Influence Of Grinding Parameters Research Articles

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.

Understanding the machining mechanism in ultrasonic vibration-assisted nanogrinding of GaN

As a typical difficult-to-machine material, gallium nitride (GaN) crystals have the merits of excellent chemical stability and large bandwidth, which can be used in fields of space optical components, photoelectric devices, and electronic communication. The smooth surface of GaN is the basis of these applications. Grinding of GaN has thus drawn increasing attention. Furthermore, vibration-assisted nanogrinding has the potential to reduce grinding forces compared with conventional nanogrinding. In this study, ultrasonic-vibration-assisted nanogrinding of GaN with a single grit is conducted based on molecular dynamic (MD) simulations. The plastic deformation mechanism of GaN single crystals as well as the influence of grinding parameters, such as vibration period and amplitude, on the grinding outcomes are investigated. The MD simulations reveal that plastic deformation of GaN in the vibration-assisted nanogrinding process is dominated by amorphous transformation, dislocation, stacking faults, lattice distortion, and formation of nanocrystals. Furthermore, amorphous GaN atoms are mainly induced in front of the grit and at either side of the grinded groove. In the grinding process, the periodic fluctuation of grinding force components, which include the normal, tangential, and horizontal forces, are stable. A smaller grinding force is obtained when grinding with a small vibration period. Moreover, a small vibration period and large vibration amplitude lead to improved grinding efficiency, suppressing the grinding force and subsurface damage, and improving the grinding quality. The findings in this study facilitate an understanding of the plastic deformation mechanism of GaN single crystals and also provide guidance for parameter optimization during vibration-assisted nanogrinding.

Prediction model of grinding roughness for worm with complicated space tooth surface

Optimum grinding parameters are crucial for achieving high-quality grinding of helical tooth surfaces for worm drives. The complex coupling motion relationship and formation mechanism between the worm blank and the grinding head make it difficult to predict the effect of grinding parameters on tooth surface roughness. Therefore, we developed a prediction model for the worm tooth surface roughness under conjugate grinding and applied it to the Roller Enveloping Worm Reducer (REWR). The forming process of the theoretical worm tooth surface during the grinding process was modeled by using the conjugate meshing principle. Considering the plowing and cutting effects of grinding particles on the tooth surface at different design parameters, feed speeds, and rotational speeds of the grinding head, the roughness prediction equation was established based on the theory of the maximum depth of valley bottom. Through the coupling analysis of the theoretical tooth surface model and the roughness prediction model, the prediction of the worm tooth surface roughness is realized. Based on the validated model, the influences of grinding parameters on the worm tooth surface roughness of REWR were quantitatively discussed. This study is of great significance for optimizing process parameters in the grinding of complex spatial surface transmissions.

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.

Experimental investigation on the feasibility of high-efficiency and precision grinding of silicon carbide ceramics with monolayer brazed diamond wheel

To explore the feasibility of high efficiency and precision grinding of brittle ceramics, the experimental grinding tests were conducted on SiC ceramics with monolayer brazed diamond wheels. The monolayer diamond grinding wheel with 80/100 mesh size diamond grains was brazed using high-frequency induction techniques. The binarization method was proposed to quantitatively characterize the brittle removed areas from the whole ground surface and oblique polishing method was used to assess the subsurface damage depth of the ground SiC samples. The results show that the maximum undeformed chip thickness (agmax) plays a crucial role in the material removal mode. When agmax increases from 0.08 µm to 1 µm, the brittle-removal ratio increases rapidly from 8.20 % to 48.24 % and the subsurface damage depth increase from 3.48 µm to 9.14 µm by 162.6 %. The grinding wheel speed also has a significant influence on the brittle-removal ratio. With the gradual increase of grinding wheel speed (vs) from 20 m/s to 160 m/s, the brittle-removal ratio of the ground surface decreases from 34.24 % to 25.56 %, and the depth of subsurface damage decreases from 5.68 µm to 3.58 µm by 36.97 %. The effect of the grinding depth on the ground surface and subsurface is comparatively not remarkable. The influence of grinding parameters on the grinding process of SiC ceramics indicate that high speed, creep infeed and deep depth grinding method makes it possible to realize high efficiency and low damage machining for SiC ceramics with monolayer diamond wheel.

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.

Comprehensive investigations into the force and thermal characteristics of belt grinding Inconel 718 under constant normal forces

Belt grinding is an efficient and widely used method for machining precise high-strength components made from the superalloy Inconel 718. By integrating robots with a force sensor, normal forces can be kept to achieve high-accuracy grinding under varying processing conditions. However, the force and thermal characteristics of belt grinding Inconel 718 under constant normal forces, which significantly affect the quality of ground workpieces, are still unclear. In this study, four characteristics including grinding effects, dynamic grinding forces and force ratios, specific grinding energy as well as dynamic grinding temperature distributions, are comprehensively investigated. The grinding effects are determined by the single-grain scratch test, and the material springback mechanisms are revealed. The influences of grinding parameters on grinding forces, specific grinding energies and grinding temperatures are analyzed in detail. Additionally, a new finite element model is established to obtain the dynamic temperature distributions of grinding surfaces. This study aims to improve understanding of the process of constant-force belt grinding Inconel 718 and lays foundations for further research on grinding mechanisms and modeling.

Static numerical simulation of radial deformation of ultra-thin dicing blade

Grinding with dicing blade is an important method to cut or slot electronic and optical devices. The deformation of grinding tools will definitely affect the processing of workpiece. However, this effect has been disregarded during processing. In order to improve the machining accuracy in the precision grinding method, this deformation is worth considering. In this research, the grinding state of the ultra-thin dicing blade was simplified as a static problem. The force model of the ultra-thin dicing blade during grinding was established, which centrifugal force was adopted in the whole blade and triangular distribution grinding forces were adopted in the grinding area. The radial deformation of the ultra-thin dicing blade was determined by finite element simulation, and the influence of grinding parameters on its radial deformation was analyzed. The simulation results showed that the grinding area of the ultra-thin dicing blade occurred radial expansion deformation at high rotational speed (more than 8000 rpm), and the value could reach 1.75 μm (rotational speed at 23,000 rpm, feed speed at 600 mm/min, and grinding depth at 0.12 mm). The deformation increased in a form of power function with the increase of rotational speed, and decreased linearly with the increase of feed speed and grinding depth. This work can provide reference data for deformation compensation, which is helpful to improve the dimensional accuracy of grinding groove.

Investigation on Surface Integrity of Nodular Cast Iron QT700-2 in Shape Adaptive Grinding

Nodular cast iron QT700-2 is extensively used in automobile engine crankshaft parts due to its prime mechanical properties. The journal of a crankshaft is a curved surface, and traditional wheel grinding easily causes grinding burn and surface and subsurface damage. Shape adaptive grinding (SAG) is a flexible grinding technology, which has the advantages of low grinding force and temperature, and good grinding quality. It is suitable for machining curved surface parts with complex shapes. Therefore, the SAG surface integrity of nodular cast iron QT700-2 was experimentally investigated. The influence of grinding parameters on grinding force, material removal rate, grinding temperature, and surface integrity was studied, and the machining performance of SAG tools was evaluated. It was concluded that the grain size in SAG is the most important factor affecting the grinding force, material removal rate, and surface roughness; the influence of SAG grinding is very weak, mainly removing the workpiece material. Then, the influence law of SAG technology on the surface integrity of nodular cast iron QT700-2 was summarized, and the optimal grinding parameters were obtained, providing a reference for the curved surface grinding of nodular cast iron QT700-2 in the future.

Surface Morphology and Subsurface Microstructure Evolution When Form Grinding 20Cr2Ni4A Alloys.

20Cr2Ni4A alloy is widely used in the manufacturing of heavy-duty gears, although limited information about its machinability during the form-grinding process has been reported. In this work, form-grinding trials on transmission gears of 20Cr2Ni4A alloy under various parameters were conducted. Surface morphology of the gear tooth, surface roughness distribution and microstructure evolution of the machined surface layer were comprehensively studied, and the influence of grinding parameters on grinding performance was investigated. The formation mechanisms of surface/subsurface defects during the form-grinding process, including plastic flow, deep grooves, successive crushing zone, adhesive chips and cavities, were analyzed. Results showed that the change in contact conditions between the grinding wheel and tooth surface led to the decrease in the surface roughness from tooth tip to root. Mechanical force and grinding heat promoted the deformation and refinement of the microstructure within the machined surface layer. With the increase in cutting depth and feed speed, the deformation ratio of the microstructure increased, which was also consistent with the variation trend in the form-grinding temperature.

Three-dimensional topography modelling and grinding performance evaluating of micro-structured CVD diamond grinding wheel

Micro-structured chemical vapour deposition (CVD) diamond grinding tools are attracting increasing attention in precision grinding and micro-grinding because of their advantages in low grinding forces, high machining accuracy and good wear resistance. A well-developed wheel topography model for this kind of emerging grinding tool not only can facilitate the analysis and optimization the grinding process, but also is the essential basics for the intelligent machining. In this paper, a novel three-dimensional surface topography model of original CVD diamond grinding wheels was firstly established based on the multiple random data of the shape, size, posture and distribution of the CVD diamond grains. And the ground surface topography model was simulated depending on the established wheel model and grinding kinematics. Secondly, the models were verified by the results of grinding experiments in the means of topographical characteristics, surface roughness and PSD. Then, the influence of grinding parameters and wheel wear on the grinding performance of CVD diamond wheels was discussed. Finally, the micro-structured CVD grinding wheel models were presented by coupling different forms of micro-structures. And the effects of micro-structure parameters including widths, inclination angles, structuring ratios and types on the grinding performance of micro-structured CVD diamond wheels were investigated quantitatively. This study provides a quantitative and effective method for the design of CVD diamond grinding wheels and their surface structuring. Furthermore, the proposed micro-structured analysis method is also available for other structured grinding wheels.

Investigation on the influence of grinding parameters on surface integrity of substrate in metal additive forging

Additive forging technology is an innovative method for manufacturing heavy forgings by using multi-layer hot-compression bonding. To achieve better bonding performance, the surface of the metal substrate needs to be ground and cleaned before hot-compression bonding. However, the process is less automated in factory production which tremendously hinders the increase of productivity. This paper presents an automatic grinding scheme and the experimental device were designed to verify the feasibility of the scheme. The effects of contact pressure, spindle speed and feed speed on the grinding effect of 316H stainless steel were studied. The results show that the best grinding effect can be obtained when the contact pressure is 25 N, the spindle speed is 8000 rpm, and the feed rate is 30 mm/s, which can significantly improve the product quality and production efficiency.

Grinding Temperature and Surface Integrity of Quenched Automotive Transmission Gear during the Form Grinding Process.

Grinding burn is an undesired defect in gear machining, and a white layer is an indication of severe burn that is detrimental to gear surface performance. In this work, the influence of grinding parameters on the thickness of the white layer during form grinding of quenched transmission gear was investigated, and the microstructure evolution and mechanism of severe burn formation were analyzed. The grinding temperature increased with the grinding depth and grinding speed, with the highest level of ~290 °C. The thickness of the white layer exceeded 100 μm when the grinding depth was 0.03 mm, and the top layer was a plastic deformation layer followed by a fine-grained martensite layer. Coarse-grained acicular martensite was found at the interface between the white layer and softened dark layer. The mechanical effect and thermal softening mainly contributed to the formation of white layer stratification. The ground surface topography showed several scratches and typical grooves; when grinding depth increased to 0.03 mm, the grinding surface roughness Sa was relatively high and reached up to ~0.60 μm, mainly owing to severe plastic deformation under grinding wheel extrusion and the thermal effect.

Research on the mapping grinding of dimple surface with ordered pattern based on topological theory

Since the structured dimple surface is one of the important functional drag-reducing surfaces, the research on its efficient fabrication technology is of great significance for the practical application of this surface. Therefore, in order to grind structured dimple surface, a topological mapping grinding method for structured dimple surface was proposed based on grinding kinematics principle and point set topology. Firstly, the topological spaces of the workpiece and the grinding wheel were established, and the topological features of the structured dimple surface and the structured grinding wheel were extracted based on the analysis of the topography features of the structured surface with ordered pattern. Then, the topology mapping equation of the grinding process was constructed based on the analysis of the generating mechanism of the dimple surface about grinding geometry, and the structured grinding wheel was designed according to the topology mapping equation. Finally, according to the grinding geometry simulation, the influence of grinding parameters on the generating of dimple surface topography was studied, and the grinding experiment was carried out. The results show that the structured grinding wheel designed based on the topological features of the structured dimple surface can achieve the grinding of the structured dimple surface. The ground dimple surface is a topological dimple surface, and its feature parameters can be changed with the change of grinding parameters, but the topological feature attributes remain unchanged under the condition of satisfying the proper grinding speed ratio.

Research on Grinding Parameters of Parts with Same Clamping Mode and Different Sizes

Aiming to study the influence of ultra-precision grinding parameters on the accuracy between the same clamping method and different workpiece sizes. This paper mainly analyzes the difference between the measurement precision of different parts by the same measurement method and the measurement precision of the same parts by different measurement methods. Therefore, the influence of grinding parameters on grinding precision is reflected. For the same part, it is concluded that the coaxiality error coincidence degree at end A and end B reaches 90.32% and 95.27%, respectively by using precision three-coordinate measuring instrument and Mahr roundness instrument. The coincidence degree of end A and end B verticality error reached 97.54% and 91.08%, respectively. For parts with different sizes, the Mahr roundness meter is used for measurement. The analysis shows that the coaxiality coincidence at end A and end B is the highest, reaching 98.36% and 92%, respectively. And from the analysis, the errors are mainly reflected in the factors such as jig and fixture and grinding process.

Surface Roughness Characterization and Inversion of Ultrasonic Grinding Parameters Based on Support Vector Machine

Abstract With surface roughness restricted by grinding parameters, the characterization of roughness parameters and the inversion of grinding parameters are of great significance for improving surface performance and realizing active surface machining. This research proposes a combination of statistical theory and data-driven analysis to solve the above problems. Pearson correlation analysis and multivariate variance analysis indicate the correlation characterization parameter set (CPS) consists of Sa, Vmp, Vvv, and Sz and that there are differences in the influence of grinding parameters on the parameters in CPS. Adjustment of support vector machine (SVM) core parameters makes it possible to construct expansion parameter set (EPS) optimal inversion models. By designing pseudo-surface random roughness parameters and grinding experiments, the reliability of inversion models is verified. The results show: (1) The better generalization of inversion model indicates skewness Ssk and kurtosis Sku in EPS have important implications for the optimal inversion model and surface characterization and (2) The data-driven model based on support vector machine provides machining guidance for obtaining the expected ultrasonic grinding surface.

Research on roundness error consistency model for crank journal cylindrical grinding

Cylindrical grinding is an important way to form the external shape error of the crank journal, and the accuracy consistency directly affects the interchangeability of products. To study the accuracy consistency of crank journal, a dynamic model of the grinding wheel-crankshaft grinding system based on Timoshenko beam is established, and the grinding transition process simulation algorithm with iterative convergence of grinding force-transient grinding amount cycle adapted to the model is proposed, which realizes the simulation of the roundness of the crank journal coupled with the process parameters of the grinding system. Aiming at the grinding position of each crank journal, the grinding roundness of five crank journals is simulated, respectively. On this basis, the crank journal roundness consistency prediction model is established, and the effectiveness of the prediction model is verified by field experiments. Finally, the influence of grinding parameters on the consistency of the roundness of crank journal is studied. The research conclusion can provide a reference for the grinding accuracy consistency design of this type of crank journal.

Grinding-Hardening of Face Gears Under Minimum Quantity Lubrication with Disc Wheels

To shorten the process of face gears, the grinding-hardening effect experiment of face gears under minimum quantity lubrication(MQL) was carried out. Firstly, the grinding method of face gears was analyzed based on the envelope principle, and the control equation of grinding movement was constructed. Secondly, the distribution ratio equation of heat flux density was established, and the theoretical calculation formula of triangle heat source was derived. Thirdly, since a MATLAB calculation program was compiled, the temperature change law under MQL grinding was analyzed. In the end, the influence of grinding parameters on the grinding-hardening layer depth was analyzed. The results demonstrate that MQL grinding achieves the grinding-hardening effect.

Research on the metamorphic layer of silicon nitride ceramic under high temperature based on molecular dynamics

The high temperature of the grinding area at the engineering ceramic materials processing is one of the main factors affecting the quality of processing and the performance of parts. In order to reveal the law of temperature distribution of silicon, nitride ceramic grinding and its mechanism of action on surface quality. The process of machining silicon nitride ceramic material is simulated based on the established molecular dynamics model of the nanometric grinding of silicon nitride. The influence of grinding parameters on the nanometric grinding process is studied from the variation law of grinding temperature and the evolution of system energy, as well as the formation of grinding surface and metamorphic layer during machining. And the results of the experiment were compared with the theoretical research. With the increasing of grinding depth and speed of diamond grains, the energy released during the deformation and amorphous phase change of the atomic lattice get increased, and the grinding temperature get increased. The high grinding temperature will cause amorphous phase change in silicon nitride ceramics, and the amorphous atoms are recombined with the atomic bonds of the processed surface to form a metamorphic layer of the processed surface. The effect of grinding parameters on temperature changes from large to small is grinding wheel line speed, workpiece feeding speed, and grinding depth. There is an important effect on improving the surface machining quality and the service life of parts of engineering ceramics such as silicon nitride from the results of this paper, and it also plays an important role in reducing the effect of grinding temperature on the surface quality.

Bionic Structure on Complex Surface with Belt Grinding for Electron Beam Welding Seam of Titanium Alloy

Electron beam welding (EBW) is widely used to weld titanium alloy parts such as aero-engine casing and blades. The surface quality after EBW has a significant influence on the aero-engine performance of those parts. We propose a surface treatment method with grinding on a titanium alloy electron beam weld. We analyze the influence of grinding parameters on the characteristics of the grinding surface. The experiment shows the applicability of ground surface by belt grinding on EBW and its impact on aero-engine performance. After belt grinding, both the welded surface and the surface connected with the substrate are smooth. The extra height of the seam was less than 0.2 mm, and the surface roughness (Ra) of the weld after grinding can be less than 0.98 μm. The microstructure of the weld after grinding was analyzed. Two types of bionic shapes were obtained, a sawtooth shape with a width of 40 μm and a height of 10 μm and a wavy shape with a width of 20 μm and a height of 3 μm. From the analysis above, the bionic surface can be obtained by grinding on the weld with an abrasive belt.