Increase Of Grinding Depth Research Articles

Removal mechanism of double-diamond-abrasive-grinding GaN single crystals under graphene lubrication

Gallium nitride (GaN) is an advanced material used to manufacture chip wafers and high-power devices. Recently, grinding processing, has been applied in the fields of machinery manufacturing, aerospace, and medical devices as a highly efficient machining method. An in-depth understanding of the material removal mechanism produced by the double-grinding processes can provide guidance for the design of GaN-based nanodevices. Herein, molecular dynamics simulations were used to investigate the mechanism of removal of double-diamond-abrasive-grinding gallium nitride crystals under graphene lubrication, and a systematic study was performed to investigate the involved surface morphology, grinding force, stress distribution, and subsurface damage behavior. Results reveal that graphene can substantially enhance the wear resistance of GaN substrates by reducing surface wear, atomic displacement., potential energy, and subsurface damage, thereby playing a protective role toward the substrate. As the grinding depth increases, the grinding force and subsurface damage depth also increase. Furthermore, the effects of abrasive grain spacing on subsurface damage depth and phase change atoms were analyzed and found to have limited influence on material removal efficiency. These results deepen our understanding of material removal and protection mechanisms relative to substrates resulting from double-grinding processes as well as offer valuable insights for the rational design of abrasive wheels.

Research on the surface modification and microstructure evolution during gear profile grinding based on cellular automaton

The matrix structure of high-strength gears mainly comprises martensite with high stacking fault energy. The dominant mechanism of microstructure evolution in the surface layer during profile grinding is continuous dynamic recrystallization. However, the understanding of continuous dynamic recrystallization structure evolution during gear profile grinding remains limited. In this study, a predictive model based on cellular automaton for martensite structure evolution during gear profile grinding is proposed. Coupled with the finite element method, the microstructure evolution prediction of high-strength steel gears in profile grinding is conducted. The proposed model demonstrates good consistency with experimental data in calculating the proportion of low angle grain boundaries during grinding process. By combining experimental and theoretical prediction results, the mechanism of the influence of grinding depth on grain refinement in surface layer during gear profile grinding is elucidated. The dislocation density increases with the increase of grinding depth, leading to the generation and transformation of more subgrains. By analyzing the grain size and the proportion of subgrain boundaries, an optimal grinding depth threshold under dry grinding conditions is determined. This study provides valuable insights into the continuous dynamic recrystallization structure evolution during gear profile grinding process.

Numerical Investigation on the Effects of Grain Size and Grinding Depth on Nano-Grinding of Cadmium Telluride Using Molecular Dynamics Simulation.

Cadmium telluride (CdTe) is known as an important semiconductor material with favorable physical properties. However, as a soft-brittle material, the fabrication of high-quality surfaces on CdTe is quite challenging. To improve the fundamental understanding of the nanoscale deformation mechanisms of CdTe, in this paper, MD simulation was performed to explore the nano-grinding process of CdTe with consideration of the effects of grain size and grinding depth. The simulation results indicate that during nano-grinding, the dominant grinding mechanism could switch from elastic deformation to ploughing, and then cutting as the grinding depth increases. It was observed that the critical relative grain sharpness (RGS) for the transition from ploughing to cutting is greatly influenced by the grain size. Furthermore, as the grinding depth increases, the dominant subsurface damage mechanism could switch from surface friction into slip motion along the <110> directions. Meanwhile, as the grain size increases, less friction-induced damage is generated in the subsurface workpiece, and more dislocations are formed near the machined groove. Moreover, regardless of the grain size, it was observed that the generation of dislocation is more apparent as the dominant grinding mechanism becomes ploughing and cutting.

Study on Grinding Force of Two-Dimensional Ultrasonic Vibration Grinding 2.5D-C/SiC Composite Material

The grinding force is an important index during the grinding process, which affects the surface quality and other aspects after machining. However, the research on the grinding force of ceramic matrix composites assisted by two-dimensional ultrasonic vibration-assisted grinding is very weak. In this paper, the impact of the relationship between the critical cutting depth and the maximum undeformed chip thickness on the removal mode of ceramic matrix composites was analyzed. On this basis, the grinding force model of two-dimensional ultrasonic vibration-assisted grinding were developed for ductile removal and brittle removal, respectively. Finally, the correctness of the model was verified, and the impact of grinding parameters on the grinding force was analyzed. The experimental results show that compared with the conventional grinding force, the two-dimensional ultrasonic vibration assisted grinding force decreases obviously. When the feed rate and grinding depth increase, the grinding force increases. When the grinding velocity and ultrasonic amplitude increase, the grinding force decreases. Compared with the experimental value, the average relative error of normal grinding force is 8.49%, and the average relative error of tangential grinding force is 13.59%. The experimental and theoretical values of the grinding force have a good fitting relationship.

Experimental study on residual stress in high-speed grinding of noncircular equidistant profile

To explore the formation mechanism of residual stress in the high-speed grinding of noncircular equidistant profiles, orthogonal experiments of three grinding parameters—the grinding wheel speed, workpiece speed, and grinding depth—were designed. A ceramic bond CBN grinding wheel was used for the high-speed grinding of noncircular equidistant profile by the X-C axis linkage. The effects of the grinding parameters on the grinding temperature, surface roughness, and residual stress were analyzed. The results show that with the increase of grinding wheel speed, the grinding temperature and residual stress increase, and the surface roughness decreases. With the increase of workpiece speed, the grinding temperature and residual stress decrease, and the surface roughness increases. With the increase of grinding depth, the grinding temperature, residual stress, and surface roughness increase. Besides, the grinding depth has the greatest influence on the residual stress, followed by the grinding wheel speed and workpiece speed.

Residual stress evolution and surface morphology in grinding of hardened steel following carburizing and quenching processes

AbstractIn this paper, the residual stress evolution and surface morphology of quenched 20Cr2Ni4A steel after surface grinding with alumina grinding wheel was investigated. The initial compressive residual stress in the surface layer evolved into tensile stress after grinding. Since thermal stress was the dominated factor, the effect of grinding speed and grinding depth showed significant effects on the level of residual stress. The tensile stress on the ground surface increased by more than 50 % when grinding speed increased from 26 m/s to 34 m/s at the feed speed of 0.19 m/s to 0.26 m/s. The increase of grinding depth from 0.02 mm to 0.03 mm resulted in the increase rate of tensile stress varying between 54 % and 85 % at specific feed speed and grinding speed. Due to the extrusion and cutting of abrasive particles, plastic deformation and grooves were found on the machined surface. The influence of grinding heat and grinding force caused a plastic deformation layer and grinding burn layer within 20 μm.

Experimental investigation on the effects of machining parameters on surface integrity in form grinding of rail material

Rail grinding is an essential measure for the maintenance of railway infrastructure, and the machined surface integrity of rail material plays a crucial role in ensuring the safety, stability and service performance of the railway network. In this paper, an electroplated diamond grinding wheel was employed to re-profile the rail surface. Meanwhile, single-factor experiments on the form grinding of rail material were designed and carried out by virtue of the self-developed rail grinding platform under dry grinding condition based on proper machining parameters. The effects of machining parameters on the surface roughness, subsurface micro-hardness, plastic deformation, and surface morphology were investigated, respectively. The experimental results revealed that the surface roughness and subsurface micro-hardness increase with the increase of feed speed and grinding depth, while decrease with the increase of wheel peripheral speed. The thickness of subsurface plastic deformation layer and the degree of plastic flow increase with the increase of grinding depth, and the thickness of subsurface plastic deformation layer ranges from 7 μm to 14 μm with the change of grinding depth.

Surface modification of ultrahigh strength 300M steel under supercritical carbon dioxide (scCO2)-assisted grinding process

300M steel has been widely utilized in the manufacturing processes of functional parts served in harsh environments. The properties of the parts’ surface layer induced by the grinding process are of great importance for the service performance, which can be determined by the input parameters of processing. This paper carried out evaluation of surface modification of 300M steel material under the scCO2-assisted grinding process. To further enhance the understanding of this processing design, the generation of surface modification with dry and flood techniques were also compared. The surface morphology, surface roughness, microstructure evolution, work hardening and surface residual stresses were recorded. The mechanism of grain refinement and the substructure of the martensite lath has been revealed. It was found that the scCO2-assisted grinding processes are responsible for smoother surface profile compared to the dry and flood techniques. Meanwhile, the machined surface roughness was maintained at a stable lower level as the grinding depth increases, proving the great superiority of scCO2 medium for improving the productivity and process sustainability. The grains in the superficial layer have been noticeably refined after grinding operation while it presents deeper refinement with scCO2-assisted grinding process. Meanwhile, nanocrystalline and carbide precipitation were clearly found on the refined layer with scCO2 medium, the crystal defects are mainly the combination of dislocation tangles (DTs), dislocation walls (DWs) and dislocation cells (DCs), and the stacking fault was observed to be the substructure for the lath martensite except the dislocation with TEM analysis. The designed scCO2-assisted grinding contributes to higher work hardening and compressive stresses compared to dry and flood methods.

Grinding temperature prediction model of high-volume fraction SiCp/Al composite

Grinding is the main processing technique for particle-reinforced composites, in which grinding force and temperature are significant for investigating the removal mechanism and surface properties. In this study, a grinding force prediction model is established based on the response surface methodology. The energy density of surface heat source in the grinding area is calculated by combining the contact area between the grinding wheel and workpiece. Based on the integration algorithm in time and space, a theoretical ideal grinding temperature prediction model is deduced. The grinding heat energy transfer coefficient is defined as the percentage of heat energy, which is transferred from the grinding heat energy to the workpiece. According to the experimental and ideal theoretical highest grinding temperatures, a prediction model of the heat energy transfer coefficient is established, and the modified theoretical highest grinding temperature prediction model is obtained. Furthermore, a finite element model of SiCp/Al composite in grinding is established. The highest grinding temperature in the finite element model is consistent with the modified theoretical highest grinding temperature, and the grinding temperature field is analysed. The highest grinding temperature increases as the wheel speed and grinding depth increase, while it decreases as table speed increases, which differs from that of some common materials. Thus, the grinding temperature prediction model provides an important reference for the study of removal mechanism and surface properties of SiCp/Al composite.

Experimental Analysis of Process Parameter Effects on Vibrations in the High-Speed Grinding of a Camshaft

The capacity to minimize vibrations in grinding by the selection of appropriate process parameters is a significant benefit in the process optimization of cam grinding. This paper presents survey methods to characterize and quantify the vibrations and waviness in a camshaft grinding application. First, a modal analysis was conducted to study the dynamic characteristic of a camshaft grinding machine. Then, developed methods were applied to study the influences of various parameters on vibrations in the high-speed grinding of a camshaft. Furthermore, the influence of each grinding process condition on surface waviness in high-speed camshaft grinding was studied. The results show that the vibrations and the surface waviness change with the increase of grinding depth, and an appropriate grinding wheel speed combined with a workpiece speed has, for most grinding conditions, a reducing effect on vibration magnitudes and waviness. Finally, the specific indications about the optimal grinding process parameters in terms of dynamic characteristics of the grinding machine were given, and the speed ratio=1.2 is a novel choice.

Study on grinding damage of high chromium alloy based on molecular dynamics

The new cast high chromium alloy is the conventional material of the nuclear main pump thrust-bearing with good wear and corrosion resistance. According to the structural characteristics of high chromium alloy, the simulation model and the coupling potential function were constructed to study the grinding damage layer using molecular dynamics method. The simulation results show that the crystal lattice distortion caused by carbon atoms in the formation of interstitial solid solution leads to the occurrence of amorphous structure after full relaxation. The break and recombination of metal bond and non-metal bond between atoms in the alloy result in the occurrence of damaged layer under grinding. And the bond angles between the atoms in the damage layer are less than that in the alloy matrix. The damage layer is mainly composed of atoms in front of the abrasive particle and the atoms of extrusion deformation in the bottom. Moreover, with the increase of grinding depth, the cutting force and the damage layer thickness increase. The study is conducive to understand the damage formation mechanism of high-chromium alloy materials in micro-nano processing, and provides a theoretical reference value for the actual processing.

Residual stress model of pre-stressed dry grinding considering coupling of thermal, stress, and phase transformation

Pre-stressed dry grinding can result in a hardened layer on the part surface while the surface residual stress is controlled. Considering the factors of the thermal field, pre-stress, and microstructural transformation, a proximate model of surface residual stress for pre-stressed dry grinding is established using the ANSYS finite element simulation method and verified through experiment. The variation laws and mechanisms of the residual stress along with the grinding parameters are revealed. Under the comprehensive effect of pre-stress and phase transformation, the residual stress of pre-stressed dry grinding is revealed mainly as compressive stress. This increases as the pre-stress and grinding depth increase. Under the coupling effect, pre-stress has larger influence on the residual stress than the grinding depth. The model can analyze and predict the residual stress of pre-stressed dry grinding in general.

System design and experimental research on ultrasonic assisted elliptical vibration grinding of Nano-ZrO2 ceramics

Aiming at the low toughness, high hardness and difficult machining of hard and brittle materials such as Nano-ZrO2 ceramics, a new type of ultrasonic assisted elliptical vibration grinding (UAEVG) system was designed to improve its machinability and grinding quality. The overall frequency equation of the ultrasonic grinding cup-shaped tool transformer (UGCTT) was derived by the integrated nonresonant design method and the length of the conical horn was optimized. The trajectory of abrasive particles was simulated by finite element software and verified by ultrasonic resonance test. Finally, through the experiment of UAEVG Nano-ZrO2 ceramics, the effects of UAEVG method on its surface morphology, roughness and residual stress were explored. The results showed that when the length of the horn was 65 mm after optimization, the transformer had good vibration mode. Simulation and ultrasonic resonance test results showed that the abrasive particles periodically moved in an elliptical shape in the longitudinal radial plane, and the radial and longitudinal amplitude were AR = 7.5 μm and AL = 3.1 μm. The grinding experiments of Nano-ZrO2 ceramics showed that UAEVG could change the grinding mechanism of conventional grinding (CG), reduce the generation of grinding debris and material fracture. When the grinding depth was increased, the plastic processing ratio of the material under UAEVG was significantly larger than that of CG, which could form a better surface topography. The surface roughness increased with the increase of the grinding depth and feed rate, and the surface compressive stress decreased with the increase of grinding depth. UAEVG could reduce the surface roughness by about 30% and increase the residual compressive stress by about 20% compared with CG, which could achieve better grinding surface quality. Therefore, it can be concluded that UAEVG could expand the plastic processing domain, improve the surface integrity and fatigue strength of Nano-ZrO2 ceramics to some extent.

An analytical method for surface roughness prediction in precision grinding of screw rotors

In the process of grinding, rubbing, plowing, and cutting occur successively between abrasive grains and workpiece material as the grinding depth increases. In precision grinding of the screw rotor, small grinding depth is generally introduced, which usually results in plowing. Therefore, it is essential to predict the surface roughness caused by plowing in order to make the process controllable. In this paper, an analytical method for predicting tooth surface roughness of the screw rotor in precision grinding has been proposed. This method takes the following factors into consideration, i.e., distribution law of the grain protrusion heights, variation of grinding depth, velocities and diameters of the screw rotor and grinding wheel at different contact points, and the dressing parameters of grinding wheel. A trajectory projection method has been employed to determine the groove depth and distribution left by the abrasive grains. With the proposed model, the distribution of roughness over the screw rotor tooth surface can be calculated. Verification experiments were conducted with several screw motors produced and surface roughness measured. The comparison results reveal a good agreement between predicted results and experimental results, showing the effectiveness of the proposed method. This study could shed light on the plowing phenomena in precision grinding and could provide great potential in achieving an effective control of the surface roughness.

Study on grinding damage of high chromium alloy based on molecular dynamics

The new cast high chromium alloy is the conventional material of the nuclear main pump thrust-bearing with good wear and corrosion resistance. According to the structural characteristics of high chromium alloy, the simulation model and the coupling potential function were constructed to study the grinding damage layer using molecular dynamics method. The simulation results show that the crystal lattice distortion caused by carbon atoms in the formation of interstitial solid solution leads to the occurrence of amorphous structure after full relaxation. The break and recombination of metal bond and non-metal bond between atoms in the alloy result in the occurrence of damaged layer under grinding. And the bond angles between the atoms in the damage layer are less than that in the alloy matrix. The damage layer is mainly composed of atoms in front of the abrasive particle and the atoms of extrusion deformation in the bottom. Moreover, with the increase of grinding depth, the cutting force and the damage layer thickness increase. The study is conducive to understand the damage formation mechanism of high-chromium alloy materials in micro-nano processing, and provides a theoretical reference value for the actual processing.

Effect of grinding depth on surface topography by considering vibrations and a force prediction model

Little consideration has been given to vibrations when the effect of grinding process parameters on the surface morphology is studied. Taking a grinding force as the intermediate variable, influences of grinding depths on the surface topography are investigated with considering vibrations in this paper. Firstly, a novel grinding force prediction model is proposed through amending the Malkin model by integrating with contact arc length and abrasive grain contact angle. Secondly, vibrations of the feed platform and the grinding wheel shaft are analysed. Vibration displacement in the x-direction of wheel axis remains substantially between 140-150 nm, while in the y-direction, it increases with the grinding depth. Finally, three-dimensional surface topographies with different grinding depths are investigated. It is observed that the pronounced defects and a coarse texture are generated as the grinding depth increases. Parameters like Sa, Sq, Sku, Ssk are more suitable to represent the real grinding quality of workpiece surface.

Effect of grinding depth on surface topography by considering vibrations and a force prediction model

Little consideration has been given to vibrations when the effect of grinding process parameters on the surface morphology is studied. Taking a grinding force as the intermediate variable, influences of grinding depths on the surface topography are investigated with considering vibrations in this paper. Firstly, a novel grinding force prediction model is proposed through amending the Malkin model by integrating with contact arc length and abrasive grain contact angle. Secondly, vibrations of the feed platform and the grinding wheel shaft are analysed. Vibration displacement in the x-direction of wheel axis remains substantially between 140-150 nm, while in the y-direction, it increases with the grinding depth. Finally, three-dimensional surface topographies with different grinding depths are investigated. It is observed that the pronounced defects and a coarse texture are generated as the grinding depth increases. Parameters like Sa, Sq, Sku, Ssk are more suitable to represent the real grinding quality of workpiece surface.

An Investigation of Surface Roughness in Ultrasonic Assisted Dry Grinding of 12Cr2Ni4A with Large Diameter Grinding Wheel

Ultrasonic assisted dry grinding (UADG) is a novel green manufacturing technology for decreasing the negative environment impact of cutting fluids and improving the surface characteristics. In this study, the influences of the ultrasonic amplitude, grinding depth and grinding velocity on the surface roughness in ultrasonic assisted dry grinding of 12Cr2Ni4A with a large CBN grinding wheel were investigated. Due to the Poisson effect, the ultrasonic assisted dry grinding using a large diameter grinding wheel is the combination of axial ultrasonic assisted grinding and radial ultrasonic assisted grinding. The results indicated that the main axial ultrasonic component tended to smooth the surface topography by increasing the interaction overlap of the adjacent cutting traces, but it would result in more side flow/ploughing on the surface at a larger ultrasonic amplitude; the radial ultrasonic component exerted a function on the increase of the surface roughness through deepening the individual grinding trajectories. Thus, the surface roughness decreased first and then increased with the increase of grinding depth due to the combined contribution of axial and radial vibrations. However, the improving effect of ultrasonic vibration on the surface roughness gradually weakened with the increase of grinding velocity. Under proper operating parameters, surface roughness obtained in ultrasonic assisted dry grinding can be reduced up to 30% compared with that of common dry grinding.

The Study on Grinding Ratio in Form Grinding with White Fused Alumina (WA) Grinding Wheels

The study is carried out based on an experiment of form grinding spur rack with white fused alumina (WA) grinding wheels. In the experiment, SOV-3020A type tri-axial image mapper is utilized to measure the profile of the tooth space in the rack, and the curve equations between the sectional area of the tooth space and the tooth sequence under different grinding depths are established by nonlinear curve regress using software of origin8.0. Then, it deduces the prediction equations for current grinding ratio and cumulative grinding ratio under different grinding depths. The result shows that the grinding ratio is exponential decline relationship with the increase of the number of the tooth to be ground under the same grinding depth, and the decline speed is fast in the initial stage. With the increase of grinding depth, the grinding ratio increases gradually. The cumulative grinding ratio is about twice as high as the current grinding ratio. Thus, large grinding depth is generally used in rough grinding to improve grinding efficiency.

A study of grinding forces of SiCp/Al composites

In this study, the grinding experiments were conducted on SiC particle-reinforced aluminum matrix (SiCp/Al) composites under wet, dry, cryogenic, and ELID grinding conditions, and the effects of grinding depth and table speed on grinding forces and grinding force ratio were investigated. The experimental results showed that both the normal and tangential grinding forces of SiCp/Al composites increased evidently with the increasing of the grinding depth and table speed under the four grinding conditions. And the grinding forces under the cryogenic condition were the largest, the grinding forces under the dry condition were the second, and the grinding forces under the wet condition were the minimum. Additionally, the grinding force ratio values decreased with the increase of grinding depth under the wet and dry conditions, while the grinding force ratio values increased slightly with the increase of the grinding depth under the cryogenic and ELID grinding conditions. The grinding force ratio was minimum under ELID grinding condition.