Effects Of Grinding Parameters Research Articles

An oil‐on‐water minimum quantity lubrication technology for high‐quality grinding of carbon fiber reinforced thermoplastic composites

AbstractCarbon fiber reinforced thermoplastic (CFRTP) composites, known for their excellent mechanical properties and environmental sustainability, are highly sought‐after in aerospace, energy, and many other fields. Grinding could be used to realize the high‐accuracy and low‐damage machining of CFRTP components. However, due to the temperature sensitivity and water absorption of CFRTP, dry and flood lubrication grinding could cause thermal damage and hygrothermal aging, respectively. In addition, these methods could lead to dust and excessive cutting fluids harmful to the environment. Addressing these bottlenecks, this study is the first to propose using oil‐on‐water minimum quantity lubrication (OoW‐MQL) to grind CFRTP. Experiments including various lubricating conditions and grinding parameters were performed to investigate the grinding performance. Experimental results showed that OoW‐MQL with the oil–water proportion of 1:1 outperformed the other lubricating conditions, achieving the best surface quality with the lowest grinding forces and temperatures. The optimal oil–water proportion remained almost unchanged under different grinding parameters. Furthermore, importance analysis using the extreme gradient boosting (XGBoost) algorithm demonstrated that oil–water proportion was the most critical factor affecting surface roughness. This study proves the feasibility of OoW‐MQL and provides technical guidance for high‐quality grinding of CFRTP.Highlights Oil‐on‐water minimum quantity lubrication (OoW‐MQL) was proposed to grind carbon fiber reinforced thermoplastic (CFRTP) composites. The experimental results of grinding forces, grinding temperatures, surface roughness and surface morphologies were analyzed, which proved that OoW‐MQL with oil–water proportion (1,1) had outstanding lubricating and cooling capability. The effect of grinding parameters on the optimal oil–water proportion was proved to be negligible through comparative tests under grinding parameters of high force and high temperature. Quantitative analysis using the extreme gradient boosting (XGBoost) algorithm identified the oil–water proportion as the most critical factor influencing surface roughness.

Effect of grinding parameters and coolants on grindability of Ti grade 9 alloy

For many years, surface roughness has drawn considerable attention, and it is a crucial design element in a variety of circumstances, including components sensitive to fatigue stresses, precision fittings, fastener holes, and aesthetic demands. Grinding the is best conventional machining process to achieve a better surface finish on a given component. Titanium 3Al-2.5 V or Ti grade 9 alloy is primarily utilized in the biomedical, aerospace, and automotive sectors. But because of its low heat conductivity, high chemical reactivity and rapid work hardening, this alloy is known as a difficult-to-cut material. In grinding, the abrasives have low thermal conductivity and small chip sizes, which in turn more heat to being focused in the cutting zone. This heat harms the surface of the workpiece. Therefore, it's crucial to regulate the quantity of heat that the workpiece receives.In this context, this work examines the surface quality of the Titanium 3Al-2.5 V alloy following surface grinding with an Al2O3 wheel under various grinding settings, including surface roughness (Ra), microhardness and material removal rate (MRR) from the workpiece. Techniques for delivering coolant conventionally (flood coolant), dry and using MQL were used and grinding performance were evaluated. The findings demonstrated that the Ra varied from 0.32 to 0.594 µm and hardness on the machine surface varied from 61.7 to 72 HRC. The MRR varied from 0.09 to 0.42 g/minute for the changes in depth of cut, table feed and coolants. Overall, the MQL has produced a good surface finish, high MRR and moderate hardness on the workpiece.

Grinding performance investigation of multidirectional CF/PEEK composites—A comparative with unidirectional CF/PEEK

AbstractTo distinguish the grinding performance of the multidirectional (MD) and unidirectional (UD) carbon fiber‐reinforced thermoplastic (CFRTP) composites, MD and UD carbon fiber‐reinforced poly‐etherether‐ketone (CF/PEEK) composites were employed in this study. Different ply stacking sequences and process parameters were set for grinding experiments. Subsequently, the surface morphologies and roughness were observed and measured. Experimental results indicated that the variations of grinding forces with grinding parameters of MD‐CF/PEEK and UD‐CF/PEEK were consistent. However, the heat transfer mechanism and the effects of grinding parameters on the maximum grinding temperatures were different between the two composites. The grinding forces and temperatures of MD‐CF/PEEK were slightly lower than UD‐CF/PEEK, and MD‐CF/PEEK reached better surface quality under the same parameters, indicating that the grinding performance of MD‐CF/PEEK was not the simple superposition of UD‐CF/PEEK. In addition, the chip formation and material removal mechanism of CF/PEEK were investigated. The grinding performance of MD‐CF/PEEK was primarily dependent on the θ elements of laminate while the grinding performance of UD‐CF/PEEK was closely related to the fiber orientation angles during grinding. This study established a more in‐depth understanding into the grinding performance of MD‐CF/PEEK and provided technical guidance for high‐quality grinding of CFRTP.Highlights The grinding performance of the multidirectional (MD) and unidirectional (UD) carbon fiber‐reinforced poly‐etherether‐ketone (CF/PEEK) is compared. The grinding forces and temperatures of MD‐CF/PEEK are slightly lower than that of UD‐CF/PEEK, and the MD‐CF/PEEK reach a better surface quality under the same grinding parameters. The grinding performance of MD‐CF/PEEK is primarily dependent on the θ elements of laminate, and the change of layering order is not a critical factor. The grinding performance of UD‐CF/PEEK is closely related to the fiber orientation angles during the grinding process. The surface quality of MD‐CFRTP can be effectively improved by reducing the grinding depth and feed speed, and increasing the grinding wheel speed.

Effect of grinding parameters on tooth surface waviness in continuous generating grinding for electric vehicle gears

Compared with traditional fuel vehicle gears, electric vehicle (EV) gears in its transmission system suffer harsher working conditions with stricter quality demands. Especially, regarding the need for low noise, as an indispensable acceptance indicator in the EV gear manufacturing industry, tooth surface waviness of EV gears has received great attention. However, in continuous generating grinding (CGG), many factors affect tooth surface waviness and tooth surface waviness is still highly unpredictable. Therefore, aiming at improving the gear noise of EVs, the effect of grinding parameters (grinding speed, feed rate, and normal stock) on tooth surface waviness is clarified with other interferences eliminated. Considering the characterization of both CGG and tooth surface geometry, a tooth surface evaluation approach for a single tooth surface was proposed to characterize the meso-scale surface geometric unevenness and directly reflect the processing quality. A tooth surface waviness model was proposed to study the effect of grinding parameters on tooth surface waviness. In the model, the spatiotemporal variability characteristics in CGG are considered while ignoring system vibration, machine tool errors, and so on. By simulating the evolution process of the remaining flank stock, tooth surface topography is modeled, from which simulated tooth surface waviness is extracted. To verify the proposed tooth surface waviness model, the gear grinding experiments were conducted. Under different grinding parameters, the simulated tooth surface waviness is consistent with the experimental results in the length-domain and frequency-domain. Furthermore, it was found that grinding parameters change the flank mean value, flank peak-to-peak value, and profile mean value in length-domain, and influence the distribution pattern and amplitude of the spectrums in the frequency-domain. Profile tooth surface waviness was found to be influenced by grinding parameters irregularly and flank tooth surface waviness was found to be more susceptible to the change of normal stock in the length-domain and frequency-domain.

Tactile Perception-Based Depth and Angle Control During Robot-Assisted Bent Bone Grinding

During bent bone grinding, the robot often needs to adjust its grinding depth and angle in real-time to ensure surgical quality. Optical- or vision-based navigation methods are no longer applicable due to the interference caused by splashing cooling water in the operating field. Inspired by orthopedic surgeons, this manuscript presents a tactile perception-based method to solve this problem. The effect of grinding parameters on the cutter's current and vibration is analyzed, and current and vibration signals are further processed to predict depth and angle. Depth and angle estimation models were calibrated on homogeneous artificial bone. Grinding control experiments were carried out on femur models, and the statistical mean and standard deviation results of the measured depth show that the accuracy of depth control can be further improved by adding angle estimation and proper adjustment when depth is indirectly estimated based on sensing signals. The proposed approach relies solely on the estimation of the relative position and posture between the tool and the bone surface and is expected to improve the safety of automatic grinding with orthopedic robots.

Effect of Grinding Parameters on Industrial Robot Grinding of CFRP and Defect Formation Mechanism

Effect of Grinding Parameters on Industrial Robot Grinding of CFRP and Defect Formation Mechanism

Hemispherical resonator with low subsurface damage machined by small ball-end fine diamond grinding wheel: A novel grinding technique

As for the ultra-precision grinding of the hemispherical fused silica resonator, due to the hard and brittle nature of fused silica, subsurface damage (SSD) is easily generated, which enormously influences the performance of such components. Hence, ultra-precision grinding experiments are carried out to investigate the surface/subsurface quality of the hemispherical resonator machined by the small ball-end fine diamond grinding wheel. The influence of grinding parameters on the surface roughness (SR) and SSD depth of fused silica samples is then analyzed. The experimental results indicate that the SR and SSD depth decreased with the increase of grinding speed and the decrease of feed rate and grinding depth. In addition, based on the material strain rate and the maximum undeformed chip thickness, the effect of grinding parameters on the subsurface damage mechanism of fused silica samples is analyzed. Furthermore, a multi-step ultra-precision grinding technique of the hemispherical resonator is proposed based on the interaction influence between grinding depth and feed rate. Finally, the hemispherical resonator is processed by the proposed grinding technique, and the SR is improved from 454.328 nm to 110.449 nm while the SSD depth is reduced by 94 % from 40 μm to 2.379 μm. The multi-step grinding technique proposed in this paper can guide the fabrication of the hemispherical resonator.

Computational Fluid Dynamics of Useful Grinding Fluid Flow and Sensitivity Analysis of Grinding Parameters

In the grinding process, a high speed rotating grinding wheel develops a stiff air barrier around it. This air barrier restricts the flow of incoming grinding fluid through a nozzle jet into the grinding zone, and this leads to a considerable amount of grinding fluid being wasted. An insufficient amount of grinding fluid from the nozzle jet not reaching the grinding wheel-workpiece contact zone will result in many defects in the workpiece as well as in the grinding wheel. In this paper, a unique method of air scraper is modelled and simulated in order to impinge the grinding fluid maximum through a thick boundary layer around the periphery of the rotating grinding wheel and the effect of grinding parameters are analyzed and Ugff rate equation established using Box Behnken Design method.

Modeling of material removal depth in robot abrasive belt grinding based on energy conversion

Accurate material removal is of great significance to ensure the machining accuracy of robot abrasive belt grinding (RABG). In this paper, a material removal depth (MRD) model for RABG of superalloy is proposed based on the energy conversion in grinding. Based on the characteristics of the shape and protrusion height distribution of grits, the energy conversion equation is established through the force analysis of the interference between grits and workpiece, and then the expression of material removal depth is derived by combining the Hertz elastic contact theory. In addition, in view of the change of belt coverage ratio caused by the structured belt wear, the expression of grit distribution density considering belt wear is obtained through the Archard wear model and applied to the MRD model. The MRD model is evaluated by the experiment, and the results show that the proposed model has good prediction ability. Furthermore, the effects of grinding parameters on MRD are analyzed, and the grinding parameters that take into account both the MRD and surface quality are discussed. This research provides a theoretical reference for material removal research in RABG.

Effects of Grinding Parameters on the Processing Temperature, Crack Propagation and Residual Stress in Silicon Nitride Ceramics

The surface/subsurface damage of engineering ceramics after machining has a great influence on the service performance of parts. In order to obtain a high grinding surface quality of engineering ceramics, and take silicon nitride ceramic as a research object, a series of grinding experiments were carried out. The effects of grinding parameters on longitudinal crack propagation depth and the surface residual stress of silicon nitride ceramics were analyzed by grinding experiments, and the residual stress at the location of crack propagation was obtained. The variation in the grinding temperature under different grinding parameters was explored. The influences of the grinding temperature on crack propagation depth and surface residual stress were clarified, the distribution of residual stress along the depth direction was discussed, and the relationship between the residual stress and crack propagation was revealed. The results show that the residual compressive stress on the surface of silicon nitride ceramics decreases with the increase in the depth of crack propagation and the degree of surface brittle spalling. The residual stress at the location of the crack propagation was residual tensile stress. The crack propagation depth increased with the increase in the residual tensile stress. The research provides a reference for the realization of high-quality surfaces in the grinding of silicon nitride ceramics.

Molecular dynamics simulation-based microstructure evolution and subsurface damage of Fe-Ni alloy grinding

PurposeMolecular dynamics is an emerging simulation technique in the field of machining in recent years. Many researchers have tried to simulate different processing methods of various materials with the theory of molecular dynamics (MD), and some preliminary conclusions have been obtained. However, the application of MD simulation is more limited compared with traditional finite element model (FEM) simulation technique due to the complex modeling approach and long computation time. Therefore, more studies on the MD simulations are required to provide a reliable theoretical basis for the nanoscale interpretation of grinding process. This study investigates the crystal structures, dislocations, force, temperature and subsurface damage (SSD) in the grinding of iron-nickel alloy using MD analysis.Design/methodology/approach In this study the simulation model is established on the basis of the workpiece and single cubic boron nitride (CBN) grit with embedded atom method and Morse potentials describing the forces and energies between different atoms. The effects of grinding parameters on the material microstructure are studied based on the simulation results.FindingsWhen CBN grit goes through one of the grains, the arrangement of atoms within the grain will be disordered, but other grains will not be easily deformed due to the protection of the grain boundaries. Higher grinding speed and larger cutting depth can cause greater impact of grit on the atoms, and more body-centered cubic (BCC) structures will be destroyed. The dislocations will appear in grain boundaries due to the rearrangement of atoms in grinding. The increase of grinding speed results in the more transformation from BCC to amorphous structures.Originality/valueThis study is aimed to study the grinding of Fe-Ni alloy (maraging steel) with single grit through MD simulation method, and to reveal the microstructure evolution within the affected range of SSD layer in the workpiece. The simulation model of polycrystalline structure of Fe-Ni maraging steel and grinding process of single CBN grit is constructed based on the Voronoi algorithm. The atomic accumulation, transformation of crystal structures, evolution of dislocations as well as the generation of SSD are discussed according to the simulation results.

Tangential Ultrasonic-Vibration Assisted Forming Grinding Gear: An Experimental Study.

This study used a forming grinding wheel to machine an involute spur gear with ultrasonic vibration applied to the gear in order to improve the gear processing technology and enhance the gear processing effect. Conventional grinding and ultrasonic vibration-assisted forming grinding gear (TUVA-FGG) tests were carried out. The effects of grinding parameters, such as spindle speed, feed rate, radial grinding depth, and ultrasonic amplitude, on grinding force, grinding temperature, residual stress, surface roughness, and surface morphology were analyzed. The TUVA-FGG significantly improved processing efficiency. With the increase in spindle speed, the maximum reductions in the normal and tangential grinding forces, grinding temperature, and surface roughness reached 33.6, 24.5, 23.9, and 21.6%, respectively. With the increase in feed rate, the respective maximum reductions were 21.4, 19.7, 20.3, and 16.1%. With the increase in radial grinding depth, these values attained 24.6, 20.3, 21.5, and 17.6%, respectively. Finally, with the increase in ultrasonic amplitude, these reductions reached 21.4, 19.7, 21.5, and 19.4%. The maximum residual compressive stress grew by 30.3, 27.5, 30.9, and 27.5% with the increase of wheel rotation speed, feed speed, radial grinding depth, and ultrasonic amplitude, respectively. TUVA-FGG changed the conventional continuous cutting mechanism between the abrasive grain and workpiece into intermittent cutting, reducing grinding forces, grinding temperature, and surface roughness. Moreover, it increased residual compressive stress and improved the micromorphology of the tooth surface, thus enhancing gear machining efficiency.

A grinding force predictive model and experimental validation for the laser-assisted grinding (LAG) process of zirconia ceramic

Laser-assisted grinding (LAG), as a potential machining method, is expected to achieve high-efficiency machining without any surface damage or sub-surface damage. However, grinding force tends to exert serious impact on the surface damage during LAG process. In this paper, a grinding force predictive model for the LAG process was established, which has taken the combined effects of temperature-dependent mechanical properties of the material, statuses of grit-material micro interaction, and stochastic shapes and random distributions of abrasive grits into consideration. This model also reveals the mechanism for the reduction of grinding force during LAG. In the meantime, the simulative grinding force distributions of workpiece surface with different laser powers were obtained. LAG experiments of zirconia ceramic were carried out to validate this model. It is found that the modelled forces are in good agreement with the measured forces and the error rates can be confined within 12 %. In addition, the effect of grinding parameters on grinding force has been investigated. It is demonstrated that the grinding force can be reduced by a certain percentage ranging from 29.4%–60.1% using the optimal machining parameters. Within a certain threshold, higher laser power can improve the surface integrity and decrease the depth of damage. This work is expected to provide significant guidance for promoting the development of the laser-assisted machining technologies.

Numerical modeling of material removal mechanism and surface topography for gear profile grinding

Gear profile grinding is more complex than surface grinding owing to the specific shape of the grinding wheel and geometric characteristics of the gear tooth, resulting in difficulties in modeling grinding components. Consequently, conventional grinding models tend to fail. To address this issue, a novel semi-analytical modeling method of the material removal mechanism and surface generation for gear profile grinding is proposed. Firstly, the grinding wheel model is represented by a multi-information fusion matrix that contains kinds of information about grinding grits. Compared with the traditional models that require several matrices to represent respective information, the proposed wheel model incorporates multi-dimensional information without extending the original matrix size and data length, which is more efficient. Then, a numerical model for the grinding process is developed by analyzing grit kinematics and grit-workpiece contact to reveal the material removal mechanism, and it is found that the cross-section shape of 3D cutting chips changes in the direction of the contact line. Furthermore, a surface topography model is established considering the specific pile-up effect. In this process, based on the length conservation of the tooth profile curve after straightening, the body Boolean operation is replaced by matrix calculation which reduces the dimension of data from 3D to 2D. Thus, computing time is reduced greatly, and this method does not require knowledge of the generation mechanism for tooth profile. Finally, experiments are conducted and the effects of grinding parameters on surface topography are investigated. The experimental results match well with model predictions, proving the model is effective. This work provides further understanding of the material removal mechanism for gear profile grinding. Meanwhile, it can also be extended and applied to other grinding processes for workpieces with complex geometry.

Experimental study of thermal behaviour of face grinding with alumina angular wheels considering the effect of wheel wear

The grinding industry is a high added-value manufacturing sector that is subject to ongoing improvements due to the increasing demands for productivity, accuracy and surface integrity. Although angular wheels are commonly used for face grinding in both automotive and aeronautical manufacturing, there is little information available regarding the specific details of applying this process. For this particular process, the effect of the wheel angle on process performance, the influence of kinematic parameters during the appearance of grinding burn or wheel wear is still unknown. This paper presents an experimental study of the thermal behaviour of face grinding with alumina angular wheels when considering the effect of wheel wear. The effect of grinding parameters has been examined using the concept of aggressiveness, which has been adapted to the kinematics of the process of face grinding with angular wheels. Special attention has been paid to the effect of the geometry of the wheel and to the dressing conditions. Through an extensive experimental study of power measurements and acid etching surface inspections complemented with temperature simulations, the behaviour of this process in response to grinding burn has been analysed in order to optimize the wheel duration towards grinding burn.

Effect of grinding parameters and microstructural features on surface integrity of ADI ground components

Effect of grinding parameters and microstructural features on surface integrity of ADI ground components

Effect of grinding parameters on surface quality in internal grinding of silicon nitride ceramics

Effect of grinding parameters on surface quality in internal grinding of silicon nitride ceramics

A novel energy partition model for belt grinding of Inconel 718

Analyzing and modelling energy partition is of great significance to provide an in-depth understanding of the grinding process that is essentially dynamic. However, research on dynamic energy partition in belt grinding is rather scarce, especially from the perspective of a comprehensive energy evaluation. Here, we propose a novel energy partition model for belt grinding of Inconel 718, on basis of heat transfer analysis, finite element method and optimization algorithm. The model takes into account varying grinding force, grinding temperature, material removal rate and the heat accumulation in grains. Through an iterative approach, the dynamic energy entering the workpiece, belt, chips and ambient during grinding process can be obtained. Grinding temperature and dynamic energy partition calculation are validated. Results show that the maximum error of the calculated temperature is within 8.4 %. Further, effects of grinding parameters, grinding temperature and abrasive grains on belt grinding energy partition are analyzed and discussed in detail.

Diamond wheel grinding characteristics of 3D orthogonal quartz fiber reinforced silica ceramic matrix composite

Fiber-reinforced silica ceramic matrix composites (SiO2f/SiO2) have gained extensive attention in recent years for its applications in aeronautics field such as radar radome and window. However, the machining properties and mechanism of the material remain unclear. The features and mechanical properties of the material itself have a significant influence on both its machining characteristics and surface integrity. Thus, a full-factor grinding experiment is conducted using a 3D orthogonal SiO2f/SiO2 aiming to obtain its machining characteristics. The effects of grinding parameters and tools on the grinding force, surface roughness, and material damage type are investigated using a dynamometer, Scanning Electron Microscope (SEM), and Acoustic Emission (AE) analysis. The AE frequency band is analyzed, and a semi-analytical force model is established to study the difference between a single grain and wheel grinding. It was found that the changes in surface roughness correlate with the changes in grinding force, with fiber fracture being the main reason behind the increase in grinding force. Finally, the material removal mechanism was studied based on the AE analysis. It was found that the removal mechanism is fiber fracture dominated with matrix crack and debonding, and the primary sources of energy consumption are fiber fracture and friction.

Effect of Grinding Parameters on the Hardness Penetration Depth of the Steel GCr15 in Internal Grind Hardening Process

This paper discusses the effects of the depth of cut (ap ), the workpiece speed (vw ) and the grinding wheel speed (vs ) on the structure and hardness of the grind hardening layer on the steel GCr15. It was found that the completely hardened zone of the internal grind-hardened layer on the steel GCr15 mainly contains needle-shaped martensite and a very low amount of carbides and retained austenite. The grinding parameters have no significant effect on the martensite microstructure and hardness of the high-hardness zone in the internal grind-hardening process. An increase of the depth of cut and the grinding wheel speed or a decrease of the workpiece speed, leads to a thicker grind-hardening layer. From the viewpoint of increasing the hardness penetration depth, a larger the depth of cut and the grinding wheel speed and a smaller the workpiece speed should be selected, under the internal grind-hardening experimental conditions.