Grinding Characteristics Research Articles

Grinding characteristics of Asian originated peanuts (Arachishypogaea L.) and specific energy consumption during ultra-high speed grinding for natural peanut butter production

Roasted peanuts of China and India origin were ground in a commercial ultra-high speed grinder operated at 20,000rpm for 2.0–5.0min for natural peanut butter production. Grinding characteristics of both peanuts were evaluated in terms of specific energy consumption, Esc with respect to its grinding time and mean particle size. The Esc increased with grinding time with China peanuts having higher Esc than India peanuts. The specific energy consumption modeled to the size reduction ratio of China and India peanuts was predicted more accurately using a linear and exponential model respectively compared to the classical models by Bond, Rittinger and Kick. From the comparison of Bond’s working index, Wi, the ultra-high speed grinder is said to be more energy efficient than other comminutors in terms of its capability to produce finer particle size in shorter time than the rest.

Experimental Research on the Characteristics of the Magnetic Compound Fluid by Grinding Solar Wafers

This paper studies the grinding characteristics of magnetic compound fluid by conducting large amounts of experiments. Magnetic compound fluid (MCF) is formed by mixing abrasive grains, α-cellulose, iron powder and Magnetic-Fluid together according to a certain proportion. The experiments are conducted to test the effect of process parameters (such as different period of time, various speed of main axle and fluctuating magnetic field) on grinding results using Solar wafers. The results showed that the grinding surface of solar wafers is within Ra0.1 after 3 minutes and the microscopic appearance of the surface is flat and free of burns phenomenon.

Effect of Thermal Shock on Grindability of Oleic Adsorbed Flotation Placer Sillimanite

Thermal shock is one of the most effective techniques in size reduction. The present investigation deals with the effect of thermal shock treatment on grindability and grinding characteristics of sillimanite minerals and also an attempt has been made on the overall energy saving for preparation of sillimanite flour by using ball mill. This attempt is made due to a fine dry grinding of sillimanite minerals to produce sillimanite flour, which is an energy intensive operation. It is observed from the present investigation that the particle sizes at d50 and d80 passing size in microns for thermally treated sillimanite is slightly lower than that of natural sillimanite. The study of grinding kinetics using ball mill indicate that the slope value obtained for thermally treated sillimanite is lower than the natural sillimanite, which shows that the sample responded to higher rate of grinding. The result of grindability studies reveal that the power required for thermal treatment of sillimanite is 395.36 hp and the total energy saving in the order of 8.9 % is achieved by thermal treatment of sillimanite at 900 °C for period of half an hour heating time due to development of numerous micro-cracks and fractures within the mineral grains. Hence, it is recommended to use thermally treated sillimanite for preparation of sillimanite flour (<75 µm particle size) which reduces power consumption of 8.9 %.

Detection and Analysis of Subsurface Cracks of Single Crystal SiC Wafers Based on Cross-Sectional Microscopy Method

For subsurface crack detection of single crystal SiC wafer, this paper proposed a cross-sectional cleavage detection method and compared with traditional cross-sectional sample preparation method. The characteristics and detection results of two cross-sectional sample preparation methods were compared and the subsurface crack characteristics in SiC wafer grinding were researched. The results show that the configurations and depth of subsurface cracks measured by two cross-sectional sample preparation methods were similar. The cross-sectional cleavage sample preparation method is simpler and more rapid in subsurface crack detection. The subsurface crack system of single crystal SiC wafer grinding mainly includes lateral crack and median crack.

Research on ELID Grinding Efficient Surface Forming Mechanism of SiCp/Al Composites

The electrolytic in-process dressing (ELID) grinding technology was adopted for precision grinding experiments of volume fraction of 40% of SiCp/Al composites, obtaining the machined surface roughness of Ra0.030μm. Studying the forming mechanism of processed surface, analyzing several typical grinding surface defects, summarizing the grinding characteristics and removal mechanism of SiCp/Al composites.

Machining Characteristics in Cryogenic Grinding of SiCp/Al Composites

In this study, liquid nitrogen was applied to grind SiCp/Al composites with high volume fraction and large SiC particle at different levels of cutting conditions, and the effects of grinding depth and speed on grinding force, surface morphology, and surface roughness were investigated. At the same time, the effect of cryogenic cooling was also compared with that of conventional wet grinding. The experimental results indicated that cryogenic cooling is effective in enhancing supporting function of Al matrix to the SiC particles and improving surface quality. Additionally, the brittle fracture of SiC particles was suppressed and some ductile streaks on SiC particle could be observed.

Influence of Cryogenic and Ambient Grinding on Grinding Characteristics of Fenugreek Powder: A Comparative Study

Grinding characteristics of fenugreek (cv. AM-1) were carried out at cryogenic and ambient conditions. It was observed that it affected average particle size, volume surface mean diameter, mass mean diameter, volume mean diameter, specific surface of mixture, number of particles per gram, energy constants – Rittinger and Kick's – and specific energy consumption. Values of average particle size, volume surface mean diameter, mass mean diameter, volume mean diameter, specific surface of mixture, number of particles per gram, Rittinger's constant, Kick's constant and specific energy consumption varied from 0.31 to 0.80, 0.31 to 0.57, 0.27 to 0.77, 0.25 to 0.41 mm; 16,413 to 34,254 mm2/g; 5,863 to 111,620 particles per gram, 4.97 to 35.87 kWh/t, 4.76 to 53.59 kWh/t, and 8.37 to 50.17 kWh/t, respectively, in the moisture content range of 5–15% wet basis at ambient and cryogenic grinding. Comparative study had shown that ambient grinding needs more power and specific energy than cryogenic grinding. Practical Applications The grinding characteristics of fenugreek powder will be useful to control the processing parameters and it will lead to improved quality and output of the fenugreek powder. The present study on grinding characteristics of fenugreek powder provides reliable information for design of equipments for handling, processing, packaging and transportation of ground powder, which will in turn be economically helpful for powder processing industries. The better color parameters of the fenugreek powder also cause enhancement of economy that may be seen with the help of present work.

Investigation on Properties of Magnesia Grinding Wheels Used in Silicon Wafer Grinding

This paper presents the results of an experimental investigation on molar ratios of MgO/ MgCl2 affecting the hardness of magnesia grinding wheels, which is one of the most important properties. Magnesite grinding blocks of different ratios of MgO/MgCl2 were prepared. The surface Rockwell hardness of which was tested under the same curing conditions. By an integrated assessment of the experimental studies of hardness and component, it is recognized that the molar ratios of MgO/MgCl2 can significantly affect the properties of magnesia grinding wheels. With the increase of MgO/MgCl2 molar ratio, hardness of the specimens increases. Scanning electron microscopy (SEM) studies on grinding blocks of different ratios indicated that micro needle shaped crystal structure of phase 5 are mainly responsible for hardness development. Finally the optimal recipe was selected in consideration of the characteristics of the silicon mechanical chemical grinding (MCG), which was verified to be effective by the following grinding experiment.

Investigation of Grinding Characteristics of Cemented Carbides YL10.2 and YF06

YL10.2 and YF06 are ultrafine-grained cemented carbides, and grinding experiments were carried out with resin-bonded diamond grinding wheel. Based on measured grinding force, surface roughness and SEM topography, experimental results were analyzed; grinding forces and depth of grinding approach linear correlation; and the grinding force of YF06 is greater than that of YL10.2 in rough grinding, but the grinding force increases significantly if depth of cut is greater than a certain value in finish grinding. The trend of machined surface roughness looks like “V” type with the increasing of depth of cut; the material removal behavior of ultrafine-grained cemented carbides in grinding was observed; the ploughing and fragmentation exist simultaneously on the ground surface, and the dominated material removal behavior depends on the grinding parameters or chemical composition of workpiece.

Surface Topography of Mini-Size Diamond Wheel in Ultrasonic Assisted Grinding (UAG)

The objectives of this paper are to describe a quantitative evaluation of mini-size diamond grinding wheel surface topography in Ultrasonic Assisted Grinding (UAG) process and demonstrate the effects of topography on grinding characteristics. In this study, threedimensional (3D) analysis of the wheel working surface was observed using a Scanning Electron Microscope (SEM) with four electron probes (hereafter described as 3D-SEM) in an on-surface UAG process. These results indicated that a good wheel surface maintained in the UAG process is related to the number and the area of cutting edges. Additionally, the resulting topographic features of the grinding wheel surface are closely related to low grinding forces and allow easy manufacturing of a mirror workpiece surface.

Behavior of the magnetic abrasive tool for cutting edge preparation of cemented carbide end mills

Magnetic abrasive processes combine characteristics of grinding and lapping. Due to deformable tool behavior, complex surface shapes and edges can be machined. Therefore, this process is predestined for preparation of drilled cutting tools. High quality finishing results require in depth process expertise. This paper focuses on the behavior of the magnetic abrasive tool taking Magnetfinish® kinematics into account. Main characteristics of the magnetic abrasive tool behavior during finishing end mills of 12 mm diameter are reshaping and in-process densification of magnetic abrasive layer. Consequently, flute surface modifications occur only in the cutting edge surrounding area. Furthermore, in-process displacements of magnetic abrasive cause non-uniform cutting edge rounding. SEM images indicate abrasive motion along the cutting edge as the best method to obtain smooth cutting edge surface.

Grinding Characteristics of Black Soybeans (Glycine max) at Varied Moisture Contents: Particle Size, Energy Consumption, and Grinding Kinetics

Abstract The effects of moisture content on the grinding characteristics of black soybeans were studied. The average particle size of the black soybean powder was smaller as the moisture content was decreased by drying. Bond’s constants and the work index showed lower values as the moisture content decreased. A sigmoid model accurately described the grinding kinetics of the black soybean powder (R 2 &gt; 0.90). The parameters in the sigmoidal models were useful to explain the effect of moisture content during grinding. However, at higher moisture contents, the sigmoid model did not accurately fit the grinding kinetics. The grinding characteristics of black soybeans showed a strong dependence on moisture content. Adjusting the moisture contents of black soybeans using a pretreatment such as drying is very important to control the grinding characteristics, including the energy consumption and the average particle size, during grinding.

Grinding and combustion characteristics of woody biomass for co-firing with coal in pulverised coal boilers

This paper presents results of grinding experiments and development of woody biomass mill for co-firing in pulverised coal fired boilers. Woody biomass co-firing with coal is already realised since it can be easily handled as a carbon–neutral fuel. Three steps have been carried out to understand the grinding and combustion characteristics of woody biomass. A suitable mill type for woody biomass grinding has been sought in laboratory-scale experiments. The selected industrial-scale mill has been modified to increase the capacity.The objective of this experimental study is to establish and demonstrate the woody biomass firing system including mill and burner for pulverised coal fired boilers. Both, laboratory- and industrial-scale measurements, provide good understanding of woody biomass grinding and firing performance. The proper burner arrangement is found by use of Computational Fluid Dynamics (CFD) to maintain high burnout efficiency in the boiler. The study proves that the proposed mill and burner positioning is promising to utilise woody biomass with high co-firing ratio. The combination of furnace experiments and CFD modelling results in a satisfying specification of a co-firing system for woody biomass with pulverised coal in sufficient ratio whilst reducing CO2 emissions.

An experimental study on grinding parameters for manufacturing PCD micro-milling tool

Micromachining has become a necessary manufacturing process. Micro-milling tool and its evolution play a vital role in the development of micromachining. This study optimizes the grinding process of polycrystalline diamond (PCD) compact for manufacturing PCD micro-tool. The optimization is conducted by using four parameters, i.e., grain size of PCD compact, grain size of abrasive wheel, grinding speed, and feed rate designed by the Taguchi orthogonal array. The study then evaluates two grinding characteristics, i.e., grinding forces and cutting edge radius of the PCD compact. The results of ANOVA show that the most influential parameter on grinding PCD compact is the grain size of the PCD compact, followed by the grain size of the abrasive wheel, feed rate, and grinding speed. As an example, a quadrilateral PCD micro-milling tool with a cutting edge diameter of 80 μm is fabricated by using the optimized parameters.

소결방법에 따른 질화알루미늄의 연삭 가공 특성에 관한 연구

In this study, using AlN materials produced by two different sintering techniques, grinding experiments were performed under various grinding conditions, including different table speeds and cut depths. In order to measure the grinding force, a tool dynamometer was used. Surface roughness measurements and a digital microscope were also was used. The grinding forces were higher at a higher table speed and a higher cut depth. The experimental results show that the grinding characteristics of the two workpieces are similar.

Research on Path of Contact Wheel for Ruled Blade Grinding

Blade is one of the important components in aero-engine, turbine, and wind generators. The quality of the blades has big influence on the performance of the machine. So high profile accuracy and low surface roughness were put forward. Ruled blade is just one of the blades of aero-engine, which has simple profile and little distort. This blade was grinded by two sides together in the paper. Therefore, in this thesis, the main objects are as fallow: firstly, according to the characteristics of the abrasive belt grinding, analysis the selection of grinding distance for the blade. Secondly, established the model of contact wheel compare grinding system, derived the range of wrap angle of contact wheel, and then two region were make out, one is the region can be directly grinding, and another region which may lead to wheel interference. At last the grinding path of the center of the contact wheel was obtained by calculated the blade model.

Particle Size Characteristics of Ground Soy and Red Gram

Grinding characteristics of soy and red gram were compared employing single- and two-stage grinding in a mixer grinder. The initial size as well as hardness of soy (˜216 N) and red gram (˜220 N) were nearly equal. However, final particle size of red gram (61 μm) was much lower than soy (255 μm), indicating that red gram was relatively easier to grind. Analysis of microstructure indicated that typical internal structure and intercellular forces could play a significant role in determining the grinding characteristics of individual grains. With the same amount of energy input (200 kJ/kg), size reduction ratio in soy increased from 12 to 16 during two-stage grinding. Energy and particle analyses revealed that a two-stage segregated grinding is suitable for soy while a single-stage grinding is adequate for red gram. Classical dry grinding laws were applicable after initial break up suggesting their suitability for secondary grinding of soy and red gram.

임플란트 시술용 지르코니아 소재의 연삭가공 성능 평가에 관한 연구

3.2YSZ melted by the `skull melting` method has good physical properties and does not undergo low-temperature degradation. Due to its excellent physical and mechanical properties, skull-melted 3.2YSZ has been developed as a dental implant material. In this study, a porous, resin-bonded diamond wheel was created and its grinding characteristics were compared with those of traditional nonporous wheels using skull-melted 3.2YSZ. The experimental results indicate that the porous, resin-bonded diamond wheel requires less grinding force and power. In addition, the porous, resin-bonded diamond wheel requires a greater degree of roughness.

Torrefaction of wheat and barley straw after microwave heating

Microwave irradiation was used in this study for the torrefaction of wheat and barley straw. The torrefaction effect was studied by varying the microwave power level (200–300W), reaction time (10–20min) and moisture content of biomass (5–15%). Mass yield and energy yield of the torrefied biomass was determined. Fuel properties like H/C and O/C ratio were assessed from elemental composition. Grinding characteristics and hydrophobicity of the torrefied sample were studied and compared with the raw biomass. Barley straw tended to carbonize more under microwave irradiation with 29.1% increase in the C content against 16.2% in the case of wheat straw when torrefied at 300W for 20min. Both H/C and O/C ratio decreased with increase in power and reaction time. The energy density increased by 14–15% in wheat straw and 21–23% in barley straw under suitable reaction condition. Mass and energy yields were 64.0–97.8% and 73.8–98.4%, respectively for wheat straw. In barley straw, mass and energy yields were 42.7–97.4% and 52.5–97.3%, respectively. Moisture content of the biomass did not affect the reaction as much as other parameters and the mass yields were comparable between different moisture contents. Grindability of the biomass improved significantly after torrefaction. The particle size ratio between torrefied and untreated straw after grinding was 0.66 and 0.61 for wheat and barley, respectively. The torrefied biomass was more hydrophobic and the moisture uptake was reduced by 61–68% under suitable torrefaction condition. Microwave irradiation can be used effectively for torrefaction of the two biomass investigated at moderate power and short process time.

Tribological characteristics in high-speed grinding of alumina with brazed diamond wheels

In this work, two brazed diamond wheels fabricated by brazing in vacuum were used to grind alumina at different grinding speeds. During the process, the horizontal and vertical grinding forces were measured by a force measurement device. The grinding forces, specific grinding energy, and friction in grinding of alumina at low and at high speeds were investigated. The results show that the friction coefficient decreases with the increase of the grinding speed and also relates to the grinding mode. A nearly proportional relationship between grinding power per unit width (Pm) and the rate of plowed surface area generated per unit time per unit width (Sw) reveals the effects of friction in grinding and most of the grinding energy is expended by friction. The surface energy per unit area generated by plowing friction (Js) for high-speed grinding is found to be lower than for low-speed grinding.