Ground Surface Quality Research Articles

Study on ultrasonic elliptical vibration-assisted grinding mechanism and surface quality of C/SiC composite material

2.5D C/SiC composites have excellent mechanical properties and broad application prospects in the aerospace field. This study investigates the ultrasonic elliptical vibration-assisted grinding mechanism of 2.5D C/SiC composites in different structural directions. A surface roughness prediction model considering abrasive grain protrusion height, brittle-plastic transition of materials and the influence of ultrasonic vibration is established. Experimental results show that material removal involves matrix and fiber fracture, fiber pullout and interface debonding. Ultrasonic vibration causes intermittent cutting, producing finer chip particles and numerous cross microgrooves, reducing subsurface damage. The roughness prediction model is in good agreement with the experimental trend. When the grinding speed is increased from 1 m/s to 8.9 m/s, the surface roughness Ra is reduced by 30.1 %. When the feed speed is increased from 50 mm/min to 650 mm/min, the surface roughness Ra is increased by 47.6 %. When the grinding depth is increased from 0.01 mm to 0.04 mm, the surface roughness Ra is increased by 53.2 %. This study provides a reference for efficient and low-damage processing of fiber-reinforced ceramic matrix composites.

Surface roughness prediction model and surface topography analysis of 2.5D-Cf/SiC in two-dimensional ultrasonic assisted grinding based on GA-BP neural network

Because of the anisotropy and non-uniformity, the grinding surface quality of Cf/SiC composites is difficult to be accurately predicted. The quality of the surface directly determines the assembly accuracy. To better predict the surface quality of 2.5D-Cf/SiC composites, the BP neural network was optimized by genetic algorithm (GA), and the surface roughness prediction model of fiber orientation, ultrasonic amplitude, and machining parameters was established. The empirical formula prediction model of surface roughness was established by the method of multiple linear regression analysis. The results show that the prediction accuracy of GA optimized BP neural network is the best, followed by the empirical formula, and the prediction effect of the BP neural network is the worst. The average absolute percentage error of these three models is 10.045%, 16.912% and 26.6245% respectively. The kinematic models of conventional and two-dimensional ultrasonic-assisted grinding of single particles were established respectively. Based on the kinematic model, the reasons for the reduction of surface roughness by 2D ultrasonic-assisted grinding are explained. According to the orthogonal test results, the surface roughness decreases the most when vs is 0.66m/s, vw is 100mm/min, ap is 150μm along the fiber orientation of 0°, and the maximum percentage of reduction is 53.18%. Increasing the linear speed, reducing the feed speed, reducing the grinding depth, and applying ultrasound can reduce the extrusion pressure along the axis of 0° fiber, and then reduce the length and depth of cracks and thus reduce the surface defects. The axial shear force of the 90° oriented abrasive particles on the fiber is reduced, thus reducing the surface damage caused by torsional deformation. Reduce 3D surface profile and improve surface quality. The maximum percentage reduction of each parameter index is as follows: root mean square height decreased by 28.8%, skew decreased by 88.61%, kurtosis decreased by 48.97%, maximum crest height decreased by 48.55%, maximum sag height decreased by 40.09%, maximum height decreased by 43.93%, and arithmetic mean height decreased by 26.06%.

Wear behavior of white alumina and seeded gel abrasive wheels in ultrasonic vibration-assisted grinding of nickel-based single-crystal alloy

This study investigated the tool wear behavior of white alumina (WA) and seeded gel (SG) abrasive wheels in the ultrasonic vibration-assisted creep feed grinding (UVACFG) of nickel-based single-crystal alloy. The abrasive wheel wear characteristics were examined, and their effects on the grinding force, temperature, and surface quality were evaluated. Finally, the wheel wear mechanism in the UVACFG was discussed by analyzing the intermittent cutting behavior and wear patterns of a single grain. Experimental results indicated that the workpiece material adhesion and pore-clogging were the main wear patterns of abrasive wheels without ultrasonic vibration. In contrast, these were adequately mitigated after introducing ultrasonic vibration, and the main wear pattern for both wheels became the grain fracture. The WA wheel in the UVACFG experienced reduced radial wear by around 60.7 % in the initial wear state, 40.2 % in the stable wear state, and 25.3 % in the rapid wear stage, respectively, compared to the conventional grinding (CG). The intermittent cutting behavior of SG grains caused by high-frequency vibration promoted the micro-fracture capacity and ensured the coolant entered the grinding zone sufficiently, which reduced the grinding force and temperature by up to 63.2 % and 46.7 %, respectively, and meanwhile introduced the defects of high bulges and slight plastic deformation on the workpiece surface.

Analysis of the Surface Quality and Temperature in Grinding of Acrylic-Based Resin

Analysis of the Surface Quality and Temperature in Grinding of Acrylic-Based Resin

Effects of grinding mode on grinding performance of anisotropic CF/PEEK composites

AbstractGrinding could be used to enhance accuracy and quality of carbon fiber‐reinforced poly‐ether‐ether‐ketone (CF/PEEK) composites. However, the grinding mode, namely up‐grinding (UG) or down‐grinding (DG), is usually neglected while unbefitting grinding mode choice may cause inferior surface quality. To investigate effects of grinding modes on grinding performance of anisotropic CF/PEEK, grinding experiments in UG and DG were carried out under different fiber orientation angles θ. Experimental results indicated that maximum grinding temperatures and normal grinding forces in UG were lower than DG regardless of the abrasive grit sizes. Material removal mechanisms of CF/PEEK affected by grinding mode were revealed by analyzing morphologies of surface, chip and grinding wheel. When θ = 0°, the dominant mechanisms in DG were extrusion fracture and fiber deformation, while they were interface shear debonding and bending fracture in UG. When θ = 90°, the dominant mechanisms in DG included interface layer separation and bending fracture, while they were shear and extrusion fracture of well‐supported fibers in UG. Thus, UG was more favorable for material removal, obtaining lower surface roughness values, fewer machining defects and less wheel wear than DG. This study will provide technical guidance for high‐quality grinding of carbon fiber‐reinforced thermoplastic composites.Highlights The effects of grinding modes (DG and UG) on the grinding performance of anisotropic CF/PEEK composites were investigated. Material removal mechanisms of CF/PEEK affected by grinding mode were revealed under different fiber orientation angles. The maximum grinding temperatures and normal grinding forces in UG were lower than DG. UG was more favorable for material removal in grinding, and could produce better ground surface quality than DG.

Study on the grinding surface quality of CNTs/2009AL composite material based on minimum quantity lubrication

Carbon nanotube aluminum matrix (CNTs/AL) composites are ideal lightweight and high-strength materials due to their excellent properties. However, the research on CNTs/AL composites only stays in the simulation and preparation stages, and no grinding research has been carried out. Revealing the grinding mechanism of CNTs/AL composites has far-reaching significance for the development of high-end equipment industries such as aerospace. Taking CNTs/2009AL composites as the research object, a minimum quantity lubrication (MQL) flat grinding platform was built for comparing the surface quality and defects of dry grinding and MQL grinding. The experimental results show that grinding wheel velocity was the grinding parameter that had the greatest influence on surface roughness in dry grinding and MQL grinding. The subsurface defects of dry grinding mainly included microcracks, burrs, pits, coatings, cavities, etc., and the rebound phenomenon of agglomerated carbon nanotubes. The subsurface defects of MQL grinding were only burrs and pits. The surface coating phenomenon of dry grinding increased with the increase in grinding wheel velocity, and the surface quality was improved. MQL grinding could significantly reduce grinding heat, reduce friction, and make the machined surface smoother. In dry grinding and MQL grinding, the subsurface damage depth decreased obviously with the increase in grinding wheel velocity. When the grinding wheel velocity was 30 m/s, the minimum subsurface damage depth of dry grinding and MQL grinding was 40.091 and 26.906 μm, respectively. Mastering the grinding mechanism of grinding CNTs/AL composites and the influence of grinding parameters on surface quality provides a basis for the selection of parameters and methods in grinding in industry. MQL grinding of CNTs/AL composites reduces the formation of many surface defects and improves the surface quality of the workpiece. It is an efficient, clean, and environmentally friendly processing method.

Pre-control of grinding surface quality by data-driven: a review

Pre-control of grinding surface quality by data-driven: a review

Influence mechanism of grinding surface quality of 20CrMnTi steel on contact failure

To reveal the influence mechanism of the grinding surface quality of 20CrMnTi steel components on the tribological characteristics and contact fatigue performance, accelerated tests for sliding friction wear and fatigue damage were carried out. Tribological characteristics and contact fatigue performance get worse with increasing surface roughness while getting better with increasing surface microhardness. Residual compressive stress is conducive to inhibiting the initiation and propagation of cracks and promoting contact fatigue performance. Additionally, mechanical friction, abrasive wear, adhesive wear and fatigue damage coexist and form a competing failure mechanism under the synergistic effect of frictional wear and contact fatigue failure. The damage process mainly manifests as wear, stress concentration induced fatigue, microcracks, pitting, and spalling in the shallow layer. This study is more beneficial to promote the 20CrMnTi steel transmission parts manufacturing products for high precision, low damage, and long life.

Surface Roughness Model of Ground 4H-SiC Considering Ductile and Brittle Removal

Abstract Surface roughness is a critical indicator to evaluate the quality of 4H-SiC grinding surfaces. Determining surface roughness experimentally is a time-consuming and laborious process, and developing a reliable model for predicting surface roughness is a key challenge in 4H-SiC grinding. However, the existing models for surface roughness in wafer rotational grinding fail to yield reasonable results because they do not adequately consider the processing parameters and material characteristics. In this study, we proposed a new analytical model for predicting surface roughness in 4H-SiC wafer rotational grinding, which comprehensively incorporates the grinding conditions and material characteristics of brittle substrate. This model derives and calculates the material's elastic recovery coefficient based on contact mechanics and elastic contact theory. Subsequently, we modified the grain depth-of-cut model by incorporating elastic recovery coefficient. Additionally, we analyze the distribution of the failure mode (ductile or brittle) on the surface of a material when the depth at which the material is cut instead follows a random distribution known as the Rayleigh distribution. To validate the accuracy of the established model, a series of grinding experiments are conducted using various grain depth-of-cut to produce 4H-SiC wafers with different surface roughness values. These results are then compared with those predicted by both this model and the traditional model. The findings demonstrate that the calculated data obtained from the proposed model exhibit better agreement with the measured data. This research addresses the need for an improved surface roughness model in 4H-SiC wafer rotational grinding.

Surface Integrity of Binderless WC Using Dry Electrical Discharge Assisted Grinding

AbstractBinderless tungsten carbide (WC) is preferred for manufacturing tools, mould, and wear-resistant components. However, due to its high brittleness and hardness, the machined binderless WC surface is prone to generate microcracks and the machining efficiency is extremely low. Aiming at this difficulty, a clean and eco-friendly dry electrical discharge assisted grinding (DEDAG) method without any liquid medium was proposed for the processing of binderless WC. DEDAG principle was revealed and the DEDAG platform was first developed. A series of DEDAG, conventional dry grinding (CDG), and conventional wet grinding (CWG) experiments were conducted on binderless WC under different processing parameters. The current and voltage waveforms during the DEDAG process were observed, and the discharge properties were analyzed. The chip morphologies, surface hardness, residual stress, as well as surface and subsurface morphologies were analyzed. The results show that the surface hardness and roughness obtained by DEDAG are smaller than that by CDG or CWG. The measured residual tensile stress after CDG is larger against DEDAG. The ground surface by DEDAG has better crystal integrity than that by CDG. DEDAG can soften/melt workpiece material and diminish grinding chips, thereby promoting plastic removal and increasing processing efficiency. The influences of DEDAG parameters on the ground surface quality are also investigated, and the optimal DEDAG parameters are determined. With the increase of open-circuit voltage or grinding depth, the surface quality improves first and then worsens. The optimal open-circuit voltage is 40 V and the grinding depth ranges from 10 µm to 15 µm. This research provides a new idea for promoting the efficient and low-damage processing of binderless WC.

Study on nickel-based single crystal superalloy DD6 subsurface damage of belt grinding with a large cutting depth of one pass

Single crystal superalloy has been widely utilized as a crucial manufacturing material for aeroengine turbine blades due to its excellent properties. However, machining this alloy is easy to cause subsurface damage, resulting in the engineering failure of blades. To explore a large cutting depth and low damage processing method, this paper established a grinding depth analytical model for the abrasive belt. The model provides insights into the material removal behavior mechanism during belt grinding and predicts the impact of process parameters on the grinding depth. Subsequently, the grinding experiments of this alloy with different abrasive belts were conducted. The experimental results showed that grinding depth increased as normal force amplified and exhibited a nonlinear growth pattern with the reduction of feed velocity. This preliminary verified the prediction model of grinding depth. The material removal properties of the pyramid, diamond, and hollow-sphere belts were analyzed, and the ratio of material removal capacity for the three was found to be 12:8:5. Based on the analysis of the topography and roughness of the grinding surface, the study examined the influence mechanism of grinding force, feed velocity and abrasive grain morphology on grinding depth and surface quality. The subsurface damage behavior mechanism and recrystallization depth change law of belt grinding were revealed. The grinding depth of the pyramid and diamond belts could exceed 160 μm and the recrystallization depth was less than 5 μm. To achieve efficient and low-damage machining, it is recommended to reduce the feed velocity rather than increase the grinding normal force. It is important to note that the feed velocity should not exceed 10 mm/s. This study is to furnish a theoretical groundwork and offer engineering technical recommendations for achieving large grinding depth and low damage machining of single crystal superalloy.

Investigation of a green nanofluid added with graphene and Al2O3 nano-additives for grinding hard-to-cut materials

This study investigates Nanofluid Minimum Quantity Lubrication (NMQL) efficiency in grinding hard-to-cut materials by incorporating graphene and Al2O3 nano-additives into oleic acid-based nanofluids. Varied concentrations and ratios were examined, analyzing thermal conductivity, viscosity, and contact angle. NMQL assessment covered grinding force, specific grinding energy, temperature, surface quality, wear rate, and friction coefficient. Hybrid nanofluids displayed superior lubrication. At 1 wt% nano additives concentration, minimum specific grinding energies, friction coefficients, and friction test temperature increments were reduced by 73.92 %, 46.57 %, and 65.69 %, respectively in comparison with dry conditions. Optimal surface quality for ZrO2 and Ti-6Al-4V workpieces emerged at 2 wt% and 3 wt% nano additives concentrations, reducing surface roughness by 60.53 % and 48.66 %, respectively compared to dry cutting.

Grinding mechanism and surface quality evaluation strategy of single crystal 4H-SiC

This paper investigated the removal mechanism and surface quality of single crystal 4 H-SiC during the grinding process, as well as the impact of the measurement area on surface roughness (Sa) during surface morphology detection. This problem is relatively unexplored. Experimental findings suggest that when the measurement area is below 400 µm², there is a greater error in Sa. Conversely, when the measurement area exceeds 400 µm², the error in Sa values is relatively small and stable. The surface quality increases with the increase of wheel speed (vs) and decreases with the increase of workpiece feed rate (vw) and grinding depth (ap). This study finds that the material removal of monocrystalline single crystal 4 H-SiC during the grinding process occurs primarily through plastic deformation, accompanied by brittle fracture.

Research on the Grinding Performance of an Electroplated Coarse-Grained Diamond Grinding Wheel by Dressing

The coarse-grained electroplated diamond grinding wheels is increasingly favored in precision grinding of hard and brittle materials owing to its high material removal efficiency, high wear resistance and steady surface contour accuracy. However, how to determine whether the dressed grinding wheel surface topography can achieve the desired precision ground surface quality is still a huge challenge to this day. In this paper, a novel numerical simulation model, which was established basing on the statistical features of actual electroplated coarse-grained diamond grinding wheel and the kinetics of the grinding process, was proposed for theoretically and thoroughly studying the influence of the surface dressing depth of coarse-grained electroplated diamond grinding wheel on ground workpiece surface morphology. At first, the statistical features of actual electroplated coarse-grained diamond grinding wheel was acquired and a novel numerical grinding wheel surface model was established. Subsequently, a numerical ground workpiece surface simulation model was also developed. And then, the evolving mechanism of the grinding wheel surface topography with the dressed wheel surface abrasive grain protrusion height was theoretically studied by numerical simulation. Moreover, the influence of the wheel surface abrasive grain protrusion height on the ground surface roughness was thoroughly researched by means of theoretical model and experiments. The simulation and experiments results in this paper indicated that precision ground workpiece surface with nano-scale surface roughness can be acquired by grinding with a dressed grinding wheel with a certain abrasive grain protrusion height of 25% of the typical abrasive size. Comparing with the undressed grinding wheel (grinding wheel with original surface topography and not be dressed), the surface roughness Sa and Sq of the surface ground with a well-dressed wheel can achieving a significant decrease of 97.75–99.77% and 97.57–99.73%, respectively. Therefore, carefully dressing the electroplated coarse-grained diamond grinding wheel is of great significance for obtaining a precision ground workpiece surface quality.

Automatic detection and pixel-level quantification of surface microcracks in ceramics grinding: An exploration with Mask R-CNN and TransUNet

Microcrack damage on the grinding surfaces of engineering ceramics is inevitably incurred. To accurately evaluate the microcrack damage, an automatic detection and pixel-level quantification model based on the joint Mask R-CNN and TransUNet is developed. In addition, a joint training strategy is employed and the model is trained effectively on the image dataset of microcrack damage derived from the Si3N4 grinding, as captured by SEM. The Mask R-CNN demonstrates reliable automatic detection of microcracks, achieving an Average Precision of AP50 = 0.989 and AP75 = 0.864. Meanwhile, the TransUNet achieves fine segmentation of microcracks with complex characteristics, with an F1 score of 0.914 and an IoU value of 0.785. A skeleton-based quantification model of microcrack size is proposed, which delivers comprehensive and precise measurements of area, length, and notably, the width. The proposed quantification model provides a technical reference for the automatic evaluation of grinding surface quality.

Study on Grinding-Affected Layer of Outer-Ring Inner Raceway of Tapered Roller Bearing.

In the grinding of bearing raceways, the coupling effect between grinding force and heat in the contact area between the grinding wheel and the workpiece causes changes in the material structure and mechanical properties of the raceway surface layer, which can lead to the formation of a grinding-affected layer. The grinding-affected layer has a significant impact on the service performance and fatigue life of bearings. In order to improve the ground surface quality of the outer-ring inner raceway of tapered roller bearings and optimize the processing parameters, this paper presents a study on the grinding-affected layer. A finite element simulation model for grinding the outer-ring inner raceway of the tapered roller bearing was established. The grinding temperature field was simulated to predict the affected-layer thickness during raceway grinding. The correctness of the model was verified through grinding experiments using the current industrial process parameters of bearing raceway grinding. The research results indicate that the highest grinding temperature of the outer-ring inner raceway of the tapered roller bearing is located near the center of the grinding arc area on the thin end edge. As the workpiece speed and grinding depth decrease, the highest grinding temperature decreases, and the dark layer thickness of the grinding-affected layer decreases or even does not occur. The research results can provide theoretical guidance and experimental reference for grinding the raceway of tapered roller bearings.

Study on the dynamic influence of the distribution of cutting depth on the ground surface quality in a precision grinding process

Focusing on the excitation mechanisms of self-excited vibration and forced vibration, a time-delay differential model of the radial cutting depth of a single active abrasive grit is presented. Based on the principle of the layered superposition characteristics of each component of radial cutting depth, a full discrete simulation technology is used to analyze the dynamic mechanisms of different vibration excitations on the grinding characteristics. The reliability of the dynamic mechanisms is verified by the corresponding grinding experiments. The verification results demonstrate that static and dynamic components in the grinding dynamics, including radial cutting depth, grinding force, surface roughness and surface morphology of workpiece are greatly influenced by total material removal rate, followed by speed ratio and grinding directions. With the increase of cutting depth, the variation amplitude of grinding process influenced by forced-vibration mechanism are nearly twice larger than those influenced by self-excited vibration mechanism. When speed ratio reduces to a half, surface roughness of workpiece improves by nearly 33 %. The stability of machining process and finish surface of workpiece during up-grinding are better than those during down-grinding, where force reduction by up to 10 % and surface finish improvement by 37 %.

Wear-induced variation of surface roughness in grinding 2.5D Cf/SiC composites

As the ideal high-temperature component materials, Cf/SiC composites require high grinding surface quality for their final preparation. It is a challenging issue to achieve the desired surface quality of such hard brittle material with serious rapid tool wear. A surface roughness predictive model involving the grinding wheel cumulative wear was developed for grinding process of 2.5D needled Cf/SiC composites. Compared with the experimental data, the predicted ground surface roughness errors of 2.5D needled Cf/SiC composites are less than 12 %. It is found that due to the grinding wheel cumulative wear effects, the resin-bonded diamond wheel presented self-sharpening phenomenon as increasing specific material removal volume (SMRV). The grinding wheel cumulative wear effects are conducive to Cf/SiC ground surface improvement. When the SMRV reached 720 mm3/mm, the surface roughness decreased by 21.2 % with a 180# grinding wheel, and 8.6 % with a 280# grinding wheel. This work provides some insights for preparing the tool condition during grinding 2.5D needled Cf/SiC composites.

Fabrication of PCD face grinding wheel with positive rake angle by femtosecond laser and its performance evaluation in cemented carbide grinding

Super-hard abrasive grinding is considered to be the main approach to realize precision and ultra-precision machining of difficult-to-machine materials such as cemented carbide, engineering ceramics, titanium alloys and superalloy materials encountered. However, heavy grinding force, high grinding temperature and poor surface integrity are prone to be encountered in conventional negative rake angle grinding of difficult-to-machine materials. In response to these problems, a novel concept of positive rake angle grinding is first proposed and an abrasive grain regularly arranged binder-less polycrystalline diamond face grinding wheel with positive rake angle has been designed and fabricated by femtosecond laser ablation. To evaluate the grinding performance of the face grinding wheel with positive rake angle, grinding experiments of YG8 cemented carbide are conducted and compared with the traditional electroplated diamond grinding tool with equivalent abrasive grain dimension and distribution. The results show that compared with the conventional negative rake angle grinding, the normal and tangential forces in positive rake angle face grinding are reduced by 30.3 % ∼ 36.4 % and 21.1 % ∼ 29.3 %, respectively, and the ratio of normal to tangential force is reduced by 12.6 % ∼ 20.3 %. The surface roughness and average depth of subsurface metamorphic layer are also significantly smaller. The laser fabricated polycrystalline diamond face grinding wheel also has better wear resistance in the grinding of cemented carbide. Therefore, it can be concluded that better ground surface quality is obtained by the novel grinding wheel with positive rake angle. The innovative grinding method can fill the research gap on the grinding mechanism of positive rake angle grinding and further enrich the grinding theory of difficult-to-machine materials.

Reducing Wheel Loading in the Grinding of Titanium Alloys through Ultrasonic-Assisted Plasma Oxidation Modification

To reduce wheel loading caused by chip adhesion in the grinding of titanium alloys, a new method named ultrasonic-assisted plasma oxidation modification grinding is suggested. The processing principle was introduced in this research, and based on that, the experimental apparatus was established. Then, the surface and cross-sectional morphologies of a workpiece with an oxide layer were characterized, followed by the detection of its microhardness and surface composition. On this basis, in the absence and presence of the oxide layer, the dynamic changes in wheel loading on the grinding wheel surface and the evolution behavior of chip adhesion on the grains were both investigated after gradually increasing the grinding passes. Finally, the effects of wheel loading on the ground surface morphologies were analyzed. The results showed that the oxide layer with low microhardness was mainly composed of TiO2 and Al2O3. Moreover, with an increase in grinding passes, the overall occupied area of chip adhesion on the grinding wheel surface increased proportionally in the absence of the oxide layer, which finally caused severe wheel loading. Conversely, yet at almost the same rate, the overall occupied area of chip adhesion increased after remaining comparatively unchanged in a short range of grinding passes in the presence of the oxide layer, which effectively inhibited the wheel loading. Compared with the ground surface obtained without an oxide layer, the generation of plastic-stacking was significantly restrained with the assistance of the oxide layer, thereby improving the ground surface quality.