Influence Of Grinding Conditions Research Articles

Effect of the grinding process on the surface quality of ultrafine cemented carbide with different Co content

By using a resin bonded diamond grinding wheel, the influence of grinding conditions on processing quality of the ultrafine cemented carbides with different Co content were investigated. Through grinding experiments, the effects of grinding wheel linear speed, feed speed and grinding depth on the surface morphology, roughness, and residual stress of cemented carbides were studied, and the relationship between grinding conditions and machining quality was established. Then, the evaluation and prediction of surface quality according to the grinding parameters can be realized by using ternary regression analysis. Finally, gray relational analysis was applied to optimize the multi-objective concerning surface quality to find the optimal grinding process parameters. The grinding test results show that with the increase of grinding linear speed as well as the decrease of feed speed and grinding depth, the maximum undeformed abrasive particle thickness decreases, which improves the surface plastic removal ratio and reduces the surface roughness. The multi-objective optimization of the grinding process can be achieved by using gray relational analysis, the resulting optimal process parameters achieve the lowest residual stress and surface roughness, which provides a theoretical basis for the prediction and control of the surface quality of cemented carbide in the grinding process.

Study on the Grinding Kinetics and Magnetic Separation of Low-Grade Vanadiferous Titanomagnetite Concentrate

In recent years, a low-grade vanadiferous titanomagnetite concentrate (LVTC) produced in the northwest area of Liaoning has attracted more and more attention. However, it is difficult to recover and utilize valuable minerals such as iron, titanium, and vanadium, due to their special physical and chemical properties and complex mineral composition. Grinding and magnetic separation are two important operational units for recovering valuable metal components from vanadiferous titanomagnetite. Therefore, the grinding kinetics of the LVTC in northwestern Liaoning were first studied by means of grinding kinetics equations in this paper. The results show that the grinding process of LVTC is consistent with the grinding kinetics equation, and the sieve residues of particles approached a constant value after grinding for 30 min, resulting from equilibrium between the fragmentation and agglomeration processes. In addition, equivalent particle size (EPS) and specific surface area (SSA) were linearly proportional to the double logarithm of grinding time, and the correlation coefficients for fitted data by the Rosin–Rammler–Bennet (RRB) model were slightly higher than those by the Swebrec model, and could reflect the dispersibility and uniformity of particle size distribution (PSD) quantitatively. Then, the grinding products were separated by magnetic separation, and the influence of grinding conditions on the grade and recovery ratio of Fe and TiO2 in the LVTC was analyzed. As a result, grinding time has a significant impact on the recovery ratio and grade of Fe and TiO2 during the magnetic separation process, and the LVTC grinding duration is not as prolonged as it might be, as the optimal grinding time is 20 min. Titanomagnetite, ilmenite, and titanite are still the predominant phases in all magnetic separation products at optimal grinding time, but the intensity or content of these three minerals varies between magnetic separation products, and 232 kA/m magnetic field intensity has a higher separation efficiency than 134 kA/m magnetic field intensity.

An analytical force and energy model for ductile-brittle transition in ultra-precision grinding of brittle materials

The critical grinding depth of ductile-brittle transition is an important processing parameter to guarantee brittle materials machining in ductile mode. Nevertheless, it is a difficult task to predict the critical grinding depth considering multiple grain interactions due to the random grain distribution on the wheel. In our paper, a novel grinding force and energy model is established to predict the critical grinding depth with considering the random interactions between multiple grains, and experimental validations are carried out on single crystal silicon. In this process, the grain-workpiece interactions are explored by the actual grain protrusion heights and random grain distribution. The surface generation mechanisms of the ductile-brittle transition are comprehensively investigated by applying the numerical and experimental methods. It shows that the plastic ploughing and brittle fracture are the dominant material removal modes when grinding brittle materials. Moreover, validation experiment results indicate that the proposed model could accurately predict the realistic critical grinding depth with an average deviation of less than 9.2%. Finally, based on the proposed model, the influence of grinding conditions on the critical grinding depth are investigated in detail. The critical grinding depth increases with increasing grinding speed, while decreases with increasing feed speed. Hence, this research not only provides a new method for predicting the critical grinding depth, but also enhances the understanding of the ductile-brittle transition mechanism in brittle materials machining.

Influence of grinding conditions on the pulp chemistry and flotation of oxidised pyrite

The influence of grinding conditions on the pulp chemistry of oxidised pyrite and its subsequent flotation behavior was studied in this paper. The oxidised pyrite particles were ground with forged steel or 30% chrome steel either in atmosphere or in a nitrogen-rich environment in a Magotteaux Mill®. The in-situ pulp chemistry (i.e., dissolved oxygen, Eh, pH) was measured during grinding. The amount of iron and sulfur oxidation species in the solid and aqueous phases of the grinding slurry was determined using the EDTA (ethylene diaminetetra acetic acid) extraction technique. The flotation recovery of the dry grinding products and the grinding discharge in the absence and presence of a collector was determined. The results show that the flotation recovery of the ground samples relies on both the surface chemistry of the pyrite particles and the pulp chemistry of the discharge, which varies greatly between different grinding conditions. Grinding with forged steel under atmospheric environment and grinding with 30% chrome steel in a nitrogen-rich environment created a suitable pulp chemistry or produced little iron oxidation species, which are found to be the optimal grinding conditions for pyrite flotation.

Grinding of maraging steel 1.2709 with SiC grinding wheels and effect of grinding conditions on the surface roughness and wear of the wheels

Grinding is one of the basic finishing operations which can be used for parts made from different materials where high quality and surface accuracy is required. One of these materials is maraging steel 1.2709, which is used for the test samples for tensile testing. In this case, it is very important to achieve good surface quality. Wear of a grinding wheel is best expressed as G-ratio which shows us if the grinding parameters are selected correctly. This article deals with the influence of grinding conditions and grinding wheels on surface roughness and wear of the grinding wheels when grinding tool steel VACO 180 on a 5-axis grinding machine. The experiment was designed to investigate the influence of changes in cutting speed, depth of cut and using two different grinding wheels for these two values. At the end of the article, the results from the experiment are summarized and compared.

The influence of grinding conditions on surface roughness parameters of 20MnCr5 steel vacuum-carburised by single-piece flow method

The purpose of the experimental tests described in the article was to determine the effect of selected abrasive machining conditions on the value of surface roughness of 20MnCr5 steel samples. The samples were subjected to vacuum carburising (LPC) using the ‘single-piece flow’ method and high-pressure gas quenching (HPGQ) in a 4D Quenching chamber to obtain an effective case depth (ECD) of 0.4 mm. Next, the samples were ground with a Norton Vortex corundum grinding wheel. Cooling and lubricating fluid was delivered to the grinding zone using the flooding method (WET) and with the minimum quantity lubrication method (MQL). The samples were ground in one pass of the grinding wheel using two grinding depths – ae = 0.01 mm and ae = 0.02 mm. For each grinding test, surface roughness measurements were made using a stationary laboratory profilometer T8000 from Hommel Werke. These measurements enabled the determination of the 2D and 3D roughness parameters. Analysis of the measurement results showed that for the adopted test conditions, the use of the MQL method resulted in a decrease in surface roughness compared to the surface ground using the WET method. This property applies to both tested grinding depths.

Influence of Grinding Conditions and Tilting the Spindle on the Spindle Load when a 5-Axis Grinder is Used

This article deals with the influence of grinding conditions and tilting the spindle on changes in the spindle load when grinding tool steel on a 5-axis tool grinding machine. The experiment was designed to investigate any changes in cutting speed, feed rate or tilting of the spindle. The size of the load is very important, because the load can influence the tool life, the life of the machine components, quality of the surfaces and dimensional accuracy of the components. A medical femoral knee replacement was selected as the semi-finished component for the experiment, as its surface is a good representative of a complex-shaped surface. This article is limited only to the grinding of maraging steel MS1 with a CBN grinding wheel. The second part of this article is focused on the experiment where the spindle load is evaluated and the results of the experiments are compared.

Machined brittle material surface in grinding: modeling, experimental validation, and image-processing-based surface analysis

The wide utilization of high-quality brittle material products has been closely related with mechanical grinding; however, the prediction of ground brittle material surfaces has been rarely studied before. To fill this gap, a prediction method of machined brittle material surfaces with substantial details including machined surface topography and morphology has been proposed in this study. The method has been established based on the determination of each grain-workpiece micro interaction (i.e., brittle and ductile interactions) and considered the random wheel topography and grinding kinematics. Validation experiments of typical brittle materials (including optical glass, zirconia ceramics, and glass ceramics) have proved the proposed method could, to a large extent, describe realistic brittle material grinding process and predict the machined surfaces in terms of (i) brittle and ductile region proportions, and (ii) roughness and waviness. To show the method advance, the influence of grinding conditions on ground brittle material surfaces at the grain scale has been studied. Some new insights, which could enhance existing understandings of the brittle material grinding process and guide industrial manufacture, have been gained. Besides, an image-processing-based method has also been proposed to automatically not only recognize but also measure the brittle and ductile regions on the ground brittle material surface. Moreover, the experiments proved the high measurement accuracy as well as high method applicability. Therefore, the detection method is also expected to be able to facilitate the development of smart and intelligent manufacture which requires the high-level automation.

Influence of grinding conditions on machining characteristics of PCD in high-speed constant-pressure grinding

Influence of grinding conditions on machining characteristics of PCD in high-speed constant-pressure grinding

Wpływ warunków obróbki na chropowatość powierzchni po szlifowaniu wgłębnym stopu niklu 201

Wpływ warunków obróbki na chropowatość powierzchni po szlifowaniu wgłębnym stopu niklu 201

Badania wpływu warunków obróbki na chropowatość powierzchni obrobionej podczas szlifowania wgłębnego stopu tytanu Ti-6Al-4V na szlifierce kłowej do wałków

Badania wpływu warunków obróbki na chropowatość powierzchni obrobionej podczas szlifowania wgłębnego stopu tytanu Ti-6Al-4V na szlifierce kłowej do wałków

Basic Study on High Efficiency Ultra-Precision Grinding of the Optical Glass Lens

The demand for large aperture lenses with high surface quality and form accuracy used for single-lens reflex cameras has been increasing. Generally, large aperture glass lenses are produced by ultra-precision grinding. Considering the increasing global competition, the grinding process has to be improved. However, highly efficient grinding causes worse surface quality, which leads to much polishing and ultimately results in lower form accuracy. Thus in this study, aiming at the realization of highly efficient and precise grinding of glass lenses, cross grinding of optical glass BK7 is carried out. As a first step of the study, the influence of grinding conditions on the surface quality is investigated experimentally.

Orthogonal Experimental Study on the Grinding-Hardened Layer’s Depth and its Uniformity of 45 Steel

Based on the orthogonal experiment of grinding-hardening machine, this paper studied the influence of depth of cut ap, table speed vw and grinding method gm on the grinding-hardened layer’s depth and its uniformity of 45 steel. The results show that, depth of cut ap is the significant factor affected the average value of grinding-hardened layer’s depth, but the influence of grinding conditions on the uniformity are very limited. In actual application, it should adopt ap=0.6mm, vw=0.4m/min and up-down grinding method to enhance the quality of grinding-hardened layer.

Influence of dry and wet grinding conditions on fineness and shape of particle size distribution of product in a ball mill

The influence of grinding conditions on the production of fine particles and the width of the particle size distribution produced during ball mill grinding was investigated. The grinding experiments were carried out varying the grinding ball diameter under dry and wet conditions. The relation between the weight passing size observed in an arbitrary cumulative undersize fraction and the grinding time was expressed by modifying Tanaka’s semi-theoretical equation for the grinding limit. The fineness of the product was evaluated by the median particle size in undersize distribution, and the shape of the particle size distributions by three different size ratios calculated using 10%, 20%, 50%, 80% and 90% cumulative weight passing sizes, that showed the width of the particle size distribution. The median particle sizes of product obtained for the grinding limit in wet and dry conditions were around 0.5–0.6 μm and 2 μm, respectively. The width of the particle size distribution in wet grinding decreased with decreasing median particle size of the ground product, and the size distribution in dry grinding became nearly constant. The particle size distribution width was lowered by using smaller grinding balls in wet condition and larger grinding balls in dry condition.

粉砕方式を変えた転動ミル粉砕によるＳｒフェライト微粒子の生成

The processes for obtaining fine Sr-ferrite particles have direct efects upon the crystallite size and distribution of sintered Sr-ferrite specimens. The influence of grinding conditions on the production of fine Sr-ferrite particles during ball mill grinding was investigated. The grinding experiments were carried out under dry and wet conditions, and dry condition with methanol as a grinding aid. Particle size distributions of the ground products were measured by the microscopic method, and could be expressed accurately as described by a modified Gaudin-Schuhmann equation. The fine grindability of Sr-ferrite particles was evaluated by the median particle size in undersize distribution, and the ratio of 10% and 90% cumulative weight passing sizes that showed the broadness of the size distribution. Sr-ferrite particles with a median particle size of 0.8-1.0μm were produced. The broadness of the size distribution increased with decreasing median particle size of the ground products. The broadness of the size distribution by wet grinding and dry grinding with a grinding aid was lowered using larger grinding media.

Influence of Grinding Conditions on Residual Stress Profiles after Induction Surface Hardening

Induction surface hardening creates very desirable residual stresses in the hardened surface layer. Residual stresses are always of a compressive nature and are usually present to the depth of the induction-hardened layer. By the appropriate selection of grinding wheel and grinding conditions and taking into account the physical and mechanical properties of the workpiece material very favourable compressive residual stresses in the hardened surface layer can be retained. How is it possible to assure a desirable surface and surface layer quality after induction hardening and fine grinding Finding an answer to this question requires a very good knowledge of the process of grinding on the micro-level as well as knowledge of mechanical and heat effects acting on the layer of the workpiece including the type and condition of the grinding wheel. An allinclusive consideration of the numerous influences of the kind and condition of the tool on the changes on the surface and in the surface layer of the workpiece in the given machining conditions is described by the term “surface integrity”.

A Study on the Distribution of Heat in Cool Air Grinding with Porous Metal Bonded Diamond Wheel(Superabrasive/new wheel grinding process)

Influence of cool air on the cooling ability in grinding process has been studied. By blowing cool air through the grinding zone, heat is taken out of the grinding zone and the surface temperature of workpiece also is reduced. This is confirmed by some theoretical and experimental research. However, in order to use cool air on the grinding more effectively, the more theoretical research is necessary. In this research, we try to make clearly the influence of grinding conditions on the heat removed. We also try to make clearly the influence of cool air parameters as temperature, pressure and flow rate on the distribution of heat in grinding as well as the heat removed by cool air in order to give a optimal grinding conditions in cool air grinding. In addition, the application ability of cool air in grinding is apart of this research.

The influence of grinding conditions on the mechanochemical synthesis of zinc stannate

The aim of this work is the investigation of experimental conditions for mechanochemical synthesis of spinel zinc stannate (Zn2SnO4). Application of this material include manufacturing of CO, H2, NO, NO2, i-C4H10 and C2H5OH gas sensors, production of transparent conducting electrodes, window coatings and anode for use in photoelectrochemistry. Starting powder mixtures of zinc oxide and tin oxide in the molar ratio, in accordance with the stoichiometrics of spinel zinc stannate, were mechanically activated by grinding in a planetary mill for various periods of time in the interval of 0 to 160 min. Changes of physico-chemical characteristics and microstructural parameters in the ZnO-SnO2 system after grinding were followed using surface area analysis and X-ray powder diffraction, while thermal behavior was examined by differential thermal analysis and sensitive dilatometer. The beginning of zinc stannate phase formation was noticed after 40 min of grinding, and prolonged grinding leads to the formation of spinel zinc stannate as the major phase with insignificant amount of unreacted zinc oxide and tin oxide. The formation of spinel was accelerated with the increase of sintering temperature, and monophased zinc stannate was obtained when powder mixture was grinded for 160 min followed by sintering at 1200°C.

The basic study about the effect of single point grinding on the bending strength of brittle material

Single point grinding was investigated by using a sliding indentation apparatus. Sharp indenter sliding against brittle solid produces a scratch with a median crack. The size of the crack depends on the applied indenter load and the sliding speed. The effect of the crack size and its orientation on bending strength of glass is investigated experimentally. It is shown that the tested glass has high bending strength when the indenter load is low, bending direction is parallel to the scratch, and sliding speed is low. The results of bending test are predictable by fracture mechanics analysis including residual stress effect. This study makes it possible to understand the influence of grinding conditions on the bending strength of ground ceramics.

Contamination of quartz by iron in energy-intensive grinding in air and liquids of various polarity

The influence of mill power and grinding environment on the contamination of quartz by iron during vibration grinding was studied. It was found that the Fe content of ground powders increased with an increase in specific grinding energy that was independent of the conditions of energy supply, that is whether it was supplied by varying the mill power or the grinding time. The specific contamination expressed as the ratio of Fe content to newly created surface area depended upon the physical properties of the grinding environment. The influence of grinding conditions on the state of the iron in the products of grinder wear was investigated by Mössbauer spectroscopy and by measuring the magnetic susceptibility of the ground powders. It was shown that the iron produced from grinder wear is present in tow main forms: as a magnetically ordered form identical with the basic material of the grinder and in a form of finely dispersed iron/iron compound showing superparamagnetic behaviour. Based on the results obtained, the formation of a silica-supported iron or iron oxide catalyst was presumed. By this assumption, the catalytic decomposition of water and methanol that takes place during quartz at grinding by iron containing grinders can be explained.