Use Of Grinding Research Articles

Influence of preparation parameters on the properties of SiC abrasive stones and their applications

AbstractThe preparation of highly efficient and low cost abrasive stones has gained considerable interest in the last few years from the industrial and academic research societies. Meanwhile, composition of such abrasive stones material has played a significant role on its physicochemical, mechanical properties and cost. In this work, series of magnesium oxychloride cement samples were prepared by adding MgCl2 solutions to magnesia, where H2O/MgCl2 was 13:1, 15:1, and 17:1, while MgO/ MgCl2 molar ratio was fixed at 7:1 for all samples. During mixing, two grades of SiC were added separately in proportions of 20, 25, and 30 mass percentage. A comprehensive characterization including bulk density, compressive strength, abrasion resistance, and polishing performance were carried out to the prepared composites samples. This was followed by studying their mineral composition and the possible use in grinding and polishing processes of marble slabs. Interestingly, the obtained characterization results demonstrated that among the different prepared composite materials, 25 mass percent SiC‐containing samples showed the best physicochemical and mechanical properties. Notably, the degree of fineness of SiC has affected the overall properties of SiC composite. When very fine SiC type was used and the water content was reduced, consequently, the samples bulk density and abrasion resistance increased. Phase 5 (5Mg(OH)2.MgCl2.8H2O) and silicon carbide, as the main phases with a minor amount of magnesia, were detected in the samples. From the economic point of view, the obtained result in our study is promising for its high performance‐low cost for grinding and polishing of marble slabs in the industrial fabrication.

Peningkatan Kapasitas Produksi Terasi Rebon di Desa Ketapang, Kotamadya Probolinggo

Kademangan is a shrimp paste production center in the Probolinggo municipality. The shrimp paste made from this fish processing center is of lower quality than similar products on the market. The varying size of the raw materials is a significant problem in shrimp paste production in this business hub. This activity aimed to improve the quality of the shrimp paste product by introducing and enhancing the partners' skills in using grinders and shrimp powder for rebon shrimp in making rebon shrimp paste. The method of this service activity consists of training, monitoring, and evaluation of the activities. This activity showed that the partners had received training on the production of shrimp paste and its quality and the use of grinding machines and machines for boiling shrimp meal. During the partner monitoring period, it became apparent that the partners had switched the technology from manual production of shrimp paste to machine production. The evaluation results show that the partners are familiar with grinding and grinding machines in making Rebon shrimp paste. The resulting products are of higher quality than those made before the partners used the shrimp grinding shrimp flour machines. The conclusion is that the use of grinding and flour machines for rebon shrimp by partners has increased the production capacity by three times and increased the quality of the rebon shrimp paste.

Effect of whole-grain rice on pellet quality, geese performance, and economic benefits

This study evaluated the effects of whole-grain rice ( WGR ) on pellet quality, geese performance, and economic benefits. A total of 360 one-day-old healthy male Jiangnan White goslings with similar body weight ( BW ) were randomly divided into 2 groups with 6 replicates per group and 30 geese per replicate. Pelleted diets were prepared with WGR for the experimental group and crushed rice ( CR ) for the control group to create the 2 treatments. Dietary rice (unhusked) inclusions were 20% for 1 to 21 d and 40% for 22 to 70 d. The pellets from d 1 to 21 were crumbled. Prepelleted WGR significantly decreased pellet length, hardness and pellet durability index. WGR pellets had significantly higher fine ratio (≤2.8 mm) and starch gelatinization than CR pellets. The different treatments did not affect BW on 21, 42, and 70 d of age or average daily feed intake ( ADFI ), average daily gain, and feed to gain ratio (F/G) from 1 to 70 d. However, compared with the CR diet, the WGR diet increased ADFI and F/G from 1 to 21 d. At 70 d of age, similar slaughter performance, relative viscera weight, and meat quality of geese were observed, except for a significant increase in the spleen ratio in the WGR treatment compared with the CR treatment. From the observation, pelleting with WGR reduced the cost of feed manufacture by decreasing the electricity use of grinding and had no negative effect on feed cost per/kg weight gain of geese. Even with the decreased pellet quality, we recommend replacing CR in geese diets with WGR from 22 to 70 d of age in view of the geese performance, economic benefits, and electricity savings.

Research on the Grinding Energy Density in a Jet Mill.

Raw materials are used in many industrial technologies. The raw material frequently has to be prepared as an intermediate with an appropriate particle size distribution, which requires the use of grinding. In grinding processes, energy consumption is a very important profitability criterion for the applied particular size reduction technology. The paper describes the comminution process that takes place in the jet mill using a modified form of the thermodynamic theory of grinding. In this theory, new material characteristics have been added: the surface and volumetric density of grinding energy. The thermodynamic theory is a combination of the classical Kick’s theory and the modified form of Rittinger’s theory. The tested physical magnitudes are a measure of the energy consumption of the grinding process. They describe the energy that must be provided in the grinding process to overcome interactions between particles related to the volume and surface of the material. Knowledge of these magnitudes is necessary to model thermomechanical phenomena in the solid state. The paper presents the results of research on comminution in a jet mill, on the basis of which the values of the tested material magnitudes were determined. It is graphically shown how the values of the tested magnitudes depend on the grain size of the ground samples.

Effects of grinding-wheel cleaning system in application of minimum quantity lubrication technique

Abstract One of the peculiarities associated with the grinding process is the large amount of heat generation. Therefore, the cooling−lubrication technique plays an important role and must be conducted efficient. Even though the conventional cooling−lubrication technique generally outperforms all other techniques, its use is harmful to both the environment and the health of the operator. Thus, techniques that minimize the use of cutting fluids are necessary. Among the various techniques available, minimum quantity of lubrication (MQL) has been widely employed in machining scenarios. However, its use in grinding is questioned because of the poor surface finish generated and thermal damage due to the clogging of the abrasive wheel pores during grinding. To overcome these problems, in this study, an auxiliary cleaning system (CS) of the wheel was used to remove the chips and oil from the clogged wheel surface during grinding, while assessing the CS performance with the aim of making the MQL a technically viable cooling−lubrication alternative. Grinding trials were performed on hardened steel under three different cutting conditions using the conventional (flood) cooling−lubricant technique and the MQL technique, by applying a biodegradable cutting fluid, with and without the CS. The CS performance was evaluated with regard to the roughness, roundness errors, wheel wear, grinding power, microhardness and residual stresses. Results of both surface roughness and grinding wheel wear were also used to determine empirical equations comparing the traditional MQL technique and the MQL technique with auxiliary cleaning system (MQL + CS). The results showed that MQL assisted with the CS can improve the machined surface integrity, reducing the surface roughness, roundness error and the variation in the microhardness. Furthermore, the MQL + CS condition also presented lower grinding wheel wear.

Grinding hardened steel using MQL associated with cleaning system and cBN wheel

The minimum quantity lubrication (MQL) is one of the most promising alternative techniques to replace the conventional application of cutting fluids. However, its use in grinding is still a challenge, as overheating and wheel clogging occur, leading to workpiece quality worsening. This work investigates a wheel cleaning jet associated with the MQL (MQL+WCJ) at three flow rates in grinding of AISI 4340 hardened steel with a cBN wheel, comparing the results with MQL and conventional methods. The output parameters assessed were workpiece surface roughness, roundness deviation, and microhardness, diametrical wheel wear, acoustic emission, and grinding power, and the machined surfaces were analyzed through microscopy techniques (optical, scanning electron, and confocal). The MQL+WCJ outperformed MQL in all the tested conditions. The application of the wheel cleaning jet reduced by up to 73% the wheel wear, 69% the surface roughness, 45% the roundness deviation, 60% the acoustic emission, and 24% the grinding power, regarding MQL without wheel cleaning, contributing to a more environmentally friendly and efficient grinding.

Development of an efficient technological scheme for processing graintriticale in bakery flour

The results of studies of the processing of initial samples of triticale grain in bakery flour according to the developed reduced and developed technological schemes are presented. When processing Ramses grains, the output of the T-70 grade of tritical flour (ash content no more than 0.70%) was 40% reduced by the technological scheme, and the yield of flour grade T-70 was 63% when processed according to the developed technological scheme. The total yield of flour according to the developed scheme, in comparison with the reduced one, increased by 3.4 and amounted to 75.5%. At the same time, the yield of the low-ash flour T-60 according to GOST 34142-2017 under the developed scheme was 46%, and according to the reduced scheme it was not possible to get a single percent of the tritical flour T-60.When processing grain grade "Saur" yield of tritical flour of grade T-70 and by the reduced scheme and by the developed scheme yield of flour amounted to 77.4%. When processed according to the developed scheme, the total yield of flour increased by 0.6 and amounted to 78.0% in comparison with the reduced scheme. At the same time, according to the developed processing scheme, 42% of tritical flour was obtained by ash content no more than 0.55%, and according to the reduced scheme it was not possible to obtain a single percent of tritical flour with an ash content of 0.55%.It is established that processing of triticale grain according to the developed technological scheme with the use of grinding and sieve systems allows to increase the total yield of flour by 0,6% -3,4% in comparison with the reduced technological scheme.

CONTROL ELEMENTS OF ENVIRONMENTAL SAFETY UNDER THE CONDITIONS OF CHEMICAL AND MAN-MADE FACTORS

The results of investigations are examined in terms of the development of custom ecological safety controls of the action of chemical and technogenic factors. The work is executed in the Department of Ecological Safety and Natural Management of Kremenchuk Mykhaylo Ostrohradskyi National University (Ukraine). The actuality of the theme is determined by insufficient knowledge of the simultaneous impact of factors of the formation of the ecological danger of different genesis, imperfection and the high cost of existing technical safety management tools. Research is conducted in the Kremenchug socio-economic area - region with the intensive technogenic loading. Where the simultaneous presence of constituents of the danger of different genesis and unfavorable keeping of its sources takes place in relation to the objects of the different setting. On results of monitoring of the states of the ecological danger, its regionally significant components and sources are identified: a waste disposal site, technological ponds of a washing and steaming station, technogenic earthquakes. On the basis of monitoring observations and instrumental measurements, manifestations of an ecological danger are recorded: exceeding the permissible concentrations of harmful substances in aquifers, as a result of which the water in the wells does not meet the standards and is not suitable for consumption; exceeding the permissible levels of vibrations of structural elements in living quarters, cracks and plastering of plaster were also found, temporary deterioration of people’s health was recorded. The system of technical decisions is developed on a management ecological safety. The technology of rendering of the ground deposits by destructors harmless is applied, due to what the sources of ecological danger are liquidated at the washing-steaming station. Experience of the improvement of position descriptions of sources of technogenic earthquakes is grounded, namely artificial change of parameters of environment with the purpose of limitation of area of distribution of waves to the dangerous objects (low-power explosions for the crushing of hard rocks, the construction of near-surface hollow protective structures filled with porous materials, the planting of certain tree species with developed root system). For cleaning of water objects from heavy metals, petroleum products, and fats, the sorbents of increased absorptive capacity, manufactured using an improved method (the use of grinding and mechanical activation processes) from wastes from the agro-industrial complex are used.

Interproximal grinding (disking) of caries in primary molars, attitudes and the extent utilized in a Swedish County

Objective: To assess the occurrence of interproximal grinding as a caries therapy in primary molars, to what degree grinding replaced conventional restorative caries therapy, to what extent anaesthesia was used while grinding and to assess open comments about attitudes about grinding.Materials and methods: A questionnaire was sent to 108 public dental service clinics with questions concerning the use of grinding as a therapy and alternative to restorative treatment, the use of anaesthesia prior to conventional caries therapy and grinding, respectively. In addition, a content analysis of open comments about grinding was performed.Results: Grinding had been performed in 96% of the clinics. Two-thirds of the dentists used grinding as an alternative to conventional restorative treatment at some point. Most dentists used anaesthesia prior to restorative therapy. Prior to grinding, the frequency of anaesthesia was lower (median 5.0) than for conventional restorative therapy (median 8.7) (p < .001). The open comment analysis revealed complex reasons for the use of grinding.Conclusions: Grinding has been widely practiced in parts of Sweden, is presently a technique employed by a multitude of dentists, and that anaesthesia is used less frequently prior to grinding, in comparison to conventional restorative therapy. Dentist considered grinding as a treatment option in specific situations.

A Case Study of Improved Watermill Using Power Electronics Devices for Offgrid Power Generation

The traditional water mills have low output with primarily use of grinding. The up gradation and improvement of these water mills is an effective and sustainable way of meeting the energy needs of a major section of the hilly people. This study discusses the case study of standard water mills developed in order to cover the entire range of water mills sites in Uttaranchal. Based on the site data available, 1 standard water mills have been designed, developed and tested for their performance. The developed water mills at Kherola village near Bhimtal, district Nainital have been found efficient. The status of water mills, energy situation in Uttarakhand, impact of water mill upgrade and the developed system have also been discussed.

Improving minimum quantity lubrication in CBN grinding using compressed air wheel cleaning

The application of minimum quantity lubrication (MQL) in grinding has emerged as an alternative for reducing the abundant flow of cutting fluids, thus achieving cleaner production. Although considered an innovative technique in grinding operations, its widespread application is hindered due primarily to the high heat generation and wheel pore clogging caused by machined chips, harming the final product quality and increasing tool wear on the machine. This study sought to improve MQL use in grinding. In addition to the conventional MQL injected at the wheel/workpiece interface, a compressed air jet was used to clean the mixture of MQL oil and machined chips from clogged wheel pores. Experiments were conducted using external cylindrical plunge grinding on AISI 4340 quenched and tempered steel, and a vitrified cubic boron nitrite (CBN) wheel. The cooling-lubrication methods employed were the conventional flood coolant application, MQL (without cleaning), and MQL with a cleaning jet directed at the wheel surface at different angles of incidence. The main goal of these experiments was to verify the viability of replacing the traditional abundant flow of cutting fluid with MQL and wheel cleaning. The analyses were conducted by measuring the following output variables of the process: workpiece surface roughness and roundness errors, diametrical wheel wear, acoustic emission generated by the process, and metallographic images of the ground surface and subsurface. Results show the positive effects of implementing the cleaning jet technique as a technological improvement of minimum quantity lubrication in grinding in order to reduce the usage of cutting fluids. The MQL technique with cleaning compressed air jet, for a specific angle of incidence (30°), proved to be extremely efficient in the improvement of the surface quality and accurate workpiece shape; it also reduced wheel wear when compared to the other cooling-lubrication methods that were tested (without a cleaning jet).

Ultrafine grinding of sugar cane bagasse ash for application as pozzolanic admixture in concrete

Sugar cane bagasse ash, a byproduct of sugar and alcohol production, is a potential pozzolanic material. However, its effective application in mortar and concrete requires first the controlled use of grinding and classification processes to allow it to achieve the fineness and homogeneity that are required to meet industry standards. The present paper investigates the role of mill type and grinding circuit configuration in grinding in laboratory- and pilot plant-scale on the particle size, specific surface area and pozzolanic activity of the produced ashes. It was observed that, although different size distributions were produced by the different mills and milling configurations, the pozzolanic activity of the ground ash was directly correlated to its fineness, characterized by its 80% passing size or Blaine specific surface area. From a low pozzolanic activity of less than 50% of the as-received ash, values above 100% could be reached after prolonged grinding times. Electric power requirements to reach the minimum pozzolanic activity were estimated to be in the order of 42 kWh/t in an industrial ball mill. Incorporation of an ultrafinely-ground ash in a high-performance concrete in partial replacement of Portland cement (10, 15 and 20% by mass) resulted in no measurable change in mechanical behavior, but improved rheology and resistance to penetration of chloride ions.

微粉砕, 分級, 粒子複合化を中心とした粒子設計加工による薬物の高機能化

微粉砕, 分級, 粒子複合化を中心とした粒子設計加工による薬物の高機能化

Effect of the synthesis conditions on the redox and catalytic properties in oxidation reactions of LaCo 1− xFe xO 3

The aim of this work was to study the effect of the synthesis conditions of LaCoO 3 on the redox properties and the catalytic activity for the CH 4 and CO oxidation reactions. Five LaCoO 3 samples were prepared by different methods: solid state (SS), coprecipitation (COP), citrate complexation (CIT) and reactive grinding of the single oxides (RG) and of an amorphous precursor (COPRG). TPD-O 2 experiments showed three kinds of oxygen. First, two surface oxygen species (designated as α-oxygens) were distinguished. The amounts of oxygen desorbing in the two α-oxygen desorption peaks were found to be mainly dependant on the specific surface area of the samples and stay lower than one monolayer (0.7–0.8). The last desorption peak, which is generally attributed to the desorption of some lattice oxygens (β-oxygens), was found to be more dependant on the morphology of the sample. H 2 reduction experiments (TPR-H 2) showed the usual two-step reduction. The reduction temperatures were found to be directly related to the calcination temperatures. H 2 uptakes and XRD analysis suggest a reduction of slightly more than one e − in the first step and the formation of some Co 0 before the beginning of the second reduction step. Kinetic analysis for the CH 4 oxidation reaction showed that the specific reaction rate is significantly affected by the synthesis procedure. Grinding an amorphous precursor results in a perovskite which combines a high specific surface area (made possible by the use of grinding) and a high activity. The RG sample presents a lower activity than COPRG, due to a higher iron contamination. Nevertheless, the differences observed in the oxidation reaction rate could not be correlated to the redox properties, measured by TPD-O 2 and TPR-H 2, of the catalysts. Then, these methods are not adequate to evaluate the reactivity of the solids. When tested in the CO oxidation reaction, the samples present different comportments than in the CH 4 oxidation reaction. These differences are discussed on the basis of the oxidation mechanisms involved in the two reactions.

Benefits of heavy rail on high-speed railways and design of 75G rail using coordinates

It has been common practice to use heavy rails on heavy haul railways to reduce rail defects and track deterioration. The clear advantages of using heavy rails on high-speed railways are discussed in the paper. Since future rails should guarantee the dynamic stability of rolling stock and be free of rail defects, it is appropriate to consider modifying the wheel running band formed by rail grinding. The author therefore proposes the use of a new 75 kg rail profile with full use of grinding (designated “75G rail”) which is developed based on experience in rail profile design in Japan. Mathematical equations have been applied to model the profile in place of drawing.

Use of grinding and liberation models to simulate tower mill circuit performance in a lead/zinc concentrator to increase flotation recovery

The paper presents findings from collaborative research on fine grinding, coordinated by the Australian Mineral Industries Research Association. The data reported here were collected from a tower mill circuit in the low grade mineral section of Mt. Isa Mines' Hilton Concentrator. Multi-component modelling, based on assays of size fractions, showed that the circuit was capable reducing the fresh feed from 110 to 15 μm at the desired throughout using about 22 kWh/t, provided classification at around 27 μm was installed. A benefit of about 3% recovery of both lead and zinc was indicated. A new simplified method of modelling grinding and liberation together is explained and verified by using parameters from the normal grind to predict, quite accurately, the size reduction and liberation achieved in a finer grind.

Design of rail head profiles with full use of grinding

To improve rail conditions on the Tokaido Shin-kansen line, studies on worn rail profiles and rail damage are first presented and the causes of damage assessed. Then the abrasion of rail corners on tangent track is taken up. Through the study of contact points between wheel and rail with the use of a coordinate transform, the fact that the lateral movement of bogies is accelerated by tilting of the rail is made clear. On the basis of these findings, new measures such as limiting the displacement of contact points between wheel and rail, cutting off neighbouring parts of the running fringe, having the rail head side conform to the tyre profile and cutting off the gauge corner on curves with larger radius and on tangent track are proposed, and a new rail profile with full use of grinding is designed.

Glue-Glove Technique for Use in Grinding and Polishing Thin Specimens

AbstractThis paper describes a new technique to assist in polishing plastic embedded specimens that are too thin to grind ade- quately when held with the fingers or mechanical devices. This technique, which we call the glue-glove technique, allows the successful grinding and polishing of thin specimens (1–2 mm thick) while minimizing specimen damage and eliminating finger injuries. (The J Histotechnol 13:63, 1990)

Diamond Grinding of Aspheric Surfaces on a CNC 4-Axis Machining Centre

The advantages of aspheric lenses over spherical lenses are well recognised. A properly manufactured aspheric lens is generally capable of a performance equivalent to three or more spherical elements. Hence the enhanced performance of the aspheric lens in cutting down the degree of spherical aberration and off-axis coma, gives it distinct advantages over the spherical lens in simplified mounting, lower light losses, lower weight, and compactness in design. However there is a major set back, that is – the cost. The present trend in the manufacture of precision aspheric surfaces is the use of grinding, lapping, and polishing. Though large scale research is on the direct moulding of precision aspheric surfaces, mouldings are at present restricted to lighting, condenser lens and other non-precision optics. Thus grinding still provides the answer to obtaining precision aspheric lenses. In the present study, the authors used a 3 axis CNC machining centre incorporating in it a 4th axis through the use of a rotary table which is made to oscillate on a horizontal axis. Mathematical programmes were developed to obtain concave parabolic surfaces. Aspheric surfaces were produced in less than 15% of the time currently required in optical industries thus heralding a major breakthrough for the precision optics industries.

Interstitial compounds

The field of interstitial compounds is a mature one, with an enormous literature. Nevertheless, a question as fundamental as the nature of their electronic structure remains a topic for lively (sometimes acrimonious) debate today. Moreover, industry has yet to tap more than a few of the myriad technical possibilities of these materials. The most commonly exploited property is their great hardness: tons of the interstitial compound tungsten carbide are produced annually for use in grinding and cutting tools. But other properties have seen little commercial application as yet. To cite a few: as a class, they are refractory, yet metallic, and they often have abnormally low work functions, making them excellent electron emitters. This combination suggests, for example, utility as magnetohydrodynamic channel electrodes. Some interstitial compounds, such as NbN, are superconducting, with transition temperatures second only to such champions as Nb3Sn. Tungsten carbide and related compounds are moderately good catalysts, able to operate in chemically hostile environments, as may be encountered, for example, in fuel cells. Many are respectable ferro- and antiferromagnets. As we will try to indicate, this class of compounds poses fascinating possibilities for the technologist and real challenges for the researcher.