High-efficiency Grinding Research Articles

Dual admixtures for cement-based composites comprising steel slag powder and residual lignin-based liquor

Steel slag is a by-product of the steel industry that can be used as an aggregate and/or mineral admixture, conferring physical and mechanical benefits to cement-based composites. In parallel, sugarcane bagasse is a by-product of the sugar/alcohol industry used in biorefineries to produce bioethanol. The delignification processes, employed as a pretreatment in biorefineries, generate residual liquors that contain lignin. Lignin is a natural polymer with plasticizing properties when incorporated into cement mixtures. Given this scenario, this work sought to produce and evaluate dual admixtures containing a residual lignin-based liquor and a steel slag powder. The proposed dual admixtures were prepared from two strategies and incorporated in cement pastes and mortars at different dosages. Mixtures containing a commercial silica suspension and a reference mixture (without admixtures) were also evaluated. The flow test showed that the dual admixtures promoted higher spreading than the silica suspension in all the proposed dosages. Also, the mortars containing the dual admixtures had significantly higher compressive strengths and more refined pore structures than the reference mortar. The residual lignin-based liquor enhanced the workability of the composites and favored the dispersion of the steel slag powder into the matrix. The liquor's plasticizing and set-retarding capacities were attributed to its anionic functional groups and sugar content, respectively. Additionally, the high-efficiency grinding of the steel slag powder contributed to improving its specific surface area and fineness parameters, justifying its performance as a filler and a supplementary cementitious material. This study presents a new route for developing more eco-efficient cement-based composites. It also complies with the principles of circular economy by offering a feasible strategy for valorizing large-scale industrial wastes in civil construction.

Thermal behaviors in the metal high-efficiency grinding process under simulated vacuum conditions: state of the art and future perspectives

Thermal behaviors in the metal high-efficiency grinding process under simulated vacuum conditions: state of the art and future perspectives

Micro- and nano-hybrid cellulose fibers prepared by straightforward and high-efficiency hot water soaking-assisted colloid grinding for high-performance cellulose paper

Micro- and nano-hybrid cellulose fiber (MNCF) stands out as a versatile cellulosic nanomaterial with promising applications in various fields owing to its excellent intrinsic nature and outstanding characteristics. However, the inefficiency in preparing MNCF, attributed to a complex multi-step processing, hinders its widespread adoption. In this study, a straightforward and highly efficient method for MNCF preparation was developed via a hot water soaking-assisted colloid grinding strategy. Active water molecules in hot water facilitating stronger transverse shrinkage and longitudinal expansion in fiber crystallized region, and thus improving the fibrillation degree of cellulose fibers. As a result, MNCFs with a mean diameter of 37.5 ± 22.2 nm and high concentration (2 wt%) were successfully achieved though pure mechanical method. The micro and nano-hybrid structure leads to the corresponding resulting cellulose paper with micro- and nano-hybrid structure possesses a compact stacking and fewer defects, leading to extraordinary mechanical properties including tensile strength of 204.5 MPa, Young's modulus of 6.3 GPa and elongation of 10.1 %. This work achieves significant progress towards straightforward and highly efficient production of MNCFs, offering an appreciable prospect for the development of multifunctional MNCF-based materials.

Experimental Study on ELID Grinding of Silicon Nitride Ceramics for G5 Class Bearing Balls

This study has focused on analyzing the impact of material characteristics and grinding conditions on the surface roughness in ELID grinding of ceramic materials intended for bearing balls. The main research objective was to examine the feasibility of achieving the required surface roughness for G5 class bearing balls through a high-efficiency and high-precision ELID grinding process. Three types of silicon nitride specimens and two types of grinding wheels with cBN and diamond abrasives were prepared for the experiments. An HP (high-pressure) specimen was fabricated through high-temperature and high-pressure sintering at 1700 °C for 2 h, containing a composition of Y2O3 and MgO in Si3N4, while GPS 1hr and GPS 6hr specimens were prepared using gas-pressure sintering for 1 h and 6 h, respectively. From the experimental results, it has been confirmed through surface morphology and surface roughness analysis that material characteristics and grinding parameters affect the surface roughness of silicon nitride ceramics during the grinding process. The surface ground with a #2000 diamond wheel is at a level that can satisfy the required surface roughness, 0.014 um or less in G5 class bearing balls. Based on the analysis of surface morphology and roughness in grinding processes, the #325 cBN wheel exhibited excellent performance in rough grinding, while the #2000 diamond wheel demonstrated highly effective surface finishing performance, indicating that the combination of these two abrasives can be effectively utilized for high-efficiency and high-precision nanosurface machining of silicon nitride ceramics.

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.

Parameters Optimization of Laser-Grinding Chain for Processing Groove of 2.5-Dimensional C/SiC Composites.

Aiming at problems such as poor precision of laser processing C/SiC composites, low efficiency of grinding C/SiC composites, and serious wear of grinding wheel, a method of laser-grinding chain processing C/SiC composite groove was proposed in this paper. The method combined the high efficiency characteristic of laser ablating and the high precision characteristic of grinding. The relationship between laser processing parameters and the characteristics of ablative grooves was investigated, and the appropriate laser processing parameters were optimized, and then, to further improve the processing quality of the grooves, the grinding parameters optimization experiments of the grooves of C/SiC composites were carried out. The results showed that the C/SiC composites could be quickly removed by laser processing, and the grooves with relatively good size and shape accuracy could be obtained by laser parameters optimization experiments, but the side wall of the groove still had a certain inclination and the surface quality of the groove was yet poor; meanwhile, the size accuracy, shape accuracy, and surface quality of the grooves were greatly improved by further grinding. In addition, then, through the laser and grinding optimization experiments, the optimized parameters were obtained, where the laser power was 80 W, the scanning speed was 300 mm/s, the scanning frequency was 50 kHz, the scanning spacing was 25 μm, the depth of cut was 30 μm, the liner speed of wheel was 62.832 m/min, and the feed speed was 10 mm/min. With these parameters, the time used to process the groove with the laser-grinding chain was about 23/40 of the grinding process, and the quality of grooves could be guaranteed. Therefore, combined with the optimized process parameters, the laser-grinding chain processing scheme could be used to achieve high efficiency and precision grinding of C/SiC composite grooves.

Novel designed mechanical-mechanochemical synergistic micro-grinding technology and compounded abrasive micro-grinding tools

The mechanical and mechanochemical synergistic micro-grinding technology was proposed for grinding hard and brittle materials, especially for fused silica micro parts in this work. Compounded abrasive micro-grinding tools with diamond abrasives on the outer layer and cerium oxide abrasives on the inner layer were designed and fabricated. Efficient grinding was initially achieved by mechanical processing of super hard abrasives, and then ultra-precision processing was obtained by mechanochemical process to remove surface or subsurface damage. This study firstly analyzed the contact model of single diamond abrasive particle and theoretically evaluated ground surface roughness. The mechanism of abrasive layer wear was investigated for accurate error compensation. The formulation of cerium oxide abrasive layer and its processing efficiency were further analyzed. The material removal mechanisms of fused silica during mechanochemical grinding were also studied. Results showed that the material removal rate was 1.924 μm/min and the surface roughness Ra was 0.248 μm after mechanical processing. Subsequently, the surface roughness Ra was improved to 38 nm after mechanochemical processing. The study indicates that this technique is a promising approach for high-efficiency and high-quality grinding of fused silica.

Start-up behavior of oscillating heat pipe in grinding wheel under axial-rotation conditions

• Start-up timing behavior of AR-OHP is characterized and studied. • AR-OHP filled with acetone has a fast start-up speed followed by methanol & water. • Start-up mode turns from over-damped to under-damped/ transient mode with increase of cooling. • Centrifugal acceleration improves AR-OHP flow motion and increases start-up time. • Start-up mode becomes over-damped mode @ a =738m/s 2 and benefits temperature control. High efficiency grinding of difficult-to-machine materials can generate a good amount of heat in a short time. If the heat is not timely transferred, the accumulation of heat will cause a high grinding temperature and can be harmful to the machining quality. The oscillating heat pipes (OHP) are designed in the grinding wheel to directly transfer out grinding heat when axial rotating with the grinding wheel. To avoid sudden burnout of the workpiece in high efficiency grinding, the OHPs in the grinding wheel are supposed to dissipate a high heat flux in a very short time, therefore, such OHPs should start-up very quickly. The start-up speed of the OHP plays an important role in the grinding efficiency and quality, while the study on the start-up behavior of the OHP under axial-rotation is insufficient. Given that, the start-up process of the OHP under axial-rotation is here described and characterized, and the insurgence of the start-up is evaluated by the settling time and the rising time. Besides, the influences of the working fluids, cooling conditions, and centrifugal accelerations are studied. As expected for other kinds of OHP, also for the present OHP, the OHP filled with acetone has the shortest start-up time (20s), followed by the OHP filled with methanol (45s), while the water as the working fluid has the longest start-up time (46.5s). Along with the increase of cold air pressure, the settling and the rising time decreases significantly, e.g., for acetone, the settling time decreases by 59% - 87%. The centrifugal acceleration promotes the OHP flow motion and heat transfer, in turn, increases the start-up time. Besides, the start-up behavior turns from under-damped mode to over-damped mode, which has no temperature overshoot and is beneficial to the temperature control for thermal management in axial-rotation scenarios.

Wheel wear behavior and its influence on grinding performance in electrical discharge diamond grinding of reaction-bonded silicon carbide

Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.

Effect of Slurry Concentration on the Ceramic Ball Grinding Characteristics of Magnetite

Ceramic grinding, which in this paper is defined as a method of using ceramic materials as grinding media, is favored by many processing plants as an emerging high-efficiency and energy-saving grinding method. This paper investigates the effect of slurry mass concentration on the grinding characteristics of magnetite by taking the feed of the secondary ball mill for processing magnetite as the research object. The study results show that the slurry mass concentration significantly affects the ceramic ball grinding characteristics of magnetite, especially for coarse particles. When the grinding concentration is higher than 50%, the breakage rate of magnetite plummets to 1/3 of the value at low mass concentrations. The standard deviation of the breakage rate relative to the concentration gradually decreases as the feed size falls, indicating that the coarser the feed size, the more sensitive the ceramic ball grinding is to the concentration, and thus industrial secondary ceramic ball mills need to avoid grinding under high-quality concentrations. The change in the consistency parameter of distribution function and zero-order output characteristics signals a radical variation in the grinding characteristics of magnetite using the ceramic ball grinding method compared to conventional grinding. Because the ceramic ball grinding method can greatly reduce energy consumption while lowering the chance of overgrinding, this grinding method deserves more attention as the world works to reach carbon neutrality and emissions peak.

Wear characteristics of brazing diamond abrasive wheel on high efficiency grinding ferrous metals

A kind of diamond abrasive grinding wheel was brazed in high vacuum furnace using Ni–Cr–P–Si active powder filler alloys. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectra and X-ray diffraction (XRD) technique analysis were applied to investigate the wear characteristics of brazing abrasive grinding wheel during the process of dry cutting ferrous metal and the interface characteristics of brazing diamond grains to steel substrate. The reaction products such as Cr7C3 and Cr3C2 carbides with columnar shape were formed toward around the diamond brazed interface. The results showed that diamond brazing abrasive wheel had an advantage in terms of more high efficiency and safety than resin grinding wheel during the process on cutting ferrous metals. The main tool wear model was abrasive grains broken, fracture and corrosion which were near the brazed interface. It revealed that the cutting chips were adhered to the surface of broken grains and covered the abrasive grits during the cutting process where arising high temperature on the grinding arc zone. Results proved that the graphitization phenomenon of diamond grits was slightly occurred and the diamond bonding strength was strong enough to meet the requirements of high efficiency and heavy load machining on dry cutting cast iron. The experiment also demonstrated that a kind of safety, high strength and super sharp diamond abrasive wheel could raise machining efficiency on cutting ferrous metal materials.

Fabrication of micro-nano multi-scale hierarchical porous structure on the surface of Inconel718 nickel-base superalloy by one-step method

A new high-efficiency composite process consisting of laser machining and abrasive belt grinding was proposed to prepare multi-scale graded microstructures on the surface of Inconel718 nickel-base superalloy for aviation. The scheme is based on the machining characteristics of abrasive belt grinding, low damage molding and high-efficiency grinding and polishing, the effective combination of ultrashort pulse laser-induced surface microstructure growth, and the thermal effect in the process of high-energy beam machining, so as to realize the efficient preparation of hierarchical microstructure. In the one-step forming process, the accuracy of the material surface is ensured by abrasive belt grinding. The porous microstructure on the surface is catalyzed by the thermal effect produced by the high-energy beam laser. The scale of the porous structure is 3 µm–6 µm, the pore surface will generate nanoparticles, the size is below 100 nm, and dense nanoparticles will be generated on the surface. The porous structure can be super hydrophilic and adsorbed to form a liquid membrane. The formation of rib-like microstructures on the surface induced by ultrashort pulse laser makes the liquid film have directional spreading properties. Rib-like microstructure height is 50 µm–150 µm and it can be adjusted by setting the scanning line width. The one-step method for preparing hierarchical microstructures proposed in this study can efficiently process large-area microstructure surfaces with different wetting properties. • The porous structure, nanoparticles, and rib-like bulges can be efficiently fabricated. • The microstructure can be easily regulated.

Numerical simulations of grinding force and surface morphology during precision grinding of leucite glass ceramics

• A force model of grinding of leucite glass ceramics is developed. • A surface morphology model of grinding of leucite glass ceramics is developed. • Elastic-to-plastic and brittle-to-ductile transitions are considered in the models. • The predicted errors of two models are within 10% and 15%. Leucite glass ceramics are high-performance denture materials due to their high mechanical strength, excellent light transmittance, and excellent biocompatibility. Glass-ceramic denture must be processed using precision grinding technology to achieve a satisfactory surface integrity. To understand the contact interaction between the abrasives and workpiece, a theoretical model of grinding force during grinding of leucite glass ceramics was developed by considering elastic-to-ductile transition depth, brittle-to-ductile transition depth, strain rate effect, and random distributions of the abrasive position and size. In addition, a surface morphology model was developed to understand the material removal and deformation behaviors during grinding of leucite glass ceramics, which considered the brittle-to-ductile transition depth, elastic recovery, and random distributions of the abrasive position and size. The mechanical properties of leucite glass ceramics used in the models were measured by nanoindentation and nanoscratch tests. Grinding experiments of leucite glass ceramics were performed to verify the accuracy of the models, and the results showed that the predicted errors of the force and surface morphology models were within 10% and 15%, respectively. Both theoretical and experimental results demonstrated that small abrasive size, low feed speed, small grinding depth, and high grinding speed were beneficial to improving the surface quality, and large abrasive size, low feed speed, small grinding depth, and high grinding speed were beneficial to decreasing the grinding force. The results will provide a theoretical guidance for optimizing process parameters during high-efficiency and precision grinding of hard and brittle solids. Graphical Abstract .

Friction and wear behavior of diamond film with adjustable grain size against silicon carbide in different tribological tests

Efficient processing of silicon carbide (SiC) is still challenging due to its high hardness. Microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films were deposited on SiC ceramics by controlling methane concentration and gas pressure. Two different tribological tests were executed on rotating ball-on-plates and linear reciprocating tribometers. The morphology and the elemental composition of abrasion marks and ball surface were evaluated to determine the main wear mechanism. We found that the MCD film had high grinding efficiency, leading to the roughness Ra of 68 nm on the surface of the SiC ceramic ball, while NCD film obtained the lower roughness although there was a lower grinding efficiency. Both diamond films had no damage, but a layer of SiC debris was covered on the NCD. The efficiency of MCD was 20 times that of NCD in terms of wear rate. The grinding efficiency of the reciprocating friction test was only half that of the rotary test due to the unidirectional axial force. Diamond films with different grain sizes are expected for different applications for SiC processing, such as thinning, coarse grinding, and fine grinding.

Heat transfer performance assessment of abrasive phyllotaxy arrangement in internal cooling grinding

The traditional flood cooling method is hard to dissipate the massive amount of heat accumulated in the grinding zone during the high-efficiency grinding process, which easily causes burnout of the workpiece that limits the increase of the processing efficiency. Employing an abrasive phyllotaxy arrangement and an internal cooling grinding wheel (ICGW) can augment the heat transfer of the coolant in the grinding zone to lower the grinding temperature. An abrasive phyllotaxy arrangement internal cooling grinding wheel that is a combination of an ICGW and abrasive phyllotaxy arrangement was proposed in this study. To optimize geometric dimensions and phyllotaxy coefficient of the abrasive phyllotaxy arrangement ICGW, simulation and experimental investigations were carried out to explore the effects of coolant (water-based ILs-MWCNTs/MoS2 hybrid nanofluids), grinding wheel diameters, and phyllotaxy growth coefficient on the heat transfer capability of the wheels. Within a specific range, the ICGWs with a smaller diameter and larger phyllotaxy growth coefficient show an advantage in fluid flow and heat transfer. Experimental results exhibit that, compared with the typical orderly arrangement, the grinding temperature and surface roughness of the ICGWs with the phyllotaxy pattern was reduced by about 20% and 50%, respectively. Under the same phyllotaxis coefficient, the grinding temperature and surface roughness obtained by the ICGWs with a smaller diameter were reduced by 10% and 22.3%, respectively. The residual compressive stress was elevated by 10.94%.

Heat flux distribution model and transient temperature field analysis in grinding of helical raceway

To solve the problem of low processing efficiency of screw helical raceway by using high-efficiency grinding technology, this paper carried out theoretical, simulation, and experimental analyses on the grinding temperature which mainly affects the selection of high-efficiency grinding process parameters. First, based on the distribution characteristics of the grinding allowance of the screw helical raceway, the analysis shows that the geometry of the grinding contact area is trapezoidal. Then, based on the existing triangular heat flux distribution model of the rectangular contact area, two heat flux distribution models of the triangle and the concave triangle are proposed according to the characteristics of the trapezoidal contact area. Finally, the plane grinding experiment was carried out to correct the simulation parameters, and the modified simulation parameters were used to predict the grinding temperature of the screw raceway, so as to achieve the maximum removal efficiency and avoid burns. The analysis results show that the highest temperature in the grinding area is on the lowest point of the helical raceway, and the temperature and temperature gradient in the grinding area obtained by using the concave triangular heat flux distribution model are the highest. By comparing the process parameters for the onset of grinding burns predicted by simulation and experimentally, the temperature predicted by the concave triangle heat flux distribution model in the trapezoidal contact area is higher than the actual temperature, while the temperature predicted by the triangle heat flux distribution model in the trapezoidal contact area is lower than the actual temperature.

High Accuracy and High Efficiency Grinding of Cemented Carbide with Ultrafine Bubbles Coolant

High Accuracy and High Efficiency Grinding of Cemented Carbide with Ultrafine Bubbles Coolant

Optimization of hydrodynamic properties of structured grinding wheels based on combinatorial bionics

Undesirable hydrodynamic properties are inevitable in the traditional grinding process, which often provides a harsher lubrication environment. This paper introduces combinatorial bionics to optimize the hydrodynamic properties of grinding tools innovatively. Two bionic prototypes (phyllotaxis arrangement and fish scale) with special hydrodynamic properties are organically integrated to help design a combinatorial bionic grinding wheel (CBGW). The CBGW can more effectively inhibit the adverse effects of air turbulence on the grinding process and maintain a higher useful flow rate with a maximum improvement rate of 290.47%. This study enhances the effectiveness of grinding fluids from the perspective of grinding wheel structure and provides an excellent tribological basis for green and high-efficiency grinding.

Curvature effect induced cutting stress field offset and its influence on the damage of hard and brittle materials

Although many studies on the initiation of glass cracks under contact loads were carried out, specific problems arising under complex machining conditions remain poorly understood. In order to clarify the influence of particle trajectory curvature change on material grinding mechanism, a theoretical model of trochoid curvature radius was established, and the main factors affecting trochoid curvature were identified (moving circle radius R, spindle speed n and feed speed vw). Different curvature trochoid scratches were obtained by the experiment of trochoid feed scratches on quartz glass. The experimental results show that the scratch damage of the maximum curvature segment is larger than that of the minimum curvature segment. With the increase of trochoid curvature, material damage inside the scratch is more significant than outside. In order to further explain the distribution characteristics of trochoid scratches. Numerical simulation and theoretical analysis were used to verify the relationship between damage difference and curvature on both sides of the trochoid feed scratch groove. The curvature effect of trochoid feed scratch damage is proposed for the first time, which is used to explain stress field migration and damage distribution caused by trochoid curvature characteristics. This study further supplements and clarifies the removal mechanism of hard and brittle materials, which has theoretical guiding significance for quartz glass high-efficiency and controllable precision grinding.

Development of In-Process Temperature Measurement of Grinding Surface with an Infrared Thermometer

Heat generation is a critical issue in grinding. If the grinding point generates significant heat, dimensional and shape accuracy may decrease due to thermal deformation, and the machined surface may deteriorate due to grinding burn. Therefore, monitoring the temperature during grinding is important to obtain ideal machining results. In this research, we develop a new method to measure the grinding surface and grinding wheel surface temperature during in-process machining. The proposed method measures the temperature of the grinding surface through small holes in a rotating grinding wheel. Using this method, we measured the temperature of the grinding surface during the dry grinding of carbon fiber reinforced plastics (CFRP). Temperature of the grinding surface was measured every 1/4 rotation of the grinding wheel at any depth of cut, assuming precision grinding, rough grinding, and high-efficiency grinding. The measurement value changed depending on the temperature measurement position of the infrared thermometer from numerical analysis of the grinding surface temperature. We also found that when the cut depth was small, the temperature, including the surface of the workpiece before machining, was measured at a specific temperature measurement position. The newly developed temperature measurement method was capable of in-process measurement of the grinding surface temperature and of detecting temperature rise when the grinding wheel was clogged.