Conventional Grinding Methods Research Articles

Solvent free green synthesis of tri-substituted imidazoles catalyzed by multi-doped ZnO-GCN nanocomposites

Applying the method of grinding, a series of 2,4,5-tri-substituted imidazole derivatives have been synthesised in highly satisfactory yields without the need for a solvent. In which grinding a mixture of benzoin or benzil and verities of the aldehydes in the existence of ammonium acetate, as a nitrogen source is successfully synthesized by using the efficient multi-doped ZnO- graphitic carbon nitride (g-C3N4) nanocomposite catalyst (Bi (4 %), Cr(1 %)-doped ZnO-GCN). In this protocol, comparative studies of the single-pot synthesis of 2,4,5-trisubstituted imidazole compounds are performed by using conventional and mechanochemical grinding methods with and without Bi-Cr-doped ZnO-GCN nanocomposite catalyst. All synthesised compoundswere characterised by their melting points, 1HNMR, and 13CMR spectra. In these studies, we found that grinding methodology with Bi-Cr-doped ZnO-GCN nanocomposite catalyst enhanced the reaction efficiencies with a short reaction time, excellent products, a cleaner reaction, and an easy workup. Additionally, the reaction follows green chemistry guidelines because it just requires the grinding of the substrates and catalyst in the absence of a solvent. Furthermore, the final product is simply purified by recrystallization as well as whenever needed using the column chromatography process.

INVESTIGATION OF ENERGY - TECHNOLOGY DEVELOPMENT IN ULTRA FINE GRINDING

Ultra-fine grinding refers to the process of reducing materials to extremely small particle sizes, typically in the micron or submicron range. It is commonly used in various industries such as mining, pharmaceuticals, ceramics, and chemicals, where the production of fine particles with specific properties is required.
 Energy plays a significant role in ultra-fine grinding processes. The reduction of materials to such small sizes requires a considerable amount of energy input. The energy consumption in ultra-fine grinding is typically higher compared to conventional grinding methods due to the higher surface area and increased particle-particle interactions.
 In the mining sector, with the depletion of high-grade ore deposits, it has become a necessity to operate very low-grade ore deposits with very small particle liberation sizes. In the enrichment of these ores, most of the energy required is spent on grinding. In micronized grinding, conventional mills (such as rod and ball mills) lose their efficiency and become uneconomical. 
 most of the energy spent in conventional mills is used directly in size reduction, and a significant portion is lost as heat and sound without doing any useful work (size reduction). In addition, for grinding below 75 µm , the efficiency of conventional mills is greatly reduced (energy consumption increases excessively), and grinding becomes uneconomical. 
 In this study, alternative fine and ultrafine grinding mills for ore dressing plants are introduced, and information about their working principles is presented. Unlike other studies, information on particle and grinding energy calculations is given. The reasons for the lack of a theory or model to perform newly developed calculations for ultrafine grinding theories are tried to be explained.

Research on a Method of Robot Grinding Force Tracking and Compensation Based on Deep Genetic Algorithm

In the grinding process of complex-shaped cast workpieces, discrepancies between the workpiece’s contours and their corresponding three-dimensional models frequently lead to deviations in the machining trajectory, resulting in instances of under-grinding or over-grinding. Addressing this challenge, this study introduces an advanced robotic grinding force automatic tracking technique, leveraging a combination of deep neural networks and genetic algorithms. Harnessing the capability of force sensing, our method dynamically recalibrates the grinding path, epitomizing truly flexible grinding. Initially, in line with the prerequisites for force and pose tracking, an impedance control strategy was developed, integrating pose deviations with force dynamics. Subsequently, to enhance steady-state force tracking, we employed a genetic algorithm to compensate for force discrepancies caused by positional errors. This was built upon the foundational concepts of the three-dimensional model, impedance control, and environmental parameter estimation, leading to an optimized grinding trajectory. Following tracking tests, it was observed that the grinding’s normal force was consistently controlled within the bracket of 20 ± 2.5 N. To further substantiate our methodology, a specialized experimental platform was established for grinding complex-shaped castings. Optimized strategies were employed under anticipated forces of 5 N, 10 N, and 15 N for the grinding tests. The results indicated that the contact forces during the grinding process remained stable at 5 ± 1 N, 10 ± 1.5 N, and 15 ± 2 N. When juxtaposed with conventional teaching grinding methods, our approach manifested a reduction in grinding forces by 71.4%, 70%, and 75%, respectively. Post-grinding, the workpieces presented a pronounced enhancement in surface texture, exhibiting a marked increase in surface uniformity. Surface roughness metrics, originally recorded at 17.5 μm, 17.1 μm, and 18.7 μm, saw significant reductions to 1.5 μm, 1.6 μm, and 1.4 μm, respectively, indicating reductions by 76%, 73%, and 78%. Such outcomes not only meet the surface finishing standards for complex-shaped castings but also offer an efficacious strategy for robot-assisted flexible grinding.

Effects of the Impacting Velocity and Angle on the Grinding Force, Force Ratio and Deformation Behavior During High-shear and Low-pressure Grinding

Background: Background: The normal grinding force is generally larger than the tangential one during conventional grinding processes. Consequently, several machining issues arise, such as a low material removal rate, a high grinding temperature, and poor surface integrity. To overcome the constraints associated with conventional grinding methods, a novel “high-shear and low-pressure” flexible grinding wheel is utilized. A thorough investigation of the influence of machining parameters on the highshear and low-pressure grinding performance from a microscopic perspective is focused. Objective: The effect of the impacting angle and velocity on the grinding force, grinding force ratio, and fiber deformation displacement is explored at the microscopic level. Methods: An impact model was established using ABAQUS software to explore and analyze the interaction results of micro-convex peaks with the abrasive layer under different processing conditions. Results: It was found that the normal grinding force Fn increased with both impact angle and velocity. Similarly, the tangential grinding force Ft is enhanced with increasing velocity. However, its magnitude is reduced with impact angle. Conclusion: The grinding force ratio is primarily affected by the impact angle, which displays a declining trend. The maximum fabric deformation displacement reaches 72.4 nm at an angle of 60° and at a velocity of 9 m/s.

THEORETICAL RESEARCH OF PROCESS REGULARITIES OF GRINDING STRUCTURAL-HETEROGENEOUS ORGANIC MATERIALS

For the efficient functioning and successful development of the animal production sector, the key condition is correct feeding of animals. This feeding is only possible if enough feed is produced, nutrient losses during harvesting are reduced, and feed is correctly prepared for feeding. The introduction of concentrated feed helps to achieve a balance between energy, protein and amino acid content in the animal ration. Technologists compose and select components of feed rations based on the species, age group, morphological and biological characteristics of animals, as well as other factors. Despite the chosen technology and feeding strategy, concentrated feeds such as processed cereals based on wheat, barley, corn and other crops continue to be the main source of nutrients for animals. The quality of grinding concentrated feed is important for animal productivity. This treatment results in the formation of numerous particles with a larger surface area, which promotes faster digestion and better absorption. Grinding is one of the most high-energy processes used in animal feed technology. Since plant residues are structurally uneven, this makes it difficult to use conventional grinding methods efficiently, which reduces their energy efficiency and requires the use of several grinding stages with appropriate equipment. In order to ensure efficient processing of agricultural plant residues, it is important to create an appropriate technical infrastructure, given the significant energy costs associated with traditional processes of preparing biomass for granulation. To do this, it is necessary to conduct research aimed at solving the problem of energy-efficient grinding of structurally heterogeneous materials, in particular materials that contain a large amount of moisture. This is what determines the relevance of this research topic.

Energy-Efficient Advanced Ultrafine Grinding of Particles Using Stirred Mills—A Review

The present literature review explores the energy-efficient ultrafine grinding of particles using stirred mills. The review provides an overview of the different techniques for size reduction and the impact of energy requirements on the choice of stirred mills. It also discusses the factors, including the design, operating parameters, and feed material properties, influencing the grinding performance. The review concludes that stirred mills have significant potential for achieving the energy-efficient ultrafine grinding of particles. Stirred mills have unique designs and operations, which provide higher grinding efficiency, lower energy consumption, and reduced media consumption compared to traditional tumbling mills. The review highlights the advantages of stirred mills over conventional grinding methods and their potential to revolutionise industrial processes while lowering the environmental impacts.

A comparative analysis of grinding of AISI D2 tool steel under different environments

Difficult-to-cut material, i.e., AISI D2 tool steel, has been widely adopted in metalworking industries to manufacture dies for piercing, blanking, drawing and thread rolling due to its excellent wear resistance and non-deforming properties. This article attempts an experimental study to determine the effect of cryogenic coolant (liquid nitrogen) on the grindability of AISI D2 tool steel as work material and its results are compared with the conventional dry and wet grinding methods. The effects of the cryogenic coolant on force components (i.e., tangential force, Ft and normal force, Fn ), specific grinding energy (u), force ratio, surface roughness parameters (Ra and Rz ) and microstructure were observed. The comparison results indicate a significant reduction in grindability indices such as 64% and 44% in Ft , 54% and 34% in Fn , 46% and 30% in Ra and 40% and 34% in Rz , respectively under cryogenic grinding at higher downfeed as followed to dry and wet grinding. The grinding performance in Ft , Fn , u and Ra was also improved with an increased delivery pressure of the liquid nitrogen (LN2). From the results, it is concluded that cryogenic coolant offers an influential method to improve grinding performance and surface integrity of AISI D2 tool steel.

Quality improvement of soymilk as influenced by anaerobic grinding method and calcium addition

Soymilk is one of the plant-based milk products containing great nutritional content and has an unpleasant beany flavour and low calcium content. In this study, different grinding methods and calcium salts fortification were applied to improve the flavour, calcium content, and stability of soymilk upon calcium addition. According to the results, preparing soymilk using the anaerobic grinding method significantly reduced the lipid oxidation (0.4781 meq peroxide/kg) and increased the sulfhydryl group content (24.25 μmol/g), compared to preparing soymilk using the conventional grinding method (0.7668 meq peroxide/kg and 15.68 μmol/g). As the results of different grinding methods, oxygen-free soymilk (OFS) has a lower amount of volatile compounds (75.04 μg/mL) than regular soymilk (RS; 966.65 μg/mL). The addition of calcium salts increased the particle diameter and viscosity of soymilk, where the significant increase was shown in calcium-enriched soymilk prepared using conventional grinding. The addition of calcium lactate reduced soymilk pH while calcium carbonate addition showed the opposite results. Soymilks enriched with calcium lactate have equivalent calcium bioavailability (28.99 and 31.21%) with cow's milk (29.47%) and significantly higher than soymilks enriched with calcium carbonate (23.73 and 22.35%). Thus, this study suggests the preparation of soymilk using the anaerobic grinding method with the addition calcium lactate as the calcium source. This combination can produce calcium-enriched soymilk with high acceptability without altering the initial sensory properties.

On the tool wear behavior during ultrasonic vibration-assisted form grinding with alumina wheels

Ultrasonic vibration-assisted form grinding (UVAFG) with alumina wheels has become a potential technology to machine the areo-engine blade root. In this work, the characterizations of wear patterns of grinding wheel surface morphologies, such as clogging, grain micro-fracture and pull-out, were performed under conventional form grinding (CFG) and UVAFG methods, respectively. In addition, the comparative grinding performances, including grinding forces and force ratio, protrusion height distribution of worn grains, ground surface quality for both grinding methods, were discussed. The results indicate that the tool clogging and grain pull-out under UVAFG method can be effectively improved compared to CFG method. More excellent sharpness ability of alumina wheels under UVAFG can be obtained due to the grain micro-fracture by high frequency impacting between tool and workpiece. Furthermore, the alumina wheels under UVAFG possess lower grinding forces, larger protrusion height values of worn grains, and better ground surface quality in comparison of the other grinding method.

Influence of green extraction process of nano fibrillated cellulose using subcritical water/CO2 on its properties and development of its bio composite

AbstractThe study proposes a new green extraction method of producing nano fibrillated cellulose (NFC) from softwood pulp (SWP) by using subcritical water/CO2. Subcritical water/CO2 led to a controlled hydrolysis of SWP and the treated SWP was fibrillated by sonication to produce NFC. Effect of process parameters (time, temperature, and pressure) on the crystallinity and thermal properties of NFC was studied to optimize the process conditions for controlled hydrolysis. The influence of the extraction process on the properties of prepared NFC was studied. Nanocellulosic materials were characterized by using field emission scanning electron microscopy, transmission electron microscopy, Fourier‐transform infrared spectroscopy, wide‐angle X‐ray diffraction, and thermo gravimetric analysis. The NFC obtained at optimum process conditions (100 bar, 145°C, and 30 min) showed significantly high crystallinity (66%) and high yield (75–80%) compared to the NFC prepared by conventional mechanical grinding method. The present method of producing NFC uses water and pressurized CO2, and therefore, eliminate use of acids and chemicals. Plasticized poly vinyl alcohol (p‐PVA) based nano composite with NFC shows significant improvement in thermal stability (36%), tensile strength (77%) with reduced water vapor transmission rate as compared to virgin p‐PVA indicating their potential as nanofiller for making bio composites.

Surface concentration and microscale distribution of hydrogen and the associated embrittlement in a near α titanium alloy

The hydrogen embrittlement of near α Ti-2.5Al-2Zr-1Fe alloy is demonstrated by the decreasing of impact toughness when increasing the charged H content in the near surface layer. In order to get knowledge of the role of hydrogen and the possible embrittle mechanisms, a series of experiments are performed. First, the fracture mode was analyzed by scanning electron microscope and optical microscope. Then the deuterium charge and secondary ion mass spectroscope (SIMS) study was carried out to obtain the precise distribution of H in microstructure scale. The transmission electron microscope (TEM) study was performed to identify whether hydride formation occurs. Both Focused Ion Beam (FIB) lift out and conventional grinding methods were used to prepare the TEM sample. No hydride was observed in the sample prepared by FIB lift out method, while hydrides appeared in the sample prepared by conventional method. The results suggest that hydride formation relates with the TEM sample preparation process rather than the H charge process. The charged deuterium was found to concentrate in β phase at α grain boundaries by SIMS, which should be the cause of crack growth along β phase. Among the hydrogen embrittle mechanisms, the weakening of β phase was most probably caused by hydrogen enhanced decohesion.

A simple high-throughput protocol for the extraction and quantification of inorganic phosphate in rice leaves.

PremisePhosphorus (P) is an essential macronutrient that is often limited in agricultural systems. Determining inorganic phosphate (Pi) contents of plant tissues is crucial for evaluating plant P status. Here, we present a simple, high‐throughput colorimetric microplate technique to measure Pi contents in rice (Oryza sativa) leaf tissues, based on the molybdenum blue reaction.Methods and ResultsWe used a hole puncher to sample small equal areas of leaf tissue for Pi extraction. We removed the leaf grinding and weighing steps, which are time‐consuming and normally required to release Pi from the tissues and to measure the biomass for data normalization, respectively. We showed that the punching method yielded comparable results to the conventional grinding method for two rice cultivars grown under various levels of P supply.ConclusionsCompared with existing techniques, this protocol is more suited to an initial screening, enabling one researcher to determine the Pi contents of thousands of rice leaf samples within a few hours.

A novel high-shear and low-pressure grinding method using specially developed abrasive tools

In this work, a novel grinding method using a special abrasive tool was first proposed to achieve high tangential grinding force and low normal grinding force. The abrasive tool was developed with flexible composites to remove workpiece materials under “high-shear and low-pressure” grinding mode. The concept of the high-shear and low-pressure grinding method was introduced in detail. Grinding tests were carried out on a precision grinder with the developed abrasive tool for single crystal silicon specimens. The results showed that the grinding force ratio between tangential force and normal force for the proposed grinding method was ranged between 0.9 and 1.3, which was three times larger than that of the conventional grinding method. It was verified that the developed abrasive tool possessed the grinding characteristics of high tangential grinding force and low normal grinding force. After grinding of silicon specimens for 120 min, the value of surface roughness decreased from 429.20 to 32.91 nm under the selected grinding conditions. The surface quality of the silicon specimens was greatly improved after grinding.

Effect of superfine grinding on the physicochemical properties of bulbs of Fritillaria unibracteata Hsiao et K.C. Hsia powder.

This work aimed to determine the influence of superfine grinding on the physicochemical properties of bulbs of Fritillaria unibracteata Hsiao et K.C. Hsia (BFU) powder. For this purpose, fine powder (FP) and two superfine powders (SPs) were obtained via superfine and conventional grinding methods. The properties of different powders were studied and compared. Compared with FP, SPs exhibited higher values in terms of the angle of repose, swelling capacity, ethanol extraction yield, total alkaloid content, and imperialine content, while lower values in terms of particle size and bulk density. Especially, the total alkaloid content of SP‐I increased by 66.7%. Proper grinding is more conducive to reduce particle size and improve alkaloid content. FTIR analysis indicates that no new functional groups produced after superfine grinding. XRD analysis suggests that grinding treatment lead to decreases in the crystallinity. Therefore, superfine grinding displays immense potential in the BFU application.

Model and formulation in grinding mechanism having advanced secondary rotational axis

“Grinding Mechanism having Advanced Secondary Rotational Axis” is one of the newer plane surface grinding methods that has an uncommon abrasion mechanism. Unlike conventional methods, in Grinding Mechanism having Advanced Secondary Rotational Axis, there are two rotations of a wheel. The first rotation is the same as the conventional grinding methods, which is the circumferential rotation. The other rotation is the newly developed axial rotation, where the wheel rotates around itself perpendicular to its radial axis. In the grinding process, the grinding force, energy, power, and temperature are directly related to the material removal rate. In this article, the chip model in Grinding Mechanism having Advanced Secondary Rotational Axis was addressed and material removal rate was reformulated. The new chip ratio formula was adapted to the grinding force, energy, power, and temperature in the conventional plane surface grinding method. The chip formed in the conventional plane surface grinding method consists of two-dimensional xy plane. In Grinding Mechanism having Advanced Secondary Rotational Axis, on the other hand, the chips consist of three-dimensional xyz plane. The reason behind this is the second rotation obtained in Grinding Mechanism having Advanced Secondary Rotational Axis (axial rotational motion). The chip model was obtained from the combination of two rotations in Grinding Mechanism having Advanced Secondary Rotational Axis. As a result, the resulting chip model increased the material removal rate only slightly and this increase was negligible. Accordingly, an increase in grinding force, energy, power, and temperature was observed at negligible rates.

Methodology and implementation of a vision-oriented open CNC system for profile grinding

CNC systems with the vision function have become very valuable for intelligence machine tools because machine vision is a fast-growing intelligent feature for machines. A novel vision-oriented open CNC system was developed in this study and used in profile grinding machines for the precise machining of parts with contour surfaces, such as complex molds and cutting tools. The system is an innovation to the conventional profile grinding method and enabled the profile error to be visually detected and compensated during the machining process. In this study, a novel design methodology for a machine-vision-oriented CNC system was proposed. An Ethernet-based hardware architecture was constructed for the vision-oriented CNC system. The software characteristics of the developed CNC system were analyzed, including a new type of multi-thread software architecture, a seamless handover approach for multi-thread accessing of the memory space, the integration of the human-machine interface with image processing, and virtual-axis-based online error compensation. The running efficiency test of the software development platforms, time-consumption analysis of the measurement and control in the vision-oriented CNC system, and verification of the effectiveness of the developed vision-oriented CNC system were performed. The results indicate that the proposed vision-oriented open CNC system can effectively fuse image processing with motion control, meet the efficiency requirement, and improve the machining precision of profile grinding. The results are also valuable for developing other machine-vision-based intelligent machine tools.

Improvement of grinding performance and investigation of cutting parameters using a grinding mechanism with secondary rotational axis

“Grinding Mechanism having Advanced Secondary Rotational Axis” (GMASRA) is one of the newer plane surface grinding methods that have an uncommon abrasion mechanism. Unlike conventional methods, in GMASRA, there are two rotations of a wheel. The first rotation is the same as in conventional grinding methods, which is the circumferential rotation. The other rotation is the newly developed axial rotation, where the wheel rotates around itself perpendicular to its radial axis. In this study, the effects of certain cutting parameters on arithmetical mean deviation of the assessed profile (the Ra parameter) were investigated. Particularly, the effects of cutting parameters on Ra in the GMASRA grinding process were examined. The selected cutting parameters were the depth of cut, the number of axial revolutions of the wheel, and the stepover distance of the wheel. Five wheels with different properties were chosen. Additionally, GMASRA was modeled using the Taguchi orthogonal test design. In this orthogonal design, the depth of cut, the spindle speed, and the type of grinding wheel were chosen as the control factors. The effect of the specified control factors on the surface roughness was demonstrated using an analysis of variance (ANOVA) test. Results show that GMASRA produced better Ra values than the conventional method. Ra values were very close to each other in every part of the ground workpieces. According to the modeling results, the spindle speed had the highest effect on Ra, followed by the depth of cut and the type of grinding wheel. GMASRA is also very cost effective and can be adapted to most milling machines and CNC milling machines.

Force prediction model considering material removal mechanism for axial ultrasonic vibration-assisted peripheral grinding of Zerodur

Axial ultrasonic vibration-assisted peripheral grinding (AUPG) has the major advantages of simultaneously improving the grinding quality and material removal rate compared with conventional grinding methods. In this study, a grinding force prediction model for the AUPG of Zerodur was developed to investigate the generation mechanism of the grinding force for guidance in practical engineering applications. Taking into consideration the material removal mechanism, material properties and vibration impact, the three primary grinding force components were first separately modelled, namely, the ductile removal force in the ductile removal phase, the brittle removal force in the brittle removal phase and the frictional force of the friction process. The critical uncut chip thickness and maximum uncut chip thickness were subsequently researched to define the two material removal modes in the AUPG of Zerodur, namely, the ductile removal mode and the mixture of brittle and ductile removal mode. The grinding force models of these two material removal modes were developed using effective grinding force component models. The instantaneous variation of the grinding force with time and space was also analysed to derive models of the final time-averaged normal force, tangential force and axial force. Finally, grinding experiments were performed, the results of which showed that the prediction errors of the developed model were only 7.37 and 11.53% for the normal and tangential grinding forces, respectively. The axial ultrasonic vibration was also determined to reduce the surface roughness by 18.0% compared with conventional grinding, while the normal and tangential forces were reduced by 27.31 and 22.52%, respectively. This indicates that AUPG affords a significantly improved grinding surface quality. The developed model enables an understanding of the comprehensive mechanism of AUPG and provides a basis for the development of the grinding force models of the other brittle materials.

Investigations of surface layer temperature and morphology of hard machinable materials used in aircraft industry during abrasive electrodischarge grinding process

AbstractIn this work the results related to the influence of selected electrical parameters of the abrasive electrodischarge grinding process on the surface layer temperature and morphology of machined samples in comparison to the conventional grinding method are presented. The basis of this work has been investigations of the deep grinding of surfaces of the samples made of titanium 5553 β, Inconel 617, Hastelloy X and magnesium AZ31 using a cubic boron nitride (CBN) grinding wheel with metallic binding agent. For the comparative evaluation of the conventional grinding and abrasive electrodischarge grinding, measurements of the specific grinding energy, temperature on the surface layer (at the contact of the grinding wheel‐workpiece) and geometric structure of the surface layer have been used.

Benchmark Comparison of High Voltage Discharge Separation of Photovoltaic Modules by Electrohydraulic and Electrodynamic Fragmentation

Recent years have seen an increasing interest in exploring alternative techniques to conventional grinding methods such as fragmentation by high voltage discharges. Although pulsed power has already been applied to break down complex composite materials, there is currently no systematic comparison between different types of discharge regimes such as electrohydraulic and electrodynamic fragmentation. The aim of this work is to present such a comparison based on the electrohydraulic and electrodynamic fragmentation of copper indium diselenide (CIS) photovoltaic modules for potential indium recovery. High voltage discharges are performed in a process vessel filled with demineralized water at ambient conditions. After fragmentation, individual fractions are weighed, milled and the indium content is determined by X-ray fluorescence (XRF). Both the electrohydraulic and the electrodynamic approach are suitable to efficiently separate thin-film photovoltaic composite material into its constituent layers. The separation result is not dependent on the voltage level, but only on the total pulse energy applied. Since the generation of discharges with higher voltages requires a higher investment into plant properties such as insulation and generator, a comminution at lower voltages, i.e., electrohydraulic fragmentation, is preferable to electrodynamic fragmentation at higher voltages. To reveal the specific strengths of the two processes compared here, further comparative work with different composite materials is required.