Grinding Wheel Research Articles

Experimental Investigation of Cr12 Steel Under Electrostatic Minimum Quantity Lubrication During Grinding

In this work, electrostatic minimum quantity lubrication (EMQL) has been applied in grinding. When the droplets were charged, it could promote penetrability in the processing area. The electric field formed between the charged droplets and the surface of Cr12 die steel could affect the hardness of the workpiece surface. The grinding mechanism of EMQL has been revealed under different charging voltage by analyzing the wetting angle of droplets and the hardness of Cr12 surface. The reduction of grinding force (11.5% to 49%), surface roughness (10% to 22.1%), and the increase in grinding ratio (1.9% to 27.3%) and surface quality of EMQL under various charging voltages were studied. The results showed that the wetting angle decreased when the droplets were charged. Compared to MQL, the charged lubricant droplets with better penetrability are easier to penetrate and spread on the contact surface between the grinding wheel and the workpiece, thereby improving the lubrication of the friction interface and obtaining better grinding performance. Moreover, we also found that the positively charged EMQL not only effectively improves the penetrability of droplets but reduces the hardness of the Cr12 surface. Thus, the grinding performances under positively charged EMQL are always better than these under negatively charged when grinding Cr12.

Effect of addition on microstructures and mechanical properties of cBN/Cu-Zn-Ti composites via the pulse electric current sintering

In order to improve the performance of metal-bonded grinding wheels, the cBN/Cu-Zn-Ti composites were fabricated by pulse current sintering with several different Co contents (i.e., 5, 10, and 15 wt%) were added. The specimen microstructure, interfacial analysis and fracture morphology of pulse current sintering cBN grain were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The mechanical properties of hardness, wear resistance, and three-point bending strength of the fabricated specimens were tested. The electrochemical properties was also tested. The specimen shape fabricated by pulse current sintering using the composite Cu-Zn-Ti alloy doped by Co was better than pure Cu-Zn-Ti alloy. The microscopic analysis revealed that TiB2 and TiN were maintained between the Cu-Zn-Ti composites and cBN. With the addition of Co, the hardness, flexural strength and wear resistance of the specimens are improved. The new phase CoTi3 enhancing strength of the metal composite via the Orowan mechanism. The S5 specimen containing 15 wt% Co particles has the highest flexural strength, which is 485.83 MPa and satisfies the requirements of high speed grinding. Meanwhile, when the Co content reaches 10 %, the lowest friction coefficient (0.217) and lowest wear rate (0.81 mg) are achieved for the sample. With the addition of Co, the corrosion resistance of the material is significantly improved.

Wafer chamfering grinding wheels dressing via dynamic deflection laser beam

Wafer chamfering forming grinding wheels (WCF) is a kind of V-shaped circular groove forming wheel with a large diameter and small grooves. In this study, a dynamic deflection laser beam method is presented to improve the dressing quality of WCF. The compensation effect of deflected laser on the surface laser energy density of materials was analyzed, and the blocking effect caused by oversized deflection angle of laser beam was analyzed. A C-W model was proposed for laser dressing of WCF. Based on C-W model, trajectory planning for laser dressing was carried out, and dressing experiments were completed. The results show that the contour transition of the grinding wheel is more smooth. Compared to single direct laser beam dressing method and static deflection laser dressing method, the contour exhibits better roundness and the PV values reduced to 5.1μm. Surface observation revealed strip-shaped patterns and some flocculent metamorphic layer. The SEM result shows that there are no obvious crack defects on the surface.

Diamond parameter design and assessment of a novel 3D printed diamond grinding wheel with linear cooling channels

To solve the problems of a metal-bonded diamond grinding wheel in grinding hard and brittle material parts, such as easy blockage, poor cooling capacity, and insufficient self-sharpening, a 3D printed diamond grinding wheel with linear cooling channels (GWLCC) was proposed, and its basic parameters were analyzed in this paper. The new grinding wheels with different diamond parameters were prepared by using dual-filament 3D printing technology. The hardness and relative density of the grinding wheels were measured, and the grinding tests of red sandstone were carried out. The experimental results show that high volume concentration and fine granularity of diamond particles are more likely to cause agglomeration behavior, resulting in more pores and cracks, thus reducing the relative density of the grinding wheel and matrix strength, but this is conducive to the exposure of diamond particles. The grinding efficiency of the diamond grinding wheel is positively correlated with the volume concentration and grain size of the diamond. Besides, a test of the grinding performance of GWLCC with different diamond parameters in grinding different brittle-hard materials was carried out, and the suitability of the new 3D printed grinding wheel and its potential to improve grinding performance has been proven. The GWLCC suitable for different hard and brittle materials are summarized.

Simulation and Experimental Study of Ultrasonic Vibratory Grinding of Internal Splines

As an important component of mechanical transmission systems, internal splines are widely used in aerospace, industrial equipment, and other fields. However, internal splines are prone to deformation and shrinkage after heat treatment. At present, most internal splines with a pitch circle diameter greater than φ60 mm can be processed and shaped by ordinary corundum grinding wheels, but there is no effective processing method for the shaping of small- and medium-sized internal splines. This paper establishes a single abrasive material removal model; uses Abaqus to simulate three-body free grinding; and analyzes the effects of abrasive rotation angle, rotation speed, and grinding depth on material removal under different conditions. By comparing the tooth lead deviation and tooth direction deviation before and after internal spline grinding, the experimental results show that after ultrasonic vibration grinding, the internal spline tooth profile deviation is reduced by 41.9%, and the tooth direction deviation is reduced by 44.1%, which provides a new processing method for the deformation recovery of internal splines after heat treatment.

Analysis and optimization of abrasive waterjet dressing parameters for surface texturing of diamond grinding wheels

With the development of ultra-precision machining technology, the grinding performance of diamond grinding wheels has put forward higher requirements. In this study, a new method of dressing diamond grinding wheels using abrasive waterjet (AWJ) technology is proposed to address the issues of workpiece damage and wheel clogging that occur when grinding difficult-to-machine materials with conventional diamond grinding wheels. The main process parameters were determined based on the theoretical model for dressing diamond grinding wheels using AWJ. The response surface methodology (RSM) and the backpropagation artificial neural network (BP-ANN) were employed to establish regression models between process parameters and microgroove characteristics. A comparison was performed to evaluate the prediction performance of both RSM and BP-ANN. The results indicated that both approaches BP-ANN and RSM are powerful tools for predicting microgroove characteristics. This work provides theoretical guidance for texturing diamond wheels surface.

Experimental investigation and numerical analysis of material removal efficiency using abrasive microaggregates in grinding processes of Ti6Al4V

Reducing plastic interactions between abrasive grains and the material being processed improves grinding efficiency and lowers energy consumption. Widening the cutting zone with abrasive grains enhances chip formation and reduces lateral material displacement. This can be achieved by using abrasive microaggregates.The paper presents an experimental analysis of grinding with modified wheels containing abrasive microaggregates. It examines how these microaggregates impact the grinding wheel's surface microgeometry and material removal efficiency. The study measured changes in the number, surface area, volume, and spacing of active contact areas on the grinding wheel active surface. A comparative analysis using the Shos indicator showed that abrasive microaggregates promote the formation of active areas with wide cutting edges perpendicular to the cutting direction.Finite element method simulations confirmed that abrasive microaggregates enhance material removal by widening the micro-cutting zone and increasing lateral resistance, which reduces the formation of flashes along the cutting path. The study also assessed how these surface features impact the roughness of the ground surface. A comparative analysis of roughness parameters showed a statistically significant reduction in surface, volume, hybrid, and functional parameters when using grinding wheels with abrasive microaggregates. This analysis was conducted using bootstrap statistical hypothesis tests.

ШЛИФОВАНИЕ ПОВЕРХНОСТИ ВОССТАНОВЛЕННЫХ ПОРОШКОВЫМИ ТРУДНООБРАБАТЫВАЕМЫМИ МАТЕРИАЛАМИ

The article discusses the use of impregnated abrasive wheels for grinding the surface of recovered hard-to-process powder materials. The paper investigates the formation of a rough surface during internal grinding of cylinders of marine engines after restoration to their original dimensions, with powder materials of grades PG-CP2, PG-10H-0.2 containing nickel, chromium, iron and other hard-to-work metals, which during the restoration process create a special protective metal layer on the surface of the cylinders, the processing of which is very difficult It's difficult. Therefore, the grinding of the internal surfaces of the restored cylinders of marine engines is a complex technological process that proceeds in strict compliance with all technological operations, in stages. According to the results of the study, the influence of the rotation speed of the workpiece on the roughness of the inner surface of the sleeve, accompanied by grinding with impregnated grinding wheels, was revealed. It has been experimentally confirmed that when treated with impregnated abrasive wheels, the roughness of the polished surface decreases by about 1.5-1.8 times.

No-impact trajectory design and fabrication of surface structured CBN grinding wheel by laser cladding remelting method

The structured grinding wheels have a specially designed macro or microstructure on the surface, with a relatively low average grinding force and temperature in the cutting zone and more space for chips and coolant. Most traditional grinding wheel fabrication methods, such as electroplating, sintering, and brazing, have the problems of poor abrasive grain holding strength, random abrasive distribution, or thermal deformation of the substrate. To address this, laser cladding remelting technology is introduced to fabricate the structured CBN grinding wheel. A no-impact trajectory was designed on the substrate of the grinding wheel, which can reduce the fluid friction in the channel and increase the fluid pressure at the outlet. The temperature and velocity fields of the grinding process were simulated to verify the feasibility of the designed structure theoretically. The optimal process parameters for the bonding among the metal bond, the abrasive grains, and the substrate were determined by orthogonal and full-scale factorial experiments. The chemical metallurgical reactions between CBN grain and metal bond, as well as between the metal bond and substrate, were formed, increasing the holding force of CBN grains. The method can realize the fabrication of high-strength and long-life structured grinding wheels with an orderly arrangement of abrasive grains. The micro-mechanism of fabrication was analyzed using element distribution measurement and XRD analysis.

High-speed grinding: from mechanism to machine tool

AbstractHigh-speed grinding (HSG) is an advanced technology for precision machining of difficult-to-cut materials in aerospace and other fields, which could solve surface burns, defects and improve surface integrity by increasing the linear speed of the grinding wheel. The advantages of HSG have been preliminarily confirmed and the equipment has been built for experimental research, which can achieve a high grinding speed of more than 300 m/s. However, it is not yet widely used in manufacturing due to the insufficient understanding on material removal mechanism and characteristics of HSG machine tool. To fill this gap, this paper provides a comprehensive overview of HSG technologies. A new direction for adding auxiliary process in HSG is proposed. Firstly, the combined influence law of strain hardening, strain rate intensification, and thermal softening effects on material removal mechanism was revealed, and models of material removal strain rate, grinding force and grinding temperature were summarized. Secondly, the constitutive models under high strain rate boundaries were summarized by considering various properties of material and grinding parameters. Thirdly, the change law of material removal mechanism of HSG was revealed when the thermodynamic boundary conditions changed, by introducing lubrication conditions such as minimum quantity lubrication (MQL), nano-lubricant minimum quantity lubrication (NMQL) and cryogenic air (CA). Finally, the mechanical and dynamic characteristics of the key components of HSG machine tool were summarized, including main body, grinding wheel, spindle and dynamic balance system. Based on the content summarized in this paper, the prospect of HSG is put forward. This study establishes a solid foundation for future developments in the field and points to promising directions for further exploration.

Report on Research for the Use and Popularization of Super Abrasive Grinding Wheels

Report on Research for the Use and Popularization of Super Abrasive Grinding Wheels

Chatter stability analysis for non-circular high-speed grinding process with dynamic force modelling

To avoid instability and resulting chatter during the non-circular grinding process, it is necessary to elucidate the potential occurrence of periodic chatter behavior when high-speed grinding loses stability and to define the stability boundary of the grinding system. Building upon an analysis of the geometric kinematic characteristics of non-circular profiled components, a dynamic grinding force model for non-circular high-speed grinding was derived by considering both the delay effect and the elastic yielding mechanism between the grinding wheel and workpiece. Then, A multi-factor coupled dynamic model of non-circular grinding was established. By employing a multi-scale approach, bifurcation analysis and classification of the instability process in the grinding system were conducted, using a typical non-circular profiled shaft component, such as a camshaft, for theoretical analysis and experimental validation. The research determined the stability boundary of the high-speed grinding process for non-circular profile components, validated the possibility of the existence of a conditionally stable chatter region in the non-circular high-speed grinding process, and identified differences in grinding chatter characteristics among different segments of the cam profile, with a greater propensity for chatter at the juncture of the cam fall and base circle.

Grit size effect on HydroFlex polishing dynamics and performance

Controllable, adaptable internal polishing is critical to metal additive manufactured (MAM) complex channels. Conventional fluid-based internal polishing methods are challenging to control the material removal, resulting in varied surface roughness (Sa) depending on channel length, aspect ratio (AR), and complexity. HydroFlex is an internal polishing method which drives a fixed-abrasive grinding wheel via a flexible spindle to navigate complex, high AR channels controllably and predictably removing material. Key to HydroFlex performance is the orbital motion of the grinding wheel governed by the hydrodynamic and cutting forces to achieve uniform polishing. Effect of grit size on orbital motion, and corresponding performance was experimentally evaluated. 46 µm, 76 µm, and 91 µm grit sizes were tested at a rotational speed of 50,000 rpm and a channel to wheel (C/W) ratio of 0.54 and orbital frequency and consistency, grinding force, Sa, material removal rate (MRR), and wheel wear were compared. Orbital frequency was found to directly correlate with increasing grit size and consistency of orbit shown to be highest at moderate grinding forces. Sa and MRR were inversely proportional with sub-micron roughness achieved at 0.15 g/min and 0.34 g/min corresponding to 2.2 µm Sa. Wheel wear was effected by grain pullout, attrition, and capping with all grit sizes experiencing similar wear. These findings suggest that orbital motion can be controlled through manipulation of wheel kinetics enabling precise control of grinding dynamics essential to adaptable performance in complex, non-uniform MAM channels.

Unveiling the temperature-dependent deformation mechanisms of single crystal gallium nitride in nanoscratching

The surface grinding process of single crystal gallium nitride (GaN) is intricate, and localized high temperature generated during interactions between the workpiece and the abrasives on grinding wheel is inevitable. Elevated temperatures significantly affect the deformation mechanisms of GaN, which remains inadequately elucidated. In this study, nanoscratching experiments were systematically conducted on the (0001) plane of GaN single crystal across a temperature range up to 500 ℃, and the resultant deformation patterns were thoroughly characterized. The results indicate that temperature elevation delays the brittle-to-ductile transitions in GaN and enhance its anisotropy. Additionally, GaN exhibits increased plasticity as temperature rises, leading to distinct scratch-induced subsurface deformation patterns at varying temperatures: at room temperature, the thickness of the subsurface damaged layer is primarily influenced by the penetration depth of cross slips, whereas at 500 ℃, basal slipping predominantly defines the thickness of the subsurface damaged layer. The plastic deformation patterns at both room temperature and 500 ℃ mainly involve phase transition, polycrystal formation, slips, stacking faults, dislocations and lattice distortions. The discrepancies in deformations at varying temperatures were thoroughly investigated by transmission electron microscopy and molecular dynamics simulations, and the underlying mechanisms were elucidated.

Active compliance control of grinding process for stripping enameled copper wire

The hairpin motor is among the motors used in eco-friendly automobiles. Unlike the random-winding method, this method features a square cross-sectional enamel coil formed into several hundred hairpins inserted into the stator. This offers an increased space factor, which leads to enhanced motor power. With the growing use of hairpin motors, there is an increasing demand for automated equipment in their production. With an aim to improve the manufacturing quality of hairpin motors, many countries are conducting research and development. The process of enamel removal is one of the key steps in hairpin-forming equipment and can significantly affect the performance of the motor. A precise machining process technology is required to improve the enamel removal process, achieve higher enamel removal rates, and reduce wire loss rates. Grinding is a technique used for enamel removal. In this study, an adaptive control algorithm was applied to the grinding process to enhance the enamel removal machining performance. During the machining process, the vertical position of the spindle was controlled to maintain a consistent machining depth for tracking the target grinding force. An experimental setup, which included a system for measuring the spindle torque to calculate the grinding force in real time, was created. To validate the performance of the adaptive control technology, experiments were conducted using this setup. Furthermore, experiments were conducted to observe the changes in the grinding force ratio based on the conditions of the grinding wheel. The correlation between the grinding force ratio and tool condition was analyzed, and based on this, the feasibility of assessing tool condition and determining the timing for tool replacement through real-time monitoring of the grinding force ratio was confirmed.

Hydrodynamic Flexible Spindle (HydroFlex) Polishing of turbine blade internal cooling channels for oxide removal

Internal cooling channels are essential to turbine blades for high efficiency power generation. Effective removal of aluminum oxide build-up in turbine blade cooling channels is of critical importance to refurbishment and prolonged service life of turbine blades. Conventional internal polishing processes, including abrasive flow machining, chemical polishing, and electrical discharge machining cannot effectively remove the oxide layer within the internal cooling channels due to the complex geometry with high aspect ratio and diameter variation and the electric insulation of the oxide layer. In this case study, we investigated the application of a novel hydrodynamic flexible-spindle (HydroFlex) polishing process to remove the oxide layer within the internal cooling channels of an Inconel 738 turbine blade that was taken out of serve due to oxide build-up. For a 350 mm long cooling channel featured with an inner diameter transition from ϕ4 mm to ϕ2.5 mm, within 12 min, at the grinding wheel rotational speed of 50,000 rpm and 30,000 rpm, HydroFlex was able to completely remove the 14.31 µm thick oxide layer off from the wall of the turbine blade internal cooling channel, improve the channel circularity by 54.7 %, and decrease the channel surface roughness by up to 64.3 %. The results demonstrated the effectiveness of HydroFlex in polishing complex internal cooling channels of turbine blades for oxide removal and potential blade service life extension.

Grinding of C/SiC ceramic matrix composites: Influence of grinding parameters on tool wear

C/SiC Ceramic Matrix Composites (CMCs) have been identified as a key material for improving high-speed braking systems and aerospace components as they offer low density, and high specific strength at high temperatures. Grinding is often used for the machining stage due to the high hardness, heterogeneity, and brittle nature of CMSs. Previous studies have explored the effect of grinding parameters, but most of them do not indicate whether they have used the same grinding wheel for all tests. In fact, there is limited understanding of how wear impacts process performance over the grinding wheel's lifespan. In this work, the effect of grinding wheel wear on cutting forces is addressed and grinding wheel topography is analyzed with the objective of identifying a parameter that allows to quantify grinding wheel wear in a non-destructive way. Results have shown that, after a short conditioning stage, cutting forces increase approximately linearly with the machined length. For the machining conditions analyzed, normal forces increase 200 % in the first machined meter (first stage), then rise 17 % per meter thereafter (second stage). Tangential forces rise 300 % in first meter and then climb 27 % per meter subsequently. In this second stage, force ratio approaches a constant value and the generation of flat surfaces on the diamond grains is the dominating wear mechanism. Under such conditions, 3D surface roughness parameters Sa, Sq, Spk and Sku have been proven to be useful for monitoring wheel wear.

Dressing Mechanism and Evaluations of Grinding Performance with Porous cBN Grinding Wheels

Cubic boron nitride (cBN) grinding wheels play a pivotal role in precision machining, serving as indispensable tools for achieving exceptional surface quality. Ensuring the sharpness of cBN grains and optimizing the grinding wheel's chip storage capacity are critical factors. This paper presents a study on the metal-bonded segments and single cBN grain samples using the vacuum sintering method. It investigates the impact of blasting parameters—specifically silicon carbide (SiC) abrasive size, blasting distance, and blasting time—on the erosive wear characteristics of both the metal bond and abrasive. The findings indicate that the abrasive size and blasting distance significantly affect the erosive wear performance of the metal bond. Following a comprehensive analysis of the material removal rate of the metal bond and the erosive wear condition of cBN grains, optimal parameters for the working layer are determined: a blasting distance of 60 mm, a blasting time of 15 s, and SiC particle size of 100#. Furthermore, an advanced simulation model investigates the dressing process of abrasive blasting, revealing that the metal bond effectively inhibits crack propagation within cBN abrasive grains, thereby enhancing fracture toughness and impact resistance. Additionally, a comparative analysis is conducted between the grinding performance of porous cBN grinding wheels and vitrified cBN grinding wheels. The results demonstrate that using porous cBN grinding wheels significantly reduces grinding force, temperature, and chip adhesion, thereby enhancing the surface quality of the workpiece.

A strategy of hob-grinding the cylindrical riblet surface for drag reduction by the grinding wheel with ordered abrasive pattern

A strategy of hob-grinding the cylindrical riblet surface for drag reduction by the grinding wheel with ordered abrasive pattern

Geometric Parameter Optimization for Axial Modification in Helical Gear Form Grinding

During the axial modification in helical gear form grinding, the contact line between the grinding wheel and the gear constantly changes, and the additional radial motion can cause a “tooth surface twist” phenomenon. An optimization method for tooth surface twist error was proposed to address this. Based on the gear meshing principles, a mathematical model for axial modification in form grinding was established to solve for the instantaneous contact lines at various positions on the actual modified tooth surface. By analyzing the influence of the grinding wheel installation angle on the axial modification contact line, an optimization model was constructed to reduce the twist of the transverse profile, reduce the twist of the flank profile, reduce the helix deviation, and improve the form grinding efficiency. The practical implications of this research are significant, as the Particle Swarm Optimization (PSO) algorithm was employed to optimize the form grinding parameters, leading to a method that effectively reduced tooth surface twist error and improved the form grinding accuracy of the modified tooth surface.