Grinding Characteristics Research Articles

Experimental research on grinding characteristics of AlCoCrFeNi2.1 dual-phase high entropy alloy

Experimental research on grinding characteristics of AlCoCrFeNi2.1 dual-phase high entropy alloy

The Study of Post-Harvest Processing and Handling of Residues From Plants Grown Primarily For Agronomics: Soybean Stalk, Corn Stover, Tomato Vine, Cucumber, Eggplant, and Summer Squash

Information on post-harvest handling of the crop is critical to the development of new or improved plant species and traits. This paper presents a comprehensive study of the grinding characteristics and handling properties of a number of crop residues under agronomic studies. We used a laboratory-scale knife mill connected to an in-line power meter to investigate the specific energy of size reduction for each crop. The summer squash sample yielded the smallest mean particle size upon grinding (P= 0.05). The results indicate a significant correlation between the Carbon to Oxygen (C/O) ratio and the Gross Calorific Value (GCV), ash, lignin content, and net specific grinding energy consumption (NSGEC) of the samples. Among agricultural residues, the soybean stalk sample, with the highest C/O ratio (0.96), exhibited the highest GCV (17.5 MJ/kg, db) and NSGEC (31.7 kWh/t), while the summer squash sample, with the lowest C/O ratio (0.46), showed the lowest GCV (13.6 MJ/kg, db) and NSGEC (5.1 kWh/t). The flowability of the ground biomass samples varied, with cucumber showing the best free flow properties. The results also showed that there is a significant positive correlation between the lignin content and NSGEC of all samples (p= 0.05).

The impact of mono-ethylene glycol on ordinary Portland cement: Exploring grindability, workability, hydration, and mechanical properties

Glycol-based components are commonly used as grinding agents in ordinary Portland cement (OPC). However, their effects on the grindability and hydration mechanism have not been fully understood. In this study, the effects of mono-ethylene glycol (MEG) of various concentrations (0, 0.025, and 0.05 %) on OPC grinding characteristics as well as hydration reaction were examined. The use of MEG improved the grinding performance of OPC powder, and this effect became more noticeable with increasing quantities of MEG. Moreover, the addition of MEG substantial influenced the hydration properties of the OPC. Although there was no substantial difference in the reactivity of the aluminate phases, the reactivity of the silicate phases improved at all stages. This effect intensified with increasing concentrations of MEG. Additionally, the amount of calcium carbonate increased with the addition of MEG, indicating that MEG somehow promotes carbonation as well. With all these effects, it was concluded that the MEG proportionally enhanced the mechanical performance.

Grinding defect characteristics and removal mechanism of unidirectional Cf/SiC composites

Grinding defect characteristics and removal mechanism of unidirectional Cf/SiC composites

Investigating the Influence of Medium Size and Ratio on Grinding Characteristics

This study explores the effect of steel ball size and proportion on mineral grinding characteristics using Discrete Element Method (DEM) simulations. Based on batch grinding kinetics, this paper analyzes the contact behavior during grinding, discussing particle breakage conditions and critical breakage energy. The results indicate that while increasing the size of the steel balls leads to higher collision energy, the collision probability decreases significantly; the opposite is true for smaller steel balls. Simulation results with different ball size combinations show that increasing the proportion of smaller balls does not significantly change the collision energy but greatly increases the collision probability, providing a basis for optimizing ball size distribution to improve grinding performance. Furthermore, appropriately increasing the proportion of smaller balls can reduce fluctuations in grinding energy consumption, thereby enhancing collision energy and collision probability while reducing energy costs. Liner wear results demonstrate that larger ball sizes increase liner wear, but different ball size combinations can effectively distribute the forces on the liner, reducing wear.

Comparison between high-pressure steam and vinegar stir-frying on grinding characteristics and nutrient components of turtle shells: Difference between carapace and plastron

The nutritional differences between the carapace and plastron of turtle shells, and their grinding challenges, are not well understood. This study aimed to evaluate the nutritional differences between a turtle shell’s carapace and plastron, and the effects of high-pressure steam (HP) and vinegar stir-frying (VS) pretreatments. The carapace showed higher crude protein and fat but lower ash than the plastron. Both pretreatments reduced grinding energy and increased ash content while decreasing protein and amino acids levels. HP resulted in more water-soluble extract (15.13 %), protein (17.26 %), and peptide (20.77 %), whereas total free amino acids (FAAs: 545.62 mg/100 g) were increased by VS. Nutritional value was comparable between carapace and plastron. Additionally, in contrast to the conventional VS pretreatment approach, the HP method not only enhances the grinding process of turtle shells but also promotes the release of their water-soluble constituents. This advancement sets a solid foundation for future comprehensive studies aimed at exploring the nutritional potential of turtle shells.

Investigating the grinding characteristics of vanadium-titanium iron ore tailings for sustainable utilization in cementitious material preparation

The study of the cementitious material activity of industrial solid wastes is a key issue in the comprehensive utilization of its green building materials. In this study, mechanical activation was used to prepare cementitious materials from vanadium-titanium iron ore tailings (VTIOT) as the main raw materials, and the effects of grinding time, the key parameter, on the grinding characteristics of VTIOT, the mechanical properties of the VTIOT cementitious material, and the hydration mechanism were investigated by means of surface area analysis, particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), alkali leaching, mechanical testing, hydration heat analysis, and thermogravimetric analysis (TGA). The results show that: the grinding time and specific surface area of VTIOT exhibit a linear correlation. Prolonging the grinding time, the fractal dimension of the particles gradually increases. The activity of Si4+ and Al3+ elements increases rapidly, reaching a Si4+ and Al3+ content of 96 mg·L−1 at 90 min of grinding. With a VTIOT mixing amount of 30 %, a mortar paste ratio of 1:3, and a water cement ratio of 0.5, the 50 min ground VTIOT mortar demonstrates 7 d and 28 d compressive strengths of 29 MPa and 38.7 MPa, corresponding to the highest values of the activity index, measured at 71.4 % and 75.2 %, respectively. Under standard curing conditions, the hydration products of cementitious materials at 7 d are ettringite (AFt), calcium silicate hydrate (C-S-H), alumina, ferric oxide, monsulfate (AFm), calcium hydroxide (Ca(OH)2), and calcium silica (CS). In the hydration process of 7 d, the exothermic peak and exothermic amount of the 50 min VTIOT cementitious materials are greater than those observed for other grinding times, but lower than those of pure reference cement.

Fracture mechanism of ultrasound-assisted scratching 2D-SiCf/SiC composite fibers with different fiber orientations

The aim of this paper is to investigate the grinding characteristics and mechanism of 2D- SiC/SiC composites with 0°/90° orthogonal anisotropic structured surfaces under different scratching fiber angles (angle between scratch direction and fiber orientation, SFA). A series of surface single abrasive scratching tests were conducted. The effects of the scratch fiber angle on the grinding force, surface morphology and roughness were investigated. The results show that the scratch force and surface roughness at different scratch fiber angles are in the order of 0° > 30°> 45°; SFA also has an important effect on the surface microstructure. The grinding mechanism of 2D-SiCf/SiC composites was analyzed by single-particle scratching test. The results of the scratch force and surface morphology provide strong evidence of the differences produced during the grinding process. The advantages of ultrasonic vibration over conventional machining were further identified by comparing specific scratch energies. This study elucidates the damage behavior of 2D-Sicf/sic composites in correlation with the influence of angle, and these results provide a new guideline for ultrasonic vibratory grinding of woven fiber-reinforced ceramic matrix composites for machining quality.

Reducing Cf/SiC composite damages through collaborative control of laser ablating depth and grinding modes

Cf/SiC composites are regarded as difficult-to-machine aerospace materials. A low-damage surface machining of Cf/SiC composite by laser-ablating assisted grinding (LAAG) was conducted, and investigated the effects of laser-ablating depth and grinding modes on surface/subsurface damages. The results showed that ablated material depth reached 420 μm after 1200 times scanning, while the effective ablating rate was inhibited by the depth. Compared with down grinding, the grinding forces and temperatures were substantially higher in up grinding, with a maximum increase of 123.5 % and 140 % in normal and tangential grinding forces, respectively; however, micro brittle fracture and ductile removal were remarkably enhanced in normal and transverse fibers, and surface macroscopic damage has been suppressed; subsurface damage remained insignificant, mainly exhibited in internal micro cracks and minor interfacial debonding. It was attributed to cutting characteristics of up grinding. Furthermore, as grinding depth increased, the material removal behavior underwent a brittle-ductile transition and the surface roughness grew accordingly. Moreover, a laser scanning angle of 0° and up grinding facilitated the occurrence of longitudinal fiber debonding, producing larger sized fiber bundle chips. Combining up grinding with 90° scanning angle at low grinding depth was an effective method to improve the surface quality of Cf/SiC composite.

Prediction of contact characteristics of abrasive belt compliant grinding for aircraft blades

Prediction of contact characteristics of abrasive belt compliant grinding for aircraft blades

An Investigation Into the Grinding Characteristics and Wear Evolution of Micro-Elastic Composite Grinding Pads

Abstract This paper introduces a novel micro-elastic composite grinding pad for material removal. The study also developed a new grinding wear formula grounded in microcontact mechanics, which is crucial in examining the evolution of interface characteristics under optimal parameter combinations. The results showed that the material removal rate (MRR), reduction of roughness height (σ), and peak curvature radius (ρ) increase were the highest in the initial stage, followed by a slight increase in the real-contact area in the second stage. This research suggests that abrasive particles primarily detach from the elastic pad in the second stage. The plasticity index (ψ) decreases during grinding, which suggests a transition from an elastic–plastic mixed contact interface to a predominantly elastic contact interface. This shift in the interface mechanics explains the gradual reduction in wear at the grinding interface. Both the plasticity index and the MRR are consistent throughout the grinding process. However, the plasticity index is a more effective index of interface wear than the conventional H/E ratio because it considers the surface roughness’s shape and size, which is essential in mild grinding operations. The findings of this study can be used to improve the design and performance of micro-elastic composite grinding pads and to optimize the grinding process for improved efficiency and sustainability.

Detection methods and bearing failure characteristics analysis related to grinding burns

Grinding burn is one of the bearing failure causes for components. In order to quickly confirm that grinding burn is the cause of bearing failure, detection methods for the grinding burns and characteristics of bearing failure caused by grinding burns have been studied in this paper. The results show that cold acid pickling examination, microhardness test and Barkhausen noise analysis can be used in the detection of heavy grinding burns but have several disadvantages to hinder their application on the detection of slight grinding burns. A grinding burn detection procedure is recommended for the analysis of bearing failure induced by grinding burn. It has been found that the modes of bearing failure induced by grinding burns were contact fatigue spalling developed from the contact fatigue crack, the propagation mechanism of the contact fatigue crack was obtained. And the unique phenomenon of fracture or fragmentation with cracks distributed in the origin or surrounding the spalling pit of the grinding burn layer was also obtained. Based on the above results the future work on detection methods and influence on bearing failure mechanism and life of grinding burn are proposed.

Surface crack analysis of 8Cr4Mo4V steel based on Crystal/Phase microstructure model by grinding

Metal polycrystalline materials tend to be homogeneous and isotropic at the macroscopic level, which leads it difficult to visually characterize the sprouting and expansion of cracks by traditional grinding simulation. In this study, the Johnson–Cook constitutive model was used for the finite element method (FEM) based on grinding characteristics with a high strain rate and large plastic deformation. The models are focused on the actual microstructure distribution, one of them contains grains and grain boundaries, and another contains phase organization (martensite and acicular martensite) and carbides. The study pinpoints the changes in microstructure under different grinding parameters during the grinding process and the influences on the formation of microscopic cracks. Ultimately, it was found that the shedding of large primary carbide is a critical factor for inducing surface cracks. The uncoordinated deformation between brittle carbides with the other phases is the main cause of carbide shedding. Therefore, this article visualized shows the influence of grinding parameters on surface cracks from the perspective of microstructure modeling, which is of great significance in guiding practical processing.

Understanding machinability improvements and removal mechanism of ceramic matrix composites during laser-ablating assisted grinding

Ceramic matrix composites are advanced high-temperature materials for aerospace equipment, but they are also known as hard-to-machine materials. This study introduced laser-ablating assisted grinding (LAAG), and analyzed the complex physicochemical transformations of Cf/SiC composites during picosecond-laser ablating, then systematically explored the grinding characteristics, damage behavior, removal mechanism, and abrasive wear. It was revealed that Cf/SiC composites occurred sublimation and oxidation reactions during laser ablating, resulting in SiO2 ablation products with a loose microstructure. Grinding force, temperature and diamond wear remarkably decreased through LAAG. Besides, surface roughness was observably reduced, and the surface morphology of Cf/SiC composites was primarily shown as micro fracture and ductile removal. Furthermore, subsurface damages, including fiber pulling-out and interface debonding, were almost invisible after LAAG. More importantly, the graphite crystallites of carbon fibers near the ground surface became disordered, and an amorphous structure layer was first found on the micro-fractured carbon fibers. The grinding chips generated in LAAG were lamellar-fractured ablated materials rather than uncharacteristically-fractured fiber bundle, indicating the anisotropy removal behavior of Cf/SiC composites was decreased. The machinability improvements were especially significant when the laser scanning interval was small and the scanning direction was perpendicular to the grinding feed direction.

Phenomenon of Lagging in the Values of Grinding Wheel Performance Characteristics Due to the Radial Transformation of the Cutting Surface of a Wheel under Abrasive Diamond Treatment

Phenomenon of Lagging in the Values of Grinding Wheel Performance Characteristics Due to the Radial Transformation of the Cutting Surface of a Wheel under Abrasive Diamond Treatment

Effect on Fine Particles Output Characteristics of Ceramic Ball Grinding

Steel balls as traditional grinding media are prone to excessive fines generation and high energy consumption. Therefore, in light of this problem, the authors investigated another media—ceramic balls based on the output characteristics of fine particles. This study discusses the effect of ceramic balls on the change of the particle size distribution, zero-order output characteristics, micro-strain, and collision energy in ground products. The results showed that for −10 μm particle size, ceramic balls have a smaller production rate than steel balls. In addition, when the filling rate of ceramic balls is 40%, the yield of −10 μm is reduced compared to steel balls. Therefore, ceramic balls greatly reduced the overgeneration of fines. Additionally, the micro-strain rate of ceramic ball grinding with time is 67% lower than that of steel ball grinding. Furthermore, ceramic balls cannot only mitigate excessive fines generation but also effectively reduce energy consumption.

A grinding force model considering the arc-track feeding unit device in ELID grinding of the non-standard ultra-precision bearings

Bearings play an important role in the national defense industry. The demands for the ultra-precision non-standard bearings are increasing year by year. Correspondingly, the requirements for the surface roughness of bearing raceways are getting higher and higher. The surface roughness Ra value of the bearing groove raceway has been significantly improved by the ELID (Electrolytic In-Process Dressing) grinding assisted by the arc-track feeding unit. In this research, a grinding force model for the ELID groove grinding assisted by the arc-track feeding unit is established. The modelling of the swing speeds, swing angles and duty ratios of the arc-track feeding unit are carried out as the basis for the predicting of the tangential and the normal forces. For the first time, the equivalent elastic modules are used to characterize the variation of the ELID oxide layer in the new model. Validated by the linear-groove ELID grinding with varying swing speeds, swing angles and duty ratios of the arc-track feeding unit, the predicting results of the force capture well the fluctuation of different force components due to the changing of the variables. The new grinding force model involving the arc-track feeding device is able to give accurate predictions to the tangential and normal forces. The maximum error between the predicting tangential forces and the experimental tangential force is 5 %; the maximum error between the predicting normal forces and the experimental normal forces is 6.2 %. It provides an insight into the material removal mechanism and the grinding force characteristics in the ELID grinding assisted by the arc-track feeding unit for further improving the forming accuracy of this new method.

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 %.

Comprehensive investigation into grinding characteristics and damage behavior of Cf/SiC composite modified by picosecond-laser ablating

Cf/SiC composite is known as difficult-to-machine materials. This study introduced laser-ablating assisted grinding (LAAG) method, and explored the relationship between processing parameters and surface/subsurface damage behavior of Cf/SiC composite. It was revealed that SiO2 ablation products with a loose structure were formed during picosecond-laser ablating, and the ablated layers showed excellent machinability during grinding. Cf/SiC composite underwent brittle removal during conventional grinding (CG); however, significant ductile fracture and smeared removal appearance were clearly observed on the ground surfaces during LAAG. As the grinding speed increased, the grinding forces during LAAG were further decreased, and the brittle-ductile transformation of the normal fiber became more significant. The increase of feed speed would increase the grinding forces and enhance the brittle removal behavior of Cf/SiC composite. The laser power affected the machined quality through the ablation depth and the ablative transformation, and a smaller laser scanning distance would result in a flatter ground surface. Furthermore, subsurface damage of Cf/SiC composite after LAAG was slight, which primarily displayed as interface debonding and SiC matrix cracking. The grinding chips generated during LAAG were primarily composed of cut fiber-bundle and curled SiC matrix, rather than macro-fractured fiber and matrix with unordered size and shape.

Dielectric Roasting Induced Physical, Mechanical, and Grinding Characteristics of Black Pepper (Piper nigrum)

The present study was focused on microwave (dielectric) roasting (300-600 W, 5-15 min) on the physical, textural, color, and grinding of black pepper. The microwave roasting is a volumetric heating that causes rapid removal of moisture, and internal pressure generated inside the seed tends to change the physiology and physical attributes. An increase in roasting power and time increased the geometric mean diameter (5.216 to 6.283 mm), sphericity (0.883 to 0.927), aspect ratio (0.853 to 0.914), and surface area (85.560 to 124.262 mm2) of black pepper. Whereas the significant ( p < 0.05 ) reduction was observed in 100 grain weight (7.55 to 5.63 g), bulk density (500.97 to 251.38 kg/m3), fracturability (72.99 to 1.78 N), and hardness (63.65 to 1.61 N). Roasting led to browning, and a significant reduction was observed in the color parameters, L ∗ (22.82 to 17.76), a ∗ (2.47 to 0.56), and b ∗ (2.41 to -0.75) with a significant ( p < 0.05 ) increase in total color difference (0.96 to 5.30). Roasting also increased the particle size distribution in grounded power, and the mean particle size increased from 121.72 to 146.14 μm.