Grinding Depth Research Articles

The Effects of Process Parameters on Workpiece Roundness in the Shoe-Type Centerless Grinding Operation for Internal Raceway of Ball Bearings

One of the most important indices of bearing raceway, roundness, has an important influence on the life and performance of the bearing. Currently, shoe-type centerless grinding (STCG) is a core process for the fabrication of the raceway surface. Some researchers have carried out studies in this field; however, the reason and extent of the influence of process parameters on the workpiece roundness in the STCG operation for the internal raceway of the 6208 ball bearings are not clear up to now. In this paper, new research on the effects of process parameters on workpiece roundness in the STCG operation for the internal raceway of the 6208 ball bearings is presented. The influence of the angular placement of the two shoes, as well as the technology parameters including the offset between the rotational centers of the workpiece and the magnetic drivehead (e), the normal feed rate (Snf), the speed of the workpiece (nw), and the grinding depth (af), on the roundness of the raceway surface were investigated both theoretically and experimentally to solve the difficulties in the STCG operation to ensure the roundness of the raceway surface. Based on the research results, a guideline for selecting initial process parameters is introduced to ensure the roundness of the bearing raceway in the STCG operation for the internal raceway of 6208_ball bearings on the 3MK136B grinder.

Research on the machining mechanism of AISI 304 ultrasonic vibration assisted grinding

Compared with conventional grinding (CG), ultrasonic vibration assisted grinding (UVAG) has more prospects and competitiveness in processing AISI 304. Due to the change of strength of materials, when the vibration is superimposed on the workpiece, the mechanism of ultrasonic assisted machining is different from that of tool ultrasonic assisted machining. Therefore, this article proposes a workpiece vibration grinding device suitable for UVAG to study the corresponding grinding mechanism. The vibration characteristics of workpiece ultrasonic generator were discussed based on finite element simulation and the vibration situation of the device was tested with instruments to verify the accuracy of the simulation. Meanwhile, the machining mechanism of workpiece ultrasonic vibration was studied through grinding comparative experiments. The experiment showed that the displacement curve of the output end of the ultrasonic vibration of AISI 304 with time could be approximated to a sine wave and there was no other clutter. As the amplitude percentage of the ultrasonic generator increased, the output amplitude of the transducer showed an increasing trend. The ultrasonic amplitude and the amplitude percentage of ultrasonic generator approximately follow a linear relationship. The grinding force decreased with the increase of spindle speed and amplitude, and increased with the increase of feed rate and grinding depth. Compared with conventional grinding force, the grinding force of tangential ultrasonic vibration assisted grinding (TUVAG) decreased by about 29 %, while the grinding force of radial ultrasonic vibration assisted grinding (RUVAG) decreased by about 28 %. Under the action of ultrasound, the workpiece obtained better surface morphology. Under processing conditions of vw = 25 mm/min, ap = 0.01 mm, n = 2000r/min, A = 8 μm, f = 20000 Hz, the minimum surface roughness Ra of TUVAG is 0.51, followed by RUVAG with Ra = 1.02, while the surface roughness Ra of CG is the worst at 1.56 due to grinding burns.

Numerical Investigation on the Effects of Grain Size and Grinding Depth on Nano-Grinding of Cadmium Telluride Using Molecular Dynamics Simulation.

Cadmium telluride (CdTe) is known as an important semiconductor material with favorable physical properties. However, as a soft-brittle material, the fabrication of high-quality surfaces on CdTe is quite challenging. To improve the fundamental understanding of the nanoscale deformation mechanisms of CdTe, in this paper, MD simulation was performed to explore the nano-grinding process of CdTe with consideration of the effects of grain size and grinding depth. The simulation results indicate that during nano-grinding, the dominant grinding mechanism could switch from elastic deformation to ploughing, and then cutting as the grinding depth increases. It was observed that the critical relative grain sharpness (RGS) for the transition from ploughing to cutting is greatly influenced by the grain size. Furthermore, as the grinding depth increases, the dominant subsurface damage mechanism could switch from surface friction into slip motion along the <110> directions. Meanwhile, as the grain size increases, less friction-induced damage is generated in the subsurface workpiece, and more dislocations are formed near the machined groove. Moreover, regardless of the grain size, it was observed that the generation of dislocation is more apparent as the dominant grinding mechanism becomes ploughing and cutting.

Grinding Characteristics of MoS2-Coated Brazed CBN Grinding Wheels in Dry Grinding of Titanium Alloy

As an important green manufacturing process, dry grinding has problems such as high grinding temperature and insufficient cooling capacity. Aiming at the problems of sticking and burns in dry grinding of titanium alloys, grinding performance evaluation of molybdenum disulfide (MoS2) solid lubricant coated brazed cubic boron carbide (CBN) grinding wheel (MoS2-coated CBN wheel) in dry grinding titanium alloys was carried out. The lubrication mechanism of MoS2 in the grinding process is analyzed, and the MoS2-coated CBN wheel is prepared. The results show that the MoS2 solid lubricant can form a lubricating film on the ground surface and reduce the friction coefficient and grinding force. Within the experimental parameters, normal grinding force decreased by 42.5%, and tangential grinding force decreased by 28.1%. MoS2 lubricant can effectively improve the heat dissipation effect of titanium alloy grinding arc area. Compared with common CBN grinding wheel, MoS2-coated CBN wheel has lower grinding temperature. When the grinding depth reaches 20 μm, the grinding temperature decreased by 30.5%. The wear of CBN grains of grinding wheel were analyzed by mathematical statistical method. MoS2 lubricating coating can essentially decrease the wear of grains, reduce the adhesion of titanium alloy chip, prolong the service life of grinding wheel, and help to enhance the surface quality of workpiece. This research provides high-quality and efficient technical support for titanium alloy grinding.

Robotic compliant grinding of curved parts based on a designed active force-controlled end-effector with optimized series elastic component

High-accuracy, fast-response, and low-overshoot force control are important to guarantee the material removal accuracy and surface quality of robotic compliant grinding. In order to achieve the above target, this study develops an active compliant force-controlled end-effector based on a series elastic actuator for the robotic grinding of curved parts. Firstly, a decoupled robotic grinding system composed of an industrial robot and an end-effector is developed, and a novel force-controlled end-effector is designed by adding an elastic component between the servo motor and the load to improve compliance. Secondly, the influences of the elastic component and grinding tool stiffness on the stability of the force-controlled end-effector system are analyzed by establishing a contact model of the compliant end-effector and the transfer function of the entire force control system. Then, the stiffness of the grinding tool and the elastic component are optimized with full consideration of the system cutoff frequency and the end-effector compliance. To improve the force tracking accuracies of the developed compliant end-effector, a proportional-integral (PI) controller with first-order differential force feedforward control is designed. Finally, grinding experiments are conducted for verification. The effects of spring stiffness and grinding tool stiffness on the force control system are tested, which match well with the theoretical analysis. Grinding results show that the maximum force control error of the compliant force-controlled end-effector is decreased by 70% compared to that of the rigid force-controlled end-effector, and the overshoot of the force control is reduced from 30% to almost 0 under the same response speed. The maximum and average absolute grinding depth errors using the designed end-effector are reduced by 57.2% and 58.6%, respectively, compared with those of the traditional rigid end-effector, and the average surface roughness of the finished part is reduced by 19.2%. Which demonstrates the effectiveness and advantages of the proposed compliant force-controlled end-effector.

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.

Experimental study on ultrasonic vibration assisted grinding of GCr15SiMn bearing steel

Many problems of GCr15SiMn high-carbon chromium bearing steel have been found in the ordinary grinding (OG) process. Aiming at the problems of high grinding force, low residual compressive stress and low surface quality, ultrasonic machining technology is combined with OG. The test of ultrasonic vibration assisted grinding (UVAG) GCr15SiMn high carbon chromium bearing steel is carried out. The residual stress, surface roughness, grinding force, and surface morphology are analyzed by changing machining parameters. The research showed that as the grinding depth and feed speed become larger, the grinding force increased, when the spindle speed rises, the grinding force becomes smaller. In the test range, with the ultrasonic amplitude from small to large, the grinding force from large to small. The ultrasonic grinding force is 27.8% lower than that of OG. The surface roughness increases with increasing grinding depth and feed speed and decreases with increasing spindle speed and ultrasonic amplitude, and at an amplitude of 6 μm, the surface roughness is reduced by 27% compared to OG. When the feed speed and grinding depth are lowered or the ultrasonic amplitude is increased, the surface residual compressive stress is increased. Compared to OG, it is increased by more than 13.5% under the same parameters. At the same time, the phenomenon of burrs and surface tears can be reduced, and the surface quality of the workpiece becomes better.

Burr formation mechanism and morphological transformation in grinding of nickel-based superalloy honeycomb cores under ice freezing and MQL conditions

Nickel-based superalloy honeycomb core (NBSHC) is extensively used in aerospace field due to the light weight, high specific strength and high temperature resistance. The burrs of NBSHC are extremely prone to be formed during machining and the insufficient welding strength or false welding between NBSHC and skin is generated because of the large or unreasonable burr morphology, resulting in premature failure of the parts. In this work, a novel method of ice freezing combining with minimum quantity lubrication (MQL) was proposed to grind NBSHC to improve the burr morphology and size. The burr formation mechanisms of NBSHC under ice freezing and MQL conditions were revealed by single abrasive particle grinding cell wall and verified by grinding experiments. The grinding force, burr morphology transformation mechanisms and size were investigated in-detail by experiments combining with FEM results. The results indicated that MQL and ice freezing decreased the plastic flow property of material by reducing the temperature and friction of NBSHC, thereby promoting the transformation of burr size from large into micro, and the burr shape from long strip into block. Decreasing grinding depth can also improve the burr morphology by decreasing the volume of plastic flow material. The improving effects of full of ice freezing were better than MQL for NBSHC grinding. The machining efficiency under full of ice combining with MQL was 3 times of that under quasi-dry grinding. These findings are significant for improving the machining quality and exploring the burr morphology transformation of NBSHC.

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.

Enhanced Mechanical Properties of QAl9-4 Aluminum Bronze for High-Speed-Rail Brake Systems with a Pulsed Magnetic Field.

To improve the mechanical properties and wear resistance of QAl9-4 aluminum bronze alloy parts of high-speed rail brake calipers, the solid aluminum bronze alloy was treated with a pulsed magnetic field in which the magnetic induction intensity was 3T at room temperature. After that, a tensile test and a friction and wear test were carried out on the alloy. The results indicate that the magnetic field promotes the movement of low-angle grain boundaries less than 2° and splices to form subcrystals or fine crystals, which reduces the mean grain size of the alloy. The disordered dislocation changed into a locally ordered dislocation line, the dislocation distribution became uniform, and the dislocation density increased, which simultaneously improved the alloy's tensile strength and elongation. The elongation increased by 10.2% compared with that without the magnetic field. The increase in strength can provide strong support for the wear-resistant hard phase, and the enhancement of plasticity can increase the alloy's ability to absorb frictional vibration. Therefore, it was hard for cracks to form and extend, and the specimen's average friction coefficient was reduced by 22.05%. The grinding crack width and depth decreased, the wear debris became more uniform and fine, and the alloy's wear resistance increased.

Study on surface quality of CNTs/2009Al composites in grinding process with a volume fraction ratio of 3%

Composite materials made of aluminum-based carbon nanotubes (CNTs/Al) are often employed in industries like aerospace and national defense that place a high priority on material processing accuracy at the material’s surface. The most popular machining technique for enhancing the surface quality of materials is grinding. This paper built a prediction model for the surface roughness of CNTs/2009Al composites and identified the process of micro-grinding. Using the ABAQUS software, a non-uniform finite element simulation model of the single abrasive grain grinding process of CNTs/2009AL composites was created. An electroplated diamond grinding rod with a diameter of 2 mm was used in the micro-grinding experiment on the CNTs/2009Al composite, and the impact of the grinding parameters on the quality of the machined surface was examined. According to the findings, the feed speed has the least impact on the material’s surface roughness, whereas the spindle speed and grinding depth both have a significant impact. The measurement of the minimal roughness is 0.117 m. A shallower grinding depth, a lower feed rate, and a correspondingly higher spindle speed should be used in order to provide a superior surface quality. According to the prediction model of micro-grinding surface roughness and laser confocal microscope scanning, the primary phenomena of CNTs in the grinding process include pull-out, fracture, and elastic deformation.

Tribological Mechanism of Graphene and Ionic Liquid Mixed Fluid on Grinding Interface under Nanofluid Minimum Quantity Lubrication

Graphene has superhigh thermal conductivity up to 5000 W/(m·K), extremely thin thickness, superhigh mechanical strength and nano-lamellar structure with low interlayer shear strength, making it possess great potential in minimum quantity lubrication (MQL) grinding. Meanwhile, ionic liquids (ILs) have higher thermal conductivity and better thermal stability than vegetable oils, which are frequently used as MQL grinding fluids. And ILs have extremely low vapor pressure, thereby avoiding film boiling in grinding. These excellent properties make ILs also have immense potential in MQL grinding. However, the grinding performance of graphene and ionic liquid mixed fluid under nanofluid minimum quantity lubrication (NMQL), and its tribological mechanism on abrasive grain/workpiece grinding interface, are still unclear. This research firstly evaluates the grinding performance of graphene and ionic liquid mixed nanofluids (graphene/IL nanofluids) under NMQL experimentally. The evaluation shows that graphene/IL nanofluids can further strengthen both the cooling and lubricating performances compared with MQL grinding using ILs only. The specific grinding energy and grinding force ratio can be reduced by over 40% at grinding depth of 10 μm. Workpiece machined surface roughness can be decreased by over 10%, and grinding temperature can be lowered over 50 ℃ at grinding depth of 30 μm. Aiming at the unclear tribological mechanism of graphene/IL nanofluids, molecular dynamics simulations for abrasive grain/workpiece grinding interface are performed to explore the formation mechanism of physical adsorption film. The simulations show that the grinding interface is in a boundary lubrication state. IL molecules absorb in groove-like fractures on grain wear flat face to form boundary lubrication film, and graphene nanosheets can enter into the grinding interface to further decrease the contact area between abrasive grain and workpiece. Compared with MQL grinding, the average tangential grinding force of graphene/IL nanofluids can decrease up to 10.8%. The interlayer shear effect and low interlayer shear strength of graphene nanosheets are the principal causes of enhanced lubricating performance on the grinding interface. EDS and XPS analyses are further carried out to explore the formation mechanism of chemical reaction film. The analyses show that IL base fluid happens chemical reactions with workpiece material, producing FeF2, CrF3, and BN. The fresh machined surface of workpiece is oxidized by air, producing NiO, Cr2O3 and Fe2O3. The chemical reaction film is constituted by fluorides, nitrides and oxides together. The combined action of physical adsorption film and chemical reaction film make graphene/IL nanofluids obtain excellent grinding performance.

Grinding damage in the fabrication of polycrystalline cubic boron nitride micro-drill

Micro superhard cutting tool such as polycrystalline cubic boron nitride (PCBN) tool are increasingly demanded in high-end manufacturing field. The grinding is a widely used technology in the manufacture of superhard micro-tools, but its grinding damage is often difficult to control. In order to improve the grinding quality of superhard micro-tools, it is necessary to further understand the damage behavior during tool grinding process. This study aims to reveal the damage form and damage formation mechanism in the grinding process of PCBN micro-drills. The PCBN micro-drill grinding experiment is conducted under different process parameters, and the morphology characteristics of the micro-drill surface and cutting edge are observed and analyzed. The influence of grinding process parameters on the grinding quality of PCBN micro-drill is quantitatively investigated. The results indicate that, the grinding damage of PCBN micro-drill is mainly manifested as micro chipping and micro fracture of the cutting edge, material adhesion on the chisel edge, and micro cracks, micro pits and micro scratches on the grinding surface. For the ground surface of flank and helical flute of PCBN micro-drill, the material removal mechanisms of plastic removal and brittle removal work together. The material in the area with more binder inclusions is removed by plastic removal mode, and the material brittleness removal mode mainly includes cleavage brittleness removal and intergranular brittleness removal. The edge impact fracture brings grinding damage to the main cutting edge of PCBN micro-drill. The CBN grains at the fracture surface mainly undergo cleavage fracture, while the fracture of the binder occurs in the form of micro pit aggregation. The reduction of grinding depth and feed rate will lead to the decrease in the surface roughness of flank and helical flute, the cutting edge radius, and the edge chipping width, thus improve the grinding quality of PCBN micro-drill. These findings contribute to expand the understanding of process characteristics for grinding PCBN micro-tools, and thus to restrain the grinding damage and improve the grinding quality of micro-tools.

Mechanism and enhanced grindability of cryogenic air combined with biolubricant grinding titanium alloy

Grinding is an essential method for ensuring the machining accuracy and surface quality of difficult materials, such as aerospace titanium alloys. However, the deterioration of workpiece surface integrity due to thermal damage is the technical bottleneck of titanium alloy grinding. Therefore, a new enabling grinding technology for cryogenic air combined with a biolubricant is proposed. The introduction of cryogenic air leads to fundamental changes in the physical properties and lubrication mechanism in the grinding zone. On this basis, the formulas between the cryogenic air temperature and biolubricant temperature, kinematic viscosity, and surface tension coefficient are established. Under the same grinding parameters, compared with dry grinding, the normal force, tangential force, specific grinding energy, friction coefficient, temperature, and surface roughness value of cryogenic air minimum quantity lubrication decrease by 47.6%, 44.3%, 45.1%, 19.8%, 43.9%, and 46.3%, respectively. Then, the influence law of single and multiple factors on the grinding effect is discussed. When the peripheral speed, feed speed, and grinding depth are 30 m/s, 6 mm/s, and 30 µm, the optimal combination of factor parameters is a cryogenic air temperature of − 50 °C, an air pressure of 0.4 MPa, and nozzle inclination angle of 16°. Furthermore, on the basis of the multifactor orthogonal experiment, the quantitative mapping relationship between different grinding and influence factors is investigated to achieve optimal workpiece surface quality. This research provides a new effective method for improving the high surface integrity of grinding titanium alloys by using the cryogenic air minimum quantity lubrication method.

Силовой анализ процесса резания единичным зерном сферокорунда при шлифовании древесины

The productivity of the wood grinding process can be increased by using abrasive wheels with spherical corundum grains. They also expand the area of application of rigid abrasive instruments by reducing soiling and eliminating burns on the treated surface. The studies revealed several advantages of the abrasive wheels over sanding paper: very precise processing, achievement of the desired grade of the treated surface, high durability of the instrument, and low cost. A force analysis of a grinding surface with micro-cuttings made of spherical corundum grains was performed depending on the degree of its wear. The results revealed that chip removal by the spherical corundum grains was possible only under certain conditions when the cutting edges of the grains were exposed. Besides, the theoretical dependencies of forces in micro-cutting were obtained from every principal condition for the process of grinding wood and wooden materials: properties of the spheres, treatment modes, and material-related factors. The special properties were analyzed by the chip formation process and self-sharpening conditions of the spherical corundum wheels. The grain size had the greatest influence on the thickness of chips which were cut by one grain. The grain content and bonding, like other properties of the internal volumetric structure, had a less substantial impact. The abrasive tool characteristics must complement the processed material, such as grain size, hardness, and structure. On the other hand, spherical corundum has optimal physical and mechanical properties for grinding, particularly the thickness of the grain’s edges, which primarily determine the material’s tensile strength. The grinding depth and feed rate mostly define the parameters of the grinding performance of wood and wood-based materials. An increase in those leads to a rise in cutting forces, roughness of the ground surface, a reduction in the grinding length over the period of the wheel’s durability, and the grinding coefficient. If the grinding depth and feed rate are constant, the performance can be improved by increasing the cutting rate. For citation: Sergeevichev A.V., Sokolova V.A., Mikhailova A.E., Ovcharova E.O., Voinash S.A. Force Analysis of a Single Grain Cutting Process in Wood Grinding Using Spherical Corundum. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 140–154. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-140-154

Grinding performance study of CF/epoxy and CF/PEEK composites

AbstractIn order to distinguish the grinding performance of the thermoset and thermoplastic carbon fiber‐reinforced plastic (CFRP) composites, carbon fiber‐reinforced epoxy resin (CF/epoxy) and carbon fiber‐reinforced poly‐ether‐ether‐ketone (CF/PEEK) composites were employed in this study. Different process parameters were set to grind the two materials. Then the surface morphologies and roughness of the workpieces with different process parameters were observed and measured. Experimental results indicated that the grinding forces were positively correlated with the grinding depth and feed speed, and negatively correlated with the wheel speed. The grinding depth was the main influencing factor of the maximum temperature of the grinding. The heat distribution of the grinding process was dependent on the fiber direction. In addition, the chip formation mechanism of CF/epoxy and CF/PEEK were investigated. Compared with CF/epoxy, the grinding forces and temperature were higher and the wheel was more prone to be clogged under the same grinding parameters, indicating that it was more difficult to process CF/PEEK. However, the surface quality of CF/PEEK with high ductility was much better than CF/epoxy.

에나멜 동선 피막 제거를 위한 가공부하 기반 연삭가공공정 적응제어기술

A hairpin motor is a type of motor that is used for driving an eco-friendly car. Unlike a conventional coil-winding motor, hundreds of hairpins formed by an enameled copper wire with a rectangular cross section comprise a stator to improve the driving efficiency by maximizing a coil drip rate. With the increased use of the hairpin motor, there has been an increased interest in manufacturing techniques and automated systems of the hairpin motor. Enamel coating removal is one of the major processes of hairpin motor production; enamel coating at the end of the hairpin should be removed to connect the hundreds of hairpins by using the welding process. Grinding is one of the machining processes used for removing the enamel coating. This study proposed an adaptive control method for the grinding process to improve the efficiency and quality of the enamel coating removal process. Grinding depth is maintained during machining by controlling the vertical position of the spindle based on driving torque. A lab-scale grinding machine including a sensory system for adaptive control is developed and used to verify the performance of the proposed method.

Engineering attributes of alkali-activated mortars containing ceramic tiles waste as aggregates replacement: Effect of high-volume fly ash inclusion

Fast depletion of the natural aggregates and an ever-increasing carbon footprint in environment has enforced humanity to take an immediate remedial measure. Meanwhile, the wastes generated from ceramic materials by various industries worldwide became responsible for growing landfill problems. Several alkali-activated mortars mortars containing ceramic tiles waste as natural aggregates replacement have been designed and evaluated to assess the effectiveness of such waste on the engineering characteristics, such as compressive strength, drying shrinkage, abrasion resistance and water absorption performance of the obtained mortars. The prepared mortars enclosed high volume Fly Ash (FA), Ceramic Tiles Waste (CTW) and Ground Blast Furnace Slag (GBFS). It has been observed that the use of 100% of CTW as fine aggregates replacement was shown to achieve strengths comparable to the control specimen, whereas the inclusion of high volume of FA contents as GBFS substitute in the proposed mix design was discerned to affect significantly on their early strength, thus enhanced the durability performance in term of reducing the total drying shrinkage. However, the results showed that the porosity and abrasion resistance are negatively affected due to increasing FA level. The grinding depth and waster absorption percentage of the mortars was found to increase with the increase of FA content as GBFS replacement.

Acoustic emission identification of wheel wear states in engineering ceramic grinding based on parameter-adaptive VMD

In engineering ceramic grinding, the wheel wear states have an important influence on the processing efficiency and grinding quality. To address the difficulty of online monitoring of wheel wear states, a signal reconstruction method based on parameter-adaptive variational modal decomposition was proposed. Experiments on the entire life cycle of the grinding wheel were performed, and the wear states were classified based on the observed surface morphologies of the wheel and workpiece. Subsequently, acoustic emission signals were collected by nodes, and high correlation frequency bands were chosen and reconstructed. The signal features were extracted, and the wear states were identified based on a random forest optimization feature combination, finally. In this study, taking alumina ceramic as an example, eight groups of single-factor experiments were designed based on cumulative grinding depth to determine the optimal linear speed of the grinding wheel, worktable moving rate, and other process parameters. A total of 160 groups of AE signal samples were obtained. The results show that feature extraction by frequency bands can better reflect the changes in the grinding wheel wear states than the overall signal. In addition, optimization feature combinations based on the bands after decomposition, filtering, and reconstruction can divide and identify the various wear states more effectively. The comprehensive identification accuracy reached 90.6%. The accuracy of identifying the severe wear state reached 100%. Thus, the proposed method provides theoretical guidance for the practical industrial applications of online monitoring of wheel wear states.

Surface topography of cylindrical precision grinding based on multi-source information fusion

In this study, spindle precision bearings and rotary vector (RV) reducer thin-walled bearings were taken as research objects. Based on the analysis of the metamorphic layer of bearings, the multidimensional research on the surface topography of parts by multisource information fusion (grinding force, grinding temperature, grinding strain, grinding vibration, and grinding acoustic emission (AE)) was put forward. The research shows that there are “dark layers” in the outer ring and inner ring of spindle precision bearings, and “white layers” and “dark layers” in the outer ring and inner ring of RV reducer thin-walled bearings. Feed speed has the greatest influence on grinding force, wheel speed, and grinding depth have the greatest influence on grinding temperature, wheel speed has the greatest influence on grinding strain, feed speed, and wheel speed have the greatest influence on grinding vibration, and workpiece speed has the greatest influence on grinding AE. When the grinding force is minimum ( x-axis: 1.3 N, y-axis: 0.9 N); the grinding temperature is highest (110.8°C), the grinding strain is maximum (46.6%), the grinding vibration is maximum (vibration range: 400 m/s2–400 m/s2) and the grinding AE is maximum (variation range: 2 V–1 V), the surface topography is most prominent (Ra: 0.97 μm). Grinding wheel speed and grinding depth have the greatest influence on surface topography, followed by feed speed, while workpiece speed has less influence.