a surface grinding machine in a flat glass factory. Grinding characteristics were examined with respect to surface roughness. The effects of grinding parameter on output responses were studied using analysis of variance (ANOVA). Probabilistic uncertainty analysis depends on Monte Carlo simulation was applied. Moreover, after the experiments using the optimized cutting parameters, the microstructure of the grinding wheels was analyzed. From results, the established model and optimization method could be employed for predicting surface roughness and this work is reliable and suitable for solving the problems encountered in machining operations. The lifetime of Cu-based grinding discs can be increased by adding Zn and Fe to the matrix material.
Abrasive material and hardness of grinding wheel are two important factors affecting the grinding efficiency and quality. In this study, two kinds of abrasive grains (i.e., zirconium corundum (ZA) ...and brown fused alumina (BA)) were used to produce eight grinding wheels, among which five with different contents of abrasive grains and four with different hardness levels. Rail grinding experiments were conducted to investigate their grinding efficiency (grinding amount of rail), grinding quality (including surface roughness, surface burn, white etching layer (WEL), and residual stress), and wear types of grinding wheels. The results show that ZA grinding wheel produced larger grinding amount, higher surface roughness, but lower level of surface burn, thinner WEL, and smaller parallel residual stress than BA grinding wheel. With the increase in grinding wheel hardness, the surface roughness and residual stress of ground rail showed decrease trends, but the thickness of WEL increased. The wear type of ZA grains was macro-fracture and the wear type of BA grains was attrition wear. With the increase in grinding wheel hardness, the wear type was changed from grain pullout wear to macro-fracture. Based on the analysis of results, the appropriate grinding wheel was recommended that can improve the grinding process and reduce the grinding cost.
•Effect of abrasive grains of grinding wheel on rail grinding behaviors was studied.•ZA grinding wheel was better than BA grinding wheel for rail grinding.•Increase in grinding wheel hardness improved grinding quality but reduced efficiency.•Wear type of grinding wheel was effected by abrasive type and wheel hardness.
The special mechanical properties of cemented carbide with high strength and hardness will cause complex stress due to excessive force and heat in the process of precision manufacturing, which will ...affect precision retention and endurance limit. Given the health and environmental threat of conventional flood cooling and the harsh processing environment of dry grinding, minimum quantity lubrication (MQL) has become an irreplaceable method to machining cemented carbide. However, the addition of nanoparticles changes the force and heat during grinding, which makes the influence on the residual stress of cemented carbide complicated. Therefore, based on the single abrasive grinding force model, the effective abrasive particle number was obtained by simulating the distribution of abrasive particles on the grinding wheel surface, and the mechanical stress model was established, which was loaded onto the workpiece in iterative attenuation mode. The thermal stress model was established based on the temperature field model. The final residual stress prediction model was obtained by determining whether the grinding process yields results and carrying out stress loading and stress relaxation. Experimental verification of the model was carried out under four different grinding conditions of YG8. The minimum friction coefficient of 0.385 was obtained under nanofluid minimum quantity lubrication (NMQL). In the precision analysis of the model, the minimum error value was 5.9% in the direction perpendicular to the feed direction of the workpiece in the dry grinding condition, which proved that the residual stress model had certain reliability.
Compared with the parameters of surface grinding, those of the curved surface abrasive belt grinding are more diverse, and the material removal mechanism is more complicated. This makes the selection ...of the parameters of the curved surface grinding process extremely difficult. This study investigates the effects of different parameters on the grinding performance of convex surface workpieces. The material removal (material removal efficiency and microchips), grinding heat (overall grinding temperature and single abrasive grain temperature), and grinding surface quality (surface roughness and removal profile) were analyzed in detail at the macro- and microscales. The effects of the grinding parameters on the above three performance indices were analyzed and discussed. The results showed that an increase in the theoretical grinding depth results in a higher material removal efficiency and grinding temperature as well as a superior ground surface quality. The effects of belt speed on the material removal efficiency and grinding temperature are less significant than those of the theoretical grinding depth. Comprehensive consideration of three indicators of grinding performance, when the theoretical grinding depth is 0.16 mm and the belt speed is 26–28 m/s, the abrasive belt grinding performance is relatively superior. Therefore, by comprehensively analyzing the grinding performance, more suitable grinding parameters can be selected to improve the grinding quality of curved workpieces.
A three-dimensional mathematical model based on homogenous coordinate transformation was developed and later experimentally validated to simulate the abrasive trajectories caused by the grit of ...grinding wheel onto the wafer. Those abrasive trajectories become the cross-hatch grinding marks on the ground wafer surface. The resulting convex or concave face profile of wafer after the grinding process as well as the abrasive trajectories which correlated to the wafer surface quality in terms of total thickness variation (TTV) can be predicted accurately. Simulations revealed that the relative orientation between the chuck table and the grinding wheel most affects TTV, followed by the offset distance if only the grinding geometry is considered. Moreover, the spindle speed should be coprime to chuck table in order to avoid overlapped trajectory, which may ensure a better grinding quality and grinding efficiency as well. Similarly, the spindle speeds for fine grinding should be coprime to rough grinding to effectively eliminate the grinding marks left by the rough grinding for better grinding quality. The model was implemented in software to generate grinding trajectories to predict wafer TTV given the process parameters such as rotational speeds and relative orientation between the grinding wheel and chuck table, which plays an essential tool for further process parameters optimization for wafer grinding.
Super abrasive diamond grinding wheels are the most promising tools for the precision machining of advanced ceramics and carbide materials. However, the efficiency of conventional conditioning of ...these tools is limited owing to high dressing tool wear, long process time, low form flexibility, and induced damage to the abrasive grains. Wire electrical discharge machining (WEDM) is an alternative method for conditioning of superabrasive grinding wheels with electrically conductive bonding materials. In this study, cylindrical plunge grinding of an alumina ceramic with a resin-bonded diamond grinding wheel is investigated. The assigned type of resin bond contains copper particles and is accordingly electrically conductive for wire electrical discharge conditioning (WEDC). Conventional (mechanical) and WEDC methods are used for generating the same profile on two similar diamond grinding wheels. As a result, the specific grinding energy was reduced up to 26% and 29% during rough and finish plunge grinding, respectively. Reduced specific grinding energy and forces, along with more effective grain protrusion and sharpness by using WEDC for profiling of grinding wheels, have contributed positively to the ground surface conditions despite the relatively rougher wheel surface topography in comparison to the conventional profiling. The more considerable reduction in the mean roughness depth (Rz) than in the arithmetical mean roughness value (Ra) (11% smaller Rz values in WEDC versus mechanical conditioning) verifies that the workpiece surface underwent less surface degradation in case of WEDC because of smaller grinding forces. Furthermore, the profile wear behavior of the workpiece ground with the WED conditioned grinding wheel was superior to the conventionally conditioned one.
PDF
