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This paper investigates the potential of utilizing lubricated liquid carbon dioxide (LCO2 + MQL) as an alternative to conventional flood cooling in grinding operations. This approach could facilitate a transition towards fossil-free production, which is a significant challenge in industry. The alternative cooling–lubrication method relies on pre-mixed LCO2 and oil and a single-channel minimum quantity lubrication (MQL) delivery method, which has already demonstrated potential in machining with geometrically defined cutting edges. However, this method has been less explored in grinding. This study primarily evaluates the grindability of AISI 4140 steel, examining surface roughness, residual stresses, microhardness, grinding forces, and specific energy for different cooling–lubrication methods. The results indicate that LCO2 + MQL is capable of attaining surface roughness and microhardness that is comparable to that of conventional flood cooling, especially in the case of less aggressive, finish grinding. Nevertheless, the presence of higher tensile residual stresses in rough grinding suggests that the cooling capability may be insufficient. While the primary objective was to evaluate the technological viability of LCO2 + MQL in terms of grindability, a supplementary cost-effectiveness analysis (CEA) was also conducted to assess the economic feasibility of LCO2 + MQL in comparison to conventional flood cooling. The CEA showed that the costs of both the cooling–lubrication methods are very similar. In conclusion, this study offers insights into the technological and economic viability of LCO2 + MQL as a sustainable cooling–lubrication method for industrial grinding processes.

Brazed carbide profile mill cutters are widely used in the machining of wood, wood materials, and plastic to form various functional and aesthetic surfaces. Tools of this kind are used in serial and mass production and they are built today using very costly 5-axis grinding machines supported by specialized CAM software that is very expensive too. The paper first developed the possible concept of 5-axis grinding of brazed profile mill cutters using universal diamond grinding wheel shapes. The developed concept of 5-axis grinding served as a basis for the developed approach for 3+2-axis grinding of the brazed form mill cutters which is the essence of this paper. Verification of this set approach of 3+2-axis grinding is performed on a developed functional prototype of a simple 3+2-axis grinder (Axes XYZ are CNC controlled, axes B and C are unpowered axes and have fixed positions during grinding). Based on the established 3+2 grinding strategy complete grinding of a complex profile has been performed on a developed functional prototype. Shape and measures of the cutting edge profile achieved by grinding are inspected on an optical measuring system and showed exceptional results. The established 3+2-axis method of grinding is an economically successful alternative to costly 5-axis grinding machines, as well as to specialized software, presented in the paper through experimental and practical application. [ABSTRACT FROM AUTHOR]

Several approaches have been proposed over the years that may be used to predict the performance of industrial rod mills. Unfortunately, studies that allow comparing the accuracy in their predictions are very scarce. The work compares four methods for predicting size reduction in an industrial rod mill. These were the Bond work index method (BW) and the Callcott–Lynch (CL) model, both originally proposed for rod mills, besides the Herbst–Fuerstenau (HF) and the Austin–Klimpel–Luckie (AKL) models, first proposed for ball mills, but here adapted and applied to rod milling. A total of 10 industrial surveys were conducted of the industrial mill in dry grinding of coke breeze, covering operation under a variety of conditions, all of which at lower fillings than commonly used in industry (<15%). Since most conditions surveyed were not within the typical operating range for rod mills, simulations using the Discrete Element Method were used to predict the mill power, used as input in both BW and HF models. At first, the fidelity of methods that allow predicting full-scale mill performance solely from bench-scale information, namely BW, HF, and AKL, is compared. Results showed that they all presented high biases in their estimates of product fineness, with AKL predicting finer products whereas BW and HF predicting coarser products. Using then data from a single industrial survey for model calibration (base case), in addition to the bench-scale test results, a comparison of the four approaches became possible. Taking the absolute deviations between measured and predicted P80 values, it became evident that the HF provided the highest fidelity in the predictions, with mean deviations of 12.8%, AKL with 15.3%, with both BW and CL presenting deviations above 18%. The work thus shows that size-mass balance models that rely on fitting most model parameters from bench-scale tests (HF and AKL) can provide predictions with good confidence when data from an industrial base case are additionally used in fine-tuning the model, even when applied to describing rod milling under unusually low fillings. [ABSTRACT FROM AUTHOR]

The paper describes selected aspects of the optimization of grinding processes, taking into account the characteristic probabilistic features of this process. Characteristic features of the grinding process that influence the significant dispersion of the quantities used in the optimization process to define goals and limitations are indicated. Attention was paid to the reasons for uncertainty in the use of research results, imperfections in information extraction procedures and the limited amount of data in the use of simulation and regression models in optimization procedures. The issue of determining the durability of abrasive tools in grinding process optimization procedures was analyzed. Methodologies for defining tool life are specified, taking into account the dispersion of the values of controlled process parameters. The effects of interference were taken into account in the relationships describing grinding efficiency and costs. The benefits of optimization taking into account the probabilistic nature of the process were determined. [ABSTRACT FROM AUTHOR]

Novel pyridine derivatives were successfully synthesized by grinding, microwave-assisted, and conventional techniques. Ethyl 6-amino-5-cyano-2-methyl-4-[(1S,2R,3R,4R)-1,2,3,4,5-pentahydroxypentyl]nicotinate (1) was synthesized and used as a versatile reagent for the synthesis of novel compounds such as nicotinic acid, nicotinohydrazide, 3,5-dioxopyrazolidine, 1,2,4-triazole, cyanoacetamide, urea, 2,5-dioxopyrrolidine, 3-dioxoisoindoline, sulfonamide, Schiff base, and formamide derivatives by its reactions with a series of nucleophilic and electrophilic reagents. The results of the synthesis with the use of the grinding, microwave, and conventional techniques were compared. The structures and compositions of the newly synthesized compounds were confirmed by IR and 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. Some of the synthesized compounds were screened in vitro for the activity against two cancer cell lines. Ethyl 5-cyano-2-methyl-4-[(1S,2R,3R,4R)-1,2,3,4,5-pentahydroxypentyl]-6-(3-phenylureido)nicotinate showed a high cytotoxic activity and selectivity against cancer cells (HePG2: IC50 = 34.31 μM; Caco-2: IC50 = 24.79 μM). Imaging cancer cell lines treated by some synthesized compounds was performed by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Pear pomace, a byproduct of juice production, represents a valuable reservoir of bioactive compounds with potential health benefits for humans. This study aimed to evaluate the influence of drying method and temperature on pear pomace, specifically focusing on the drying kinetics, grinding characteristics, color, phenolic profile (LC-MS/MS), and antioxidant activities of the powder. Drying using the contact method at 40 °C with microwave assistance demonstrated the shortest duration, whereas freeze-drying was briefer compared to contact-drying without microwave assistance. Freeze-drying resulted in brighter and more easily comminuted pomace. Lyophilized samples also exhibited higher total phenolic compound levels compared to contact-dried ones, correlating with enhanced antioxidant activity. Twenty-one phenolic compounds were identified, with dominant acids being quinic, chlorogenic, and protocatechuic. Flavonoids, primarily isoquercitrin, and rutin, were also presented. Pear pomace dried via contact at 60 °C contained more quinic and protocatechuic acids, while freeze-dried pomace at the same temperature exhibited higher levels of chlorogenic acid, epicatechin, and catechin. The content of certain phenolic components, such as gallic acid and epicatechin, also varied depending on the applied drying temperature. [ABSTRACT FROM AUTHOR]

As high-alloy steel, 8Cr4Mo4V steel has been widely used in the field of high-speed aerospace bearings in recent years because of its excellent thermal strength, thermal fatigue, corrosion resistance, hardness, and thermal stability. In this article, the heat-treated high-strength tempered martensitic 8Cr4Mo4V steel is taken as the object of study with the investigation of advanced technology, such as X-ray diffractometer, scanning electron microscope, electron backscattered diffraction, etc. An in-depth and comprehensive discussion of the effects of different grinding parameters, such as depth, wheel linear velocity, cooling conditions, etc., on the microstructure of the surface metamorphic layer was carried out, and it was found that the surface metamorphic layer has an obvious microstructure gradient distribution. A new layering strategy for the metamorphic layers is proposed, from the surface to the interior in the following order: the large plastic deformation layer, the no acicular martensite layer, the mixed layer, and the matrix layer. Ultimately, the key to the formation of the large plastic deformation layer is the re-nucleation of surface austenite due to high temperatures, and the wheel assists the process of crystal orientation. Similarly, the mixed layer or the no acicular martensite layer appears as the tempered martensite reaches the phase transition temperature. The manufacturing parameters have a great influence on the gradient distribution of microstructure, and this study is intended to be a practical guide for the grinding of 8Cr4Mo4V steels. [ABSTRACT FROM AUTHOR]

On June 24, 2017, a catastrophic landslide destroyed the village of Xinmo (Maoxian County, Sichuan, China). A 2.87 × 106 m3 rock mass in source area collapsed and entrained the surface soil layer along the run-out path. This disaster took eighty-three people's lives and destroyed more than 103 houses. It is worth noting that rock fragmentation and grinding could expand the spreading area of danger zone in a landslide event. The Xinmo landslide provided a rare opportunity to infer the dynamic fragmentation and grinding of rock masses from the particle size and shape distribution in the entrainment and deposition area. A field investigation combined with an automatic image analysis system was conducted to study the characteristics of particle size and shape distribution along the debris channel. The image analysis of these field data showed that the median size (D50) of particles ranged from 0.41 to 27.71 m in the landslide area. Particle fractal dimension (D) obtained from the Number-size distribution ranged from 1.77 to 2.97 over the entire study area. Moreover, the evolution of D50 and D along the run-out path confirmed that the degree of cumulative rock fragmentation increased as the travel distance increased. Additionally, the particle roundness (R) ranged from 0.51 to 0.88 along the run-out path, which peaked twice during the motion of granular flow, once was in the entrainment area, and another was in the end of the deposition area. Rock scraping occurred in the entrainment area could increase the degree of rock grinding, and reshape coarse stones into smooth particles of large R values (larger roundness of particles could lead to longer spreading distance in a landslide event, due to the lower internal friction among particles). Based on analysis above, the rock scraping phenomena occurred between the source materials and entrainment materials were confirmed to influence the translation and spread of granular flows in landslides. [ABSTRACT FROM AUTHOR]

Extensive research in smart manufacturing and industrial grinding has targeted the enhancement of surface roughness for diverse materials including Inconel alloy. Recent studies have concentrated on the development of neural networks, as a subcategory of machine learning techniques, to predict non-linear roughness behavior in relation to various parameters. Nonetheless, this study introduces a novel set of parameters that have previously been unexplored, contributing to the advancement of surface roughness prediction for the grinding of Inconel 738 superalloy considering the effects of dressing and grinding parameters. Hence, the current study encompasses the utilization of a deep artificial neural network to forecast roughness. This implementation leverages an extensive dataset generated in a recent experimental study by the authors. The dataset comprises a multitude of process parameters across diverse conditions, including dressing techniques such as four-edge and single-edge diamond dresser, alongside cooling approaches like minimum quantity lubrication and conventional wet techniques. To evaluate a robust algorithm, a method is devised that involves different networks utilizing various activation functions and neuron sizes to distinguish and select the best architecture for this study. To gauge the accuracy of the methods, mean squared error and absolute accuracy metrics are applied, yielding predictions that fall within acceptable ranges for real-world industrial roughness standards. The model developed in this work has the potential to be integrated with the Industrial Internet of Things to further enhance automated machining. [ABSTRACT FROM AUTHOR]

Designing low‐cost, effective and greener materials via a non‐sophisticated strategy is most important for future research. Here, they made a new dual endeavor using carbon dots (CDs) as an environment protection probe for selective detection of environmental toxins, followed by the solid‐state structural reformer to prepare NiMoO4 (NM) via mechanochemical‐based solid grinding method. The prepared CDs, NM and NM‐CDs combination is examined through various techniques. The prepared CDs selectively detect Cr6+, Ru3+, and Doxycycline independently. Also, in this work, a groundbreaking strategy is found to prepare morphology‐tailored NM using CDs through a solid‐state grinding method without adding any other toxic solvents or reagents. The CDs‐induced NM‐CDs (15) look like a 2D nano‐sheet with enriched surface area compared to its bare NM. The fabricated electrode provides the highest capacitance value of 1947 F g−1, almost three times grander than the bare 1D rod‐like electrode. Then, fabricated asymmetric supercapacitor NM‐CDs (15)//AC system delivers a high energy density of 43.9 Wh Kg−1 at a power density of 684 W Kg−1. Overall, a single CDs serve multiple roles in the environment and energy applications with a greener structure tailoring agent and a better booster for re energy storage properties. [ABSTRACT FROM AUTHOR]

Current practices on rail machining show large variations in strategies and amount of grinding and milling. To identify reasons for this and suggest strategies to further optimise rail machining, objectives of machining are scrutinised and consequences of not fulfilling objectives are investigated. This leads to a discussion on potentially detrimental effects of rail machining and how to minimise these. With this background, general aspects of rail machining optimisation are discussed. The study shows several means to improve rail machining, but also how the potential is restricted by the current lack of knowledge and predictive models. This prevents quantifying benefits of innovative solutions, and complicates transfer of knowledge between different operational conditions and translations of (scaled and controlled) test results to (full-scale, uncontrolled) operational conditions. [ABSTRACT FROM AUTHOR]

As battery technologies evolve and the demand for sustainable energy solutions rises, the request for natural graphite is expected to remain strong. The graphite used in battery anodes is typically a form of high-grade purified flake graphite, which has a layered structure that allows for the intercalation of lithium ions during charging and discharging cycles. Since graphite is naturally hydrophobic, flotation beneficiation is the most utilized enrichment technique for upgrading. Different flotation conditions were investigated for graphite enrichment with various crystal particle sizes. Since the size of the flake directly affects its market price, providing an overview of ‘graphite flotation’ based on the flake size is essential for disseminating the process knowledge and promoting research advancements related to this critical mineral. Thus, as an innovative approach, this work assessed and reviewed published graphite flotation investigations based on flake graphite particle sizes and divided them into fine (<150 μm) and large (>150 μm) groups. The assessments emphasized that large flake graphite particles become irretrievable once their structure is damaged; thus, during their processing, it is essential to minimize the potential damage by separation from fine flakes. On the other hand, several issues are associated with the flotation of fine graphite, including high collector consumption and entrainment. Therefore, this overview focused on four main aspects of graphite flotation (flotation pretreatment, enhancement of the collection process, inhibition entrainment and presented examined solutions for optimizing grinding and flotation beneficiation) and addressed knowledge gaps within these areas. [ABSTRACT FROM AUTHOR]

The diamond grits pre-brazed using an amorphous nickel (Ni)-based alloy were accurately fixed onto some positions on a steel substrate by resistance spot welding with a hot-pressing function. The amorphous Ni-based alloy thoroughly wetted and wrapped the diamond grits in the pre-brazing process. After the resistance spot welding, the pre-brazed diamond grits and steel substrate formed a strong metallurgical bonding under resistance heat and electrode pressure. The diamond grits welded by resistance spot welding maintained sharpness similar to that of regular diamond grits. The maximum tensile stress of welded diamond grits pre-brazed using amorphous alloy reached up to 0.43 GPa. The stress state was attributed to the presence of carbides of moderate magnitude between the bonded cladding and diamond grits. Grinding tests showed that the grinding performance of welded diamond grits pre-brazed using amorphous Ni-based alloy was better than that of welded diamond grits pre-brazed using crystalline Ni-based alloy. [ABSTRACT FROM AUTHOR]

The study involves an analysis of diverse technologies for recycling complex chemical power sources, including processes such as unsealing, crushing, grinding, leaching with sedimentation, and filtration. The recycling technology for spent lithium-cobalt power sources, developed at the National Research Center "Kurchatov Institute," is explored. This technology involves discharging lithium-cobalt power sources in a NaCl solution, unsealing in a shredder under an inert atmosphere, grinding in a rotary cutting mill equipped with a cyclone, and further grinding in a disintegrator to produce mechanically activated powders. The article provides data on the elemental composition and product yield following discharge, leaching, and precipitation. In addition, studies were carried out on pelletizing the resulting powders by pressing and rolling in a rotary granulator with a flat die. To enhance efficiency, the characteristics of channels with variable cross-sections were examined, and a physical and mathematical model for constructing force diagrams within the die channels was developed. Force distribution diagrams along the length of the channel were obtained for four types of powders, enabling the prediction of the behavior of powders with different morphologies during their rolling on a rotary granulator with a flat die. [ABSTRACT FROM AUTHOR]

Linearity is an important factor that affects actuator accuracy. However, the high nonlinearity of KNN piezoelectric ceramics restricts their application in actuators. In this study, we used grinding stress to improve the linearity of ceramic chips, and used them to fabricate a laminated actuator. The ceramic sheets were ground to a thickness of 0.5 mm. During grinding, some areas of the ceramic changed from tetragonal to orthorhombic, owing to the grinding stress. The piezoelectric constant (d33) increased from 198 to 268 pC/N. Notably, the linearity of the ceramics improved. Seven pieces of ground ceramics were bound, to fabricate a laminated multilayer actuator with a total thickness of 3.5 mm. A DC voltage was applied to the actuator, and the displacement was measured. The displacement reached 0.73 μm under a low driving voltage of 200 V. A linear regression analysis of the displacement–voltage relationship was performed, obtaining the regression equation of the actuator. The linearity correlation coefficient was approximately 0.9903, implying that the actuator exhibits a high accuracy. The grinding stress improved the linearity, together with the piezoelectric properties of the ceramic chips, thus improving the actuator accuracy. This research will promote the application of KNN piezoelectric ceramics in actuators. [ABSTRACT FROM AUTHOR]

Using co-amorphous systems (CAMS) has shown promise in addressing the challenges associated with poorly water-soluble drugs. Quench-cooling is a commonly used CAMS preparation method, often followed by grinding or milling to achieve a fine powder that is suitable for subsequent characterization or further down-stream manufacturing. However, the impact of mechanical stress applied to CAMS has received little attention. In this study, the influence of mechanical stress on indomethacin—paracetamol CAMS was investigated. The investigation involved thermal analysis and solid-state characterization across various CAMS mixing ratios and levels of mechanical stress. The study revealed a negative effect of mechanical stress on stability, particularly on the excess components in CAMS. Higher levels of mechanical stress were observed to induce phase separation or recrystallization. Notably, samples at the optimal mixing ratio demonstrated greater resistance to the destabilization caused by mechanical stress. These results showed the significance of careful consideration of processing methods during formulation and the significance of optimizing mixing ratios in CAMS. [ABSTRACT FROM AUTHOR]

Zirconia ceramics are widely used in aerospace, precision machinery, electronics, and biomedical fields because of their high temperature resistance, wear resistance, strong electromagnetic response, and biocompatibility. Nevertheless, high brittleness and low shear strength seriously hinder the large-scale application of zirconia ceramics in industrial production. This paper mainly reviews the research advances on primary machining technologies of zirconia ceramics from two aspects. One aspect is traditional machining of zirconia ceramics, which primarily focuses on the issues such as tool wear, machined surface quality, and cutting force in milling and grinding of zirconia ceramics. And the other aspect is non-traditional machining of zirconia ceramics, which primarily focuses on material removal rate and machined surface quality of zirconia ceramics using the electrical discharge machining (EDM) by assisting electrode method. The machinability and machining quality of zirconia composite ceramics by EDM with the adding conductive phase method have also been analyzed. Furthermore, for the auxiliary machining methods, the effects of ultrasonic vibration-assisted machining (UVAM) and laser-assisted machining (LAM) of zirconia ceramics are comparatively analyzed and elaborated. Subsequently, the research progress of traditional and non-traditional machining of zirconia ceramics is summarized and discussed. Finally, different machining methods of zirconia ceramics were prospected, and their future development trends were discussed, which provides a reference for further improving the machining efficiency and accuracy of zirconia ceramics. [ABSTRACT FROM AUTHOR]

Proper choice of grinding parameters is important because productivity is limited by the possibility of grinding burns. Nondestructive testing (NDT), as Barkhausen noise (BN), can provide a tool for determining parameter limits. However, BN requires a threshold value for approval and requires multiple experiments to provide grinding parameters corresponding to high productivity. Other limiting process outputs, such as surface roughness, need to be fulfilled. In this study, process modeling, experiments and NDT are combined to produce optimized grinding parameters that fulfill the process output requirements and reduces the number of experiments for a new component. Design of experiments (DOE) grinding tests were performed with cutting power measurements. The outcome was verified with BN and surface roughness outputs. Then, using polynomial fitting, regression models were fitted into the BN, surface roughness and cutting power data. Malkin's temperature model was utilized to analyze the temperature rise in the grinding zone. Combining all models, a grinding productivity optimization problem was defined from a specific material removal rate perspective. The polynomial fits of BN results and cutting power showed good prediction capability, as expressed by their R2 values. The study provides a novel method to choose grinding parameters to produce quality parts with minimal loss of productivity. [ABSTRACT FROM AUTHOR]

A kinematic model of rotary dressing - cylindrical grinding for lead pattern prediction is presented. Analysis of dressing and grinding parameters, dressing forces, and wheel imbalance effects has been conducted, providing a comprehensive look at the interrelationships between them and the resulting lead pattern. For model validation, a series of experimental tests has been performed, where workpiece and simulation lead has been characterized according to MBN 31,007–7 standard. Results emphasize the significance of modelling and translate it into a useful tool for selecting optimal dressing and grinding parameters for achieving specific surface qualities where lead is minimised or eliminated. [ABSTRACT FROM AUTHOR]

This study investigates post-processing of additively manufactured (AM) low-alloy 42CrMo4 steel (AISI 4140) produced by powder bed fusion – laser beam (PBF-LB). While the PBF-LB process produces tempered martensite by in-situ heat-treatment, resulting in superior mechanical properties, finishing by grinding remains critical for use in precision components such as automotive gears. The grindability of the AM material is compared to conventionally produced steel and reveals comparable results to most of the grindability criteria tested. However, higher wheel wear is observed when grinding the AM material. This is likely due to the lack of machinability-enhancing inclusion treatment common in conventional steelmaking. [ABSTRACT FROM AUTHOR]

Previous studies have already demonstrated a clear influence of the different subsurface microstructures resulting from variations in case-hardening on machinability during gear grinding. However, the impact of the alloy system has not yet been considered in detail. In order to fill this knowledge gap, case-hardening layers are analysed using six case-hardening steels with different alloy systems and their resulting machinability during discontinuous profile grinding of gears is compared. In particular, the results indicate that the outer subsurface area (up to approx. 30 µm in depth) formed as a function of the alloy system has a significant influence. [ABSTRACT FROM AUTHOR]

An investigation is made into traverse diamond dressing of grinding wheels using radiused dressers. Previous methods have modeled dressing using an equivalent diamond-contact width. This method contains inherent problems, particularly with overlap ratio and dressing depth. In this study, the geometry is modeled as a series of scallops. Dressing sharpness is quantified using the concept of Aggressiveness, which unifies numerous disparate parameters into a single dimensionless parameter. Experiments show that this single parameter accurately quantifies dressing sharpness for radiused, rotary, traverse-disc dressing. Also, the concepts of minimum achievable specific energy and the transient nature of wheel sharpness are investigated. [ABSTRACT FROM AUTHOR]

This study introduces a new method for efficient and low-damage machining of Ti6Al4V: laser-assisted CBN belt grinding. The impact of laser power and grinding depth on the machining behavior of the material is investigated, the elemental distribution and chemical state of the ground surface are analyzed, and the removal mechanism of laser-assisted CBN belt grinding is described. The results show that increasing laser power will improve processing efficiency, enhance plastic material removal, and improve surface quality; the tangential grinding force is decreased by 63.5% and the normal grinding force is decreased by 72.6% at the maximum laser power; a large amount of Ti and N are present on the ground surface, and they are present in the form of TiN compounds. This study is a guide to the research on efficient and low-damage machining of hard-to-process materials like titanium alloys. [ABSTRACT FROM AUTHOR]

In order to reveal the material removal behavior of robot abrasive belt grinding (RABG) of nickel-based superalloy, the experimental research method of single grit grinding is proposed. In the research, ceramic alumina grits are used to scratch superalloy K438 based on the experimental setup of RABG. Four material removal parameters, namely real cutting depth, number of cutting edges involved in grinding, effective cutting area of cutting edges and pile-up ratio, are used to quantitatively describe the material removal behavior. The experimental results show that the grits have good cutting performance. And the cutting edges involved in grinding change dynamically, which has a significant influence on material removal. In addition, this paper analyzes the differences between RABG and wheel grinding (WG), studies the effect of cutting depth on material removal, and determines the factors that affect the material removal ability by evaluating the material removal ability of different grits. [ABSTRACT FROM AUTHOR]

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Determining grinding conditions to achieve part quality and production rate requirements is a challenging task. Due to the complexity of the process and many affecting factors, grinding conditions are chosen conservatively, mostly based on experience or handbooks to eliminate quality problems. Thus, an integrated modeling system is required to select grinding conditions in a systematic approach for high-performance grinding. The key feature required of such a system is the capability of producing results in a wide range of grinding conditions and parameters without the necessity of conducting extensive experimentation. This is feasible only by adopting geometrical-physical-based modeling for grinding which is a challenging task since most of the grinding process research is based on experimental methods involving calibration tests. In this study, by considering a grit representation of the grinding wheel and grit-workpiece interaction coupled with the material deformation model, a multi-dimensional modeling system capable of process predictions for a wide range of grinding parameters and conditions has been developed. Using this system, a digital twin-based framework is established to select grinding conditions in an efficient and proactive manner. Based on the simulation results of this new integrated system, some general guidelines are recommended with a systematic approach. This approach is demonstrated in a case study considering the process constraints showing how the material removal rate (MRR) can be maximized without sacrificing the surface integrity which is the main concern in this process. The proposed methodology offers a new outlook on grinding parameter selection, to be used in an integrated digital twin to increase part quality and productivity while respecting the constraints. [ABSTRACT FROM AUTHOR]

Copyright of Naturaleza y Sociedad. Desafíos Medioambientales is the property of Universidad de los Andes and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In today's modern manufacturing era, it is critical to have an environmentally friendly machining system. This research introduced a novel approach with a developed setup for applying liquid nitrogen (LN2) cryogen in cryogenic machining as an environmental concern. In order to facilitate meaningful comparisons, grinding experiments were carried out in three distinct environments: dry, wet, and cryogenic cooling. The experimental results revealed that compared to dry and wet cooling, cryogenic cooling is beneficial in lowering the grinding force (54-64% and 38-45% in Ft, 44-55% and 31-35% in Fn), reducing the temperature (64-69% and 50-56%), improving the surface finish, causing less damage to the surface condition, and forming C-type or semicircular chips. Also, the influences of different process parameters, which include table feed rate and cryogen pressure, on surface characteristics of AISI D2 tool steel while employing surface functional indices, namely, surface bearing index (Sbi) and core fluid retention index (Sci), were investigated. Outcomes showed that the Sbi and Sci values in cryogenic grinding were greater than those of dry and wet grinding under the same conditions. It was clearly observed that the results of Sbi and Sci under cryogenic cooling indicated better surface characteristics over the bearing characteristics and fluid retention properties of the ground sample. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the electric pulse disintegration of a natural mineral. The object of the study is the natural mineral quartzite of the Aktas deposit of the Republic of Kazakhstan. For the destruction and grinding of quartzite, a working cell of an electric pulse unit was developed. Electric pulse crushing is a modern technique for grinding a variety of materials, which provides the desired degree of grinding with a certain granulometric composition of the product and has a high ability of selective crushing. With the help of this technology, quartzite grinding was carried out with an increase in the capacity of capacitor banks from 0.25 mF to 1 mF, the pulse discharge voltage changed from 20 kV to 30 kV, the number of pulse discharges from 500 to 1,000, the inner diameter of the working cell from 60 mm to 80 mm. The results of the disintegration of a natural mineral by the electric pulse method allowed us to determine the degree of grinding of the finished product. The obtained results can be used in the study and optimization of the extraction of natural minerals, which is important for ensuring the sustainable use of natural resources and balanced economic development. Crushed quartzite is used in various industries, including the production of optical fibers, electronics and photovoltaic devices. A material with a particle diameter of 0.1 to 0.4 millimeters is used to create glass, ceramic and porcelain products, as well as insulation materials. Due to its homogeneous composition containing up to 98 % silicon oxide (SiO2) and excellent absorbent properties, quartz sand is also used as a filter material for water purification. [ABSTRACT FROM AUTHOR]

Death, cancer, and degenerative diseases are some consequences of the extensive use of conventional cutting fluid manufacturing worldwide. Even if these devastating consequences for human health could be suppressed, hydrocarbons, alkaline agents, heavy metals, ethanolamine, formaldehyde, and N-nitrosodiethanolamine are some related elements to interfere in the ecosystem and generation of the greenhouse effect when disposed of incorrectly. Additionally, several other chemical elements are responsible for pollution and act as antifoams, anticorrosive, detergents, emulsifiers, surfactants, and biocides, the latter responsible for extinguishing the interaction of fungi and bacteria in cutting fluids and considered one of the main harmful agents to human health. Although there are numerous indications of the harmfulness of cutting fluids, two factors are essential for their use: reducing friction and avoiding adhesion or clogging between the tool-workpiece by using oil-based fluids; and the reduction of temperature, when necessary, the use of higher cutting speeds, in which cooling is a factor of greater relevance, using water-based fluids for this purpose, which, although not entirely mineral oil, not even for this can be characterized as less harmful to the biosphere. An adequate cutting fluid must arrive at the cutting interface and react quickly with the chip to form a solid with low shear strength. Therefore, cutting fluids are essential in manufacturing processes that generate a high amount of heat, such as grinding, and the use of harmful elements is characteristic of the process. To mitigate the environmental impacts caused by the conventional application, the MQL has been the most promising alternative due to the nature of its operation, not requiring fluids with a high density of chemical elements since its application is unique and atomized. However, even though MQL reduces the amount of cutting fluid in the process, in various conditions, it does not ensure the quality of the workpiece. Auxiliary techniques, such as the wheel cleaning jet, direct a jet of compressed air in the opposite direction to the cutting surface of the grinding wheel, helping to remove the clogging and making the application of MQL feasible. Therefore, this study analyzed the influence of different cutting fluid application techniques on the advanced ceramic grinding process (Al2O3) using four different wheel-cleaning jet angles combined with three different feed rates. To study the phenomena of this new technique, surface roughness, roundness error, diametral wheel wear, G-ratio, grinding power, grinding cost analyses, and CO2 pollution emission involving each application were evaluated. As a result, the application of cutting fluid by the MQL + WCJ 30° technique showed satisfactory and viable results compared to the conventional technique while presenting the lowest values of cost and pollutant emissions, extinguishing an environmental liability while contributing to the preservation of the entire ecosystem. [ABSTRACT FROM AUTHOR]

The problem of studying a scratch from a single abrasive grain is formulated, which involves finite element modeling of the interaction of the abrasive grain with the workpiece and an experimental study of obtaining and processing the grain traces on the real surface of the samples. A comprehensive investigation technique is proposed, including modeling the process of a single microcutting with an abrasive grain in the software system for analysis by the ANSYS Workbench finite element modeling method and an experimental study of the surface after microcutting with a grain. The applied research technique showed that, in general, the microreliefs of the traces created by a single abrasive grain, obtained during modeling and in the experiment, have a similar nature. At the same time, the numerical values of the geometric parameters have a scatter explained by a number of factors. [ABSTRACT FROM AUTHOR]

A problem is formulated to investigate the influence of various factors of a single grain cutting process on the formed microrelief of the grain trace on the workpiece surface, such as the grain shape and cutting depth. Based on finite element modeling in the ANSYS finite element analysis software system in the Workbench environment of the interaction of abrasive grain with the workpiece, studies were carried out and the values of the geometric parameters of the microrelief of grain trace on the workpiece surface were obtained: depth, width, and mark area in the cross section, as well as the width, height, and area of the left and right piles in cross section. In addition to the geometric characteristics, the coefficient of material pushed into heaps was determined. The research methodology used made it possible to obtain the geometric characteristics of the microrelief of the trace from the abrasive grain and to determine their dependence on the cutting process factors: the abrasive grain shape and the depth of its penetration into the workpiece. [ABSTRACT FROM AUTHOR]

Gear drives are widely used in various fields and applications due to their properties and capacity. Their versatility, durability, and ability to transmit high torques as well as precision and reliability make them extremely useful in many fields of technology. They are widely used in industrial and energy machinery, vehicle drive systems, aerospace, medical devices, and many other areas. Gears can be manufactured using many technologies. This work focuses mainly on machining with particular emphasis on high-performance new technologies. The process of mathematical modeling of the gear and the machined profile is strongly related to CNC machining technologies. A robust correlation of systems supporting the design and modeling of sliding gears needed for the manufacturing process is presented in the article. It is very important to properly assess gears with correct manufacturing in accordance with a specific standard. The article presents an analysis of available methods for controlling gears using coordinate measurement techniques. Gear machining methods were assessed in terms of the technologies used as well as their productivity and manufacturing tolerance. [ABSTRACT FROM AUTHOR]

Grinding is an important part of precision manufacturing, and grinding wheel wear is a crucial factor affecting the processing quality. It will be of great significance to monitor the grinding wheel wear status in real-time and provide timely warnings during processing. To realize the real-time and effective monitoring of grinding wheel wear, a new grinding wheel wear state monitoring method based on the principle of electrostatic induction is proposed. The principle of electrostatic induction in the machining process is analyzed, and two methods of grinding wheel wear surface monitoring and chip-abrasive grain monitoring are proposed. The time domain signal is processed by Fourier transform and noise reduction, and the influence of grinding wheel wear on the electrostatic signals of grinding wheel, abrasive grains, and chips is analyzed. The results of titanium alloy grinding show that with the increase in the wear degree of the grinding wheel, the electrostatic quantity of the grinding wheel increases by 5.6 times, and the number of electrostatic pulses of abrasive grains decreases by 74%. The degree of grinding wheel wear can be characterized by the electrostatic quantity of the grinding wheel and the number of electrostatic pulses of abrasive grains. In contrast, the number of electrostatic pulses of chips, the electrostatic pulse peaks of abrasive grains, and chips have no apparent relationship with grinding wheel wear. The electrostatic monitoring method can effectively monitor the grinding wheel wear state in real time and provide a new solution for the online monitoring of grinding wheel wear. [ABSTRACT FROM AUTHOR]

The reprocessing tailings of iron ore processing plants is important from economic (as a secondary source of iron) and environmental points of view. The aim of the present study is to determine the appropriate method for recovery iron from the tailings of Balestan iron ore processing plant (located in the northwest of Iran). For this purpose, after taking samples from the tail piles of this plant, a representative sample was selected, and chemical, mineralogical, size distribution, and bond’s work index analyses were performed on it. The total iron grade in the tailings was measured to be about 10%, of which 8.5% was identified as magnetite mineral (with a degree of liberation less than 40%). The d80 value of the sample was 7 mm, and the bond index was measured as 11.84 (kWh/ton). To determine the appropriate method for iron recovery, pre-processing with magnetic drum, grinding, and Davis tube tests were performed. With the magnetic pre-processing of tailings with a particle size of 0-10 mm, under a field of 2000 G and in a dry method, about 80% of the load entering the drum with a total iron grade of 5% was transferred to the tailings. 20% of the input load with an iron grade of approximately 24% was recovered to the concentrate. In order to remove the gangue minerals and enrich the pre-processed concentrate, stepwise grinding and separation had the best results. Comminution was done in two stages to produce products with smaller dimensions of 250 and 45 microns, respectively. Magnetic separation was also done in three stages with 3000 G, and two stages of separation with 1000 G, which finally resulted in a concentrate with a total iron grade of more than 66% and iron recovery of 44.88%. [ABSTRACT FROM AUTHOR]

The effect of induction heating on the surface properties of hot-pressed ceramics based on plasma chemical nanopowders Si3N4 and TiN (additives: Al2O3, AlN, and Y2O3) has been studied. The research demonstrates the formation of a modified layer on the surface of the hot-pressed material. The study examines the porosity, hardness, fracture toughness, brittleness, distribution of elements, and wear of hot-pressed ceramics on the surface before and after additional grinding. Removal of the surface porous layer results in increased density and hardness, leading to a higher number of acoustic emission signals during scratching with a Vickers indenter. A different response to scratching indicates a transgranular or intergranular fracture of the structure. The presence of porosity and carbon contamination on the surface layer of materials negatively impacts the properties of TiN-reinforced ceramics based on Si3N4-Al2O3-AlN (SIALON). However, the addition of Y2O3 effectively prevents carbon penetration and reduces the effect of grinding. Additionally, the dark-colored tone observed on the outer volume of the samples suggests a non-thermal microwave effect of the induction furnace. [ABSTRACT FROM AUTHOR]

The cement industry has committed to take drastic steps to reduce process‐related CO2 emissions to achieve climate neutrality by 2050. One essential part of the solution is the reduction of the average clinker content in cement. However, the limits of availability of common composite materials are already reached, and focus is laid meanwhile on calcined clays as the next generation SCM. The knowledge about the effects of calcined clay in cement and also the development of production technologies are well‐advanced. Now it is the task to earn acceptance on customer's side project by project. For that purpose, the presented paper sums up the state of the art of clay activation by answering the most urgent questions of clients. This also includes a review of LOESCHE's experiences with clay calcination and grinding gained in the recent years. LOESCHE combines its competence in this technology in the product C/CLAY® supplying individual solutions for all process steps from pretreatment over calcination to finish grinding. The most practical C/CLAY® methods, the flash‐calcination and rotary kiln firing, are explained with their complete process chains, whereby the latter provides a suitable option for retrofitting stopped cement production lines. As example, the layout of the world's biggest clay calcination plant designed by LOESCHE's subsidiary DYNAMIS is presented. [ABSTRACT FROM AUTHOR]

The grinding process via friction at the micro-scale in a mill with stones is considered a variable combination of contacts, with two-body (the asperities of lower millstone in direct contact with the asperities of upper millstone) and three-body (micro-particles of ground seeds trapped between the asperities of lower and upper stones of the mill) contacts. Three elements are described: (1) the mechanical contact of the asperities of the lower and upper millstones to predict pressures on asperities by modeling; (2) tests on a millstone sample covered with grinding particles; and (3) tests on a wafer sample formed by the millstones with the grinding particles between them. This paper highlights the combined effects of the micro-scale friction via individual measurements, using an analytical model to sum these effects and validating the model by performing several experiments. An efficiency grind by friction assumes the grain's movement and interaction between the seeds and solid surfaces, and is highlighted through theoretical and experimental studies. Topography analysis of the surface of the millstones reveals the model of microscopic frictional force. Endpoint measurements (the traces of the surface topography evolution) enable model verification in the grinding process. Thus, the results obtained in the grinding process in the stone mills via friction have practical utility through research benefits. Therefore, they allow for the improvement of quality, reliability, flexible grinding, quality control of the flours, and uniformity degree (fineness/shredding). [ABSTRACT FROM AUTHOR]

Purpose: Mercurial compounds are the classical Ayurvedic formulations extensively used in clinics. Kajjali or black sulphide of mercury, one of the primary mercurial compounds, is combined with herbs, metals, and minerals for internal use. Kajjali is prepared by mercury and sulphur, typically processed initially and then ground (Mardana) in equal proportions. The traditional method is manual, tedious, and time-consuming thus restricting mass production. Methods: The present study demonstrates a simple but innovative grinding method using a modified ball mill for preparing Kajjali in lesser time. Triplicate batches were prepared by both methods, and finished products were assessed using classical Ayurvedic as well as modern physicochemical parameters. Results: The improvised mechanical method reduced manufacturing duration by 3.6 times and increased production by 3.5 fold. A lustreless, very fine black powder obtained by both methods depicted meta-cinnabar with excess sulphur by X-ray diffraction while scanning electron microscopy revealed comparable morphology. Dynamic light scattering technique showed particle size ranged between 90 and 500 nm while thermogravimetric analysis recorded degradation at around 190 and 600 °C, indicating oxidation of sulphur and sublimation of HgS, respectively. Fourier transform-infrared spectroscopy detected the presence of organic matter, viz. fats in Kajjali due to the use of cow's ghee processed sulphur as raw material. Conclusion: The use of a modified ball mill was suitable for Kajjali preparation, enhanced productivity, and complied with good manufacturing practices. This innovative mechanical method yielded Kajjali of uniform particle size as compared to the manual method and can be enabled for automation. [ABSTRACT FROM AUTHOR]

Nanoparticle-enhanced coolants (NPECs) are increasingly used in minimum quantity lubrication (MQL) machining as a green lubricant to replace conventional cutting fluids to meet the urgent need for carbon emissions and achieve sustainable manufacturing. However, the thermophysical properties of NPEC during processing remain unclear, making it difficult to provide precise guidance and selection principles for industrial applications. Therefore, this paper reviews the action mechanism, processing properties, and future development directions of NPEC. First, the laws of influence of nano-enhanced phases and base fluids on the processing performance are revealed, and the dispersion stabilization mechanism of NPEC in the preparation process is elaborated. Then, the unique molecular structure and physical properties of NPECs are combined to elucidate their unique mechanisms of heat transfer, penetration, and antifriction effects. Furthermore, the effect of NPECs is investigated on the basis of their excellent lubricating and cooling properties by comprehensively and quantitatively evaluating the material removal characteristics during machining in turning, milling, and grinding applications. Results showed that turning of Ti–6Al–4V with multi-walled carbon nanotube NPECs with a volume fraction of 0.2% resulted in a 34% reduction in tool wear, an average decrease in cutting force of 28%, and a 7% decrease in surface roughness Ra, compared with the conventional flood process. Finally, research gaps and future directions for further applications of NPECs in the industry are presented. [ABSTRACT FROM AUTHOR]

In the grinding process, the metamorphic layer difference from the workpiece material is created on the grinding top surface, and its properties can greatly affect the bearing surface yield strength. In this study, the phase content and grain size distribution of 8Cr4Mo4V with the metamorphic layer were detected using advanced surface observation tools, and the influence of grinding process parameters on the microstructure of the metamorphic layer was considered at the same time. In addition, based on the modeling of the observed metamorphic layer with gradient microstructure distribution, tensile simulations of the metamorphic layer were performed by the crystal plasticity finite element method to investigate the effects of different grain size, phase content, and surface texture strength on its mechanical property like yield strength. Furthermore, the yield strength of the metamorphic layer was characterized by the nanoindentation technique. Finally, it was found that the grinding process parameters affected the microstructure and distribution of the metamorphic layer and thus changed its yield strength, and this study which combines the experiment and simulation aimed to quantitatively analyze the influence of different microstructures on the metamorphic layer.

Aiming at the problems of low processing efficiency, low groove shape accuracy and poor surface quality caused by grinding wheel wear in the grinding process of Cf/SiC composite grooves. In this paper, based on the motion mode of grinding wheel grinding, the wear volume formula of grinding wheels was analyzed, and the grinding wheel wear comparison experiment of different bond diamond grinding wheels grinding Cf/SiC composite grooves was carried out, and the more suitable kind of diamond grinding wheel for grinding Cf/SiC composite grooves was selected. From the experimental results, compared with the ceramic-bonded diamond wheel and resin-bonded diamond wheel, the grinding times of electroplated diamond wheel grinding Cf/SiC composites were increased by 20 and 104, respectively, and the surface roughness of the groove was most stable and the processing damage was smallest. Therefore, the best quality of grinding Cf/SiC composites groove was obtained by the electroplated diamond grinding wheel, and its life in grinding Cf/SiC composites was the longest. At the same time, the wear mechanism of the electroplated grinding wheel was explored, the wear on the bottom surface of the electroplated grinding wheel was more serious than that on the circumferential surface. The wear on the bottom surface was mainly wear and tear, and it gradually diffused along the inner diameter of the grinding wheel with the increasing grinding times.

One of the urgent problems of improving the quality of road surfaces is to improve the properties of bitumen used as binders. For this purpose, various modifiers are used, which are mainly obtained synthetically. Modification of bitumen with natural raw materials is favorable from an economic and environmental points of view. The modification of road oil bitumen with samples of shungite from the Koksu deposit (Kazakhstan) was carried out in the work. The shungite samples were previously crushed by mechanochemical activation to improve their surface and adhesive properties. As a result of modification with shungite, an increase in the softening temperature and a decrease in the extensibility and penetration of bitumen were observed. The optimal amount of added shungite turned out to be 1 mass %. The shungite of carbonate origin on a mineral basis is more favorable as a modifier compared to samples of shale origin.

In this research, the usage possibility of minimum quantity lubrication in grinding super alloy Inconel 738 has been studied empirically to reach improved grinding and lubricating conditions. For reaching this purpose, based on Taguchi design of experiment method grinding variables were set in three levels and lubrications were set in six levels in order to compare conventional, dry and MQL methods. Studies have shown that in grinding this material by MQL method we can obtain the results very close to conventional mode in terms of force and surface roughness even having better surface quality. Results in MQL method by considering various oils with different viscosities show that Behzist 6046 and Canola herbal-based oil are the best replacement of conventional method in terms of force reduction and surface roughness. In fact, in the case of using the MQL method together with Behzist 6046 oil, a 50% reduction in the force output is observed and when using Behzist 6043 oil, there is only a 30% difference in the surface roughness obtained with the traditional method, which creates a better surface smoothness is visible. For all the 100 investigated modes, the results show that the optimal levels for the variables of advance speed, stone wheel speed and chipping depth are level 1, 2046 rpm and 5 microns, respectively. The specific vertical force can be predicted in more than 50% of the tests with the least error (about 20%).

Abstract New derivatives of heterocyclic bearing pyrazole moiety were synthesized (eight new compounds from 2 to 9) via green synthesis methods (microwave-assisted and grinding techniques). 4,6-Diamino-1,3-diphenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (2) shows high anti-cancer activity against both HepG2 and HCT-116 with IC50 of 9.2 ± 2.8 and 7.7 ± 1.8 µM, respectively, which referenced to 5-Fu which is showing activity of 7.86 ± 0.5 and 5.35 ± 0.3 against both HepG2 and HCT-116, respectively. The cytotoxic activity against HCT-116 and HepG2 was slightly decreased and slightly increased, respectively, by a different pyrazole moiety (compound 5). Pharmacokinetics of compound 2 was carried out using the radioiodination technique in tumour-bearing Albino mice which shows good uptake at the tumour site. The biodistribution showed high accumulation in tumour tissues with a ratio of 13.7% ID/g organ after one hour in comparison with 2.97% ID/g organ at normal muscle at the same time point. As I-131 has maximum beta and gamma energies of 606.3 and 364.5 keV, respectively, therefore the newly synthesized compound 2 may be used for chemotherapy and TRT.

Abstract The service cycle and dynamic performance of structural parts are affected by the weld grinding accuracy and surface consistency. Because of reasons such as assembly errors and thermal deformation, the actual track of the robot does not coincide with the theoretical track when the weld is ground offline, resulting in poor workpiece surface quality. Considering these problems, in this study, a vision sensing-based online correction system for robotic weld grinding was developed. The system mainly included three subsystems: weld feature extraction, grinding, and robot real-time control. The grinding equipment was first set as a substation for the robot using the WorkVisual software. The input/output (I/O) ports for communication between the robot and the grinding equipment were configured via the I/O mapping function to enable the robot to control the grinding equipment (start, stop, and speed control). Subsequently, the Ethernet KRL software package was used to write the data interaction structure to realize real-time communication between the robot and the laser vision system. To correct the measurement error caused by the bending deformation of the workpiece, we established a surface profile model of the base material in the weld area using a polynomial fitting algorithm to compensate for the measurement data. The corrected extracted weld width and height errors were reduced by 2.01% and 9.3%, respectively. Online weld seam extraction and correction experiments verified the effectiveness of the system’s correction function, and the system could control the grinding trajectory error within 0.2 mm. The reliability of the system was verified through actual weld grinding experiments. The roughness, Ra, could reach 0.504 µm and the average residual height was within 0.21 mm. In this study, we developed a vision sensing-based online correction system for robotic weld grinding with a good correction effect and high robustness.