Grinding Characteristics Research Articles

Effect of CMC Addition on Grinding Characteristics of Hardwood Bleached Kraft Pulp

Effect of CMC Addition on Grinding Characteristics of Hardwood Bleached Kraft Pulp

Sleep Bruxism-Tooth Grinding Prevalence, Characteristics and Familial Aggregation: A Large Cross-Sectional Survey and Polysomnographic Validation.

Sleep bruxism (SB) is characterized by tooth grinding and jaw clenching during sleep. Familial factors may contribute to the occurrence of SB. This study aims are: (1) revisit the prevalence and characteristics of SB in a large cross-sectional survey and assess familial aggregation of SB, (2) assess comorbidity such as insomnia and pain, (3) compare survey data in a subset of subjects diagnosed using polysomnography research criteria. A sample of 6,357 individuals from the general population in Quebec, Canada, undertook an online survey to assess the prevalence of SB, comorbidities, and familial aggregation. Data on familial aggregation were compared to 111 SB subjects diagnosed using polysomnography. Regularly occurring SB was reported by 8.6% of the general population, decreases with age, without any gender difference. SB awareness is concomitant with complaints of difficulties maintaining sleep in 47.6% of the cases. A third of SB positive probands reported pain. A 2.5 risk ratio of having a first-degree family member with SB was found in SB positive probands. The risk of reporting SB in first-degree family ranges from 1.4 to 2.9 with increasing severity of reported SB. Polysomnographic data shows that 37% of SB subjects had at least one first-degree relative with reported SB with a relative risk ratio of 4.625. Our results support the heritability of SB-tooth grinding and that sleep quality and pain are concomitant in a significant number of SB subjects.

Comparison of Grinding Characteristics of Converter Steel Slag with and without Pretreatment and Grinding Aids

The converter steel slag cannot be widely used in building materials for its poor grindability. In this paper, the grinding characteristics of untreated and pretreated (i.e., magnetic separation) steel slag were compared. Additionally, the grinding property of pretreated steel slag was also studied after adding grinding aids. The results show that the residues (i.e., oversize substance) that passed a 0.9 mm square-hole screen can be considered as the hardly grinding phases (HGP) and its proportion is about 1.5%. After the initial 20 min grinding, the RO phase (RO phase is a continuous solid solution which is composed of some divalent metal oxides, such as FeO, MgO, MnO, CaO, etc.), calcium ferrite, and metallic iron phase made up most of the proportion of the HGP, while the metallic iron made up the most component after 70 min grinding. The D50 of untreated steel slag could only reach 32.89 μm after 50 min grinding, but that of pretreated steel slag could reach 18.16 μm after the same grinding time. The grinding efficiency of steel slag was obviously increased and the particle characteristics were improved after using grinding aids (GA), especially the particle proportions of 3–32 μm were obviously increased by 7.24%, 7.22%, and 10.63% after 40 min, 50 min, and 60 min grinding, respectively. This is mainly because of the reduction of agglomeration and this effect of GA was evidenced by SEM (scanning electron microscope) images.

Analysis on the Effects of Grinding Wheel Speed on Removal Behavior of Brittle Optical Materials

It is often desired to increase the machining rate while maintaining the desired surface and subsurface integrity during fabricating high-quality optical glass components. This paper proposed a high-speed high-efficiency low-damage grinding technology for machining brittle optical materials, which consists of three grinding processes: rough grinding, semifinishing grinding, and finishing grinding. Grinding characteristics are investigated with respect to grinding forces, specific cutting energy, surface roughness, ground surface quality, subsurface damage, and material removal mechanisms in grinding of fused silica optical glasses with this technology at grinding speeds of up to 150 m/s. These indications are thoroughly discussed by contacting the undeformed chip thickness. The results indicate that the level of these indications is significantly improved with an increase in the wheel speed due to the decrease of the undeformed chip thickness. It is also found that the improvement of ground surface quality is limited when the wheel speed increases from 120 m/s to 150 m/s, which may be due to the influence of vibration caused by the higher wheel speed. For different grinding processes, these results are also substantially improved with the change of grinding conditions. It is found that the material removal mechanism is dominated by brittle fracture at rough and semifinishing grinding processes, while ductile flow mode can be observed at the finishing grinding process. There are some differences between the experimental results and the previous predicted model of subsurface damage depth.

Fundamental Investigation of Ultrasonic Assisted Pulsed Electrochemical Grinding of Ti-6Al-4V

Aiming at the development of a novel grinding technology for the highly efficient machining of difficult to machine materials such as Ti-6Al-4V, an ultrasonic assisted pulsed electrochemical grinding (UAECG) method was proposed. The current work is to reveal the fundamental grinding characteristics of the UAECG of Ti-6Al-4V by experimentally investigating the effect of vibration amplitude on grinding forces, actual material removal and work-surface roughness under different process parameters such as the input voltage and rotational speed. Summarizing the obtained results revealed that the grinding forces in UAECG are significantly smaller than those in conventional grinding (CG).

Grinding Characteristics of Waspaloy with High-Speed Reciprocation Grinding

Grinding machines that employ a high-speed reciprocating worktable or wheel head are known as high-speed reciprocation grinding. Grinding heat generated in the high-speed reciprocation grinding process is low. Therefore, it is considered that the high-speed reciprocation grinding is suitable for grinding material of low thermal conductivity. In this study, the high-speed reciprocation grinding is applied to grind nickel-based super alloy “Waspaloy” which is known as difficult-to-cut material. And grinding characteristics of Waspaloy are investigated. As a result, it is found that the effect of grinding heat is smaller than the effect of grain depth of cut in grinding process of Waspaloy.

Grinding characteristics in high-speed grinding of boron-diffusion-hardened TC21-DT titanium alloy with vitrified CBN wheel

An investigation was undertaken to seek the grinding characteristics in the grinding of boron-diffusion-hardened TC21-DT titanium alloy using a vitrified CBN wheel. The grinding forces and temperature were measured and the morphological properties of ground surfaces were examined. The results indicated that, for conventional speed grinding, material removal was mainly dominated by ploughing coupled with somewhat shearing. For the high-speed grinding process, due to the different mechanical properties between titanium substrate and hard phase particles, the strain gradient effect in the primary deformation zone (PDZ) appeared to arise. Moreover, when the grinding speed was increased to 120 m/s, chip formation by the shearing process was accounted for a positive role, resulting in a considerable improvement in the ground surface roughness. In addition, the modeling of the specific grinding energy in the PDZ, during the grinding process, was provided, and the general trend predicted by the model was found to be the same as that investigated by experimental results.

Influence of Stone Chakki Settings on the Characteristics of Whole Wheat Flour (Atta ) and its Chapati Making Quality

Whole wheat flour (atta) was produced by varying the settings of stone chakki and studies were carried out on grinding characteristics of wheat, energy efficiency, atta characteristics and its suitability for chapati making quality. Significant difference was observed in processing parameters and specific energy requirement with variations in settings. Reduction ratio value which is the ratio of average size of feed and average size of product was 7.55 and 81.08, respectively, for two extreme settings. Kicks law was applicable in present study and values of Kicks constant were found to be increased linearly with the fineness of flour and were found in the range of 71.22 and 92.56 kJ/kg. Flour fineness, damaged starch, water absorption and the colour of atta improved with decreased gap. Chapati with better acceptable characteristics for sensory, texture and storage parameters were obtained from atta with damaged starch of about 18 and 80% water absorption. Practical Applications Overall quality of chapati prepared from stone chakki produced atta is found to be better than that from other type of grinders. Industrially, packaged atta is produced using stone chakkis and this product is witnessing an increased demand over the years. As of now, no quality parameters are defined in terms of particle size distribution, damaged starch and the water absorption of atta for desired chapati making quality, because of which milling parameters are not standardized to produce atta using stone chakkis on the industrial scale. Present study is carried out to establish some guidelines for milling of wheat that will be helpful for flour millers in order to avoid unnecessary expenditure on energy and time in creating smaller particles than are required for atta with better chapati making quality.

Caracterización fisicoquímica de cuatro especies de agaves con potencialidad en la obtención de pulpa de celulosa para elaboración de papel

<p>El objetivo general de este trabajo fue encontrar un nuevo valor agregado a las hojas de las agaváceas, desecho de la agroindustria. Se estudiaron cuatro especies de agaves de tres estados de la república mexicana: Agave angustifolia (Oacaxa), Agave tequilana (Jalisco), Agave salmiana y Agave lechuguilla (Hidalgo). Luego de una clasificación taxonómica, fenológica, ecológica y etnobotánica (basados en morfología comparada), se sometieron a diversos análisis físicos (humedad, molienda, tamizaje, granulometría y características foliares, MEB) y químicos (cenizas grasas y aceites, proteínas, análisis TGA y DTGA, así como FTIR). Las especies de A. angustifolia y A. tequilana son las que presentan un óptimo tamaño de fibra para la elaboración de papel. Corresponde también a los mayores porcentajes de celulosa (44.3% y 36.8%) por DTGA. Del análisis proximal, se evidencia que las dos especies definidas como mejores para la obtención de pulpa de celulosa, presentan pequeñas diferencias significativas en contenidos de grasas, proteínas, material solubilizable en agua caliente (AT) como en solución moderadamente alcalina y/o alcohólica.</p>

An analysis of the energy split for grinding coal/calcite mixture in a ball-and-race mill

Interactions among components in the heterogeneous grinding would change energy consumed characteristics of components if compared with those in the single-component breakage. In this paper, energy split phenomenon for the coarse grinding of super clean anthracite coal (SCAC)/calcite mixture of 2.8–2mm in the ball-and-race mill is investigated. Before the analysis of experimental results, accuracy of energy split function in terms of time-dependent breakage rate is first discussed. Energy consumed characteristics of grinding in the ball mill and ball-and-race mill are also compared. Breakage model of product t10 (yield of progenies in −0.237mm) vs specific energy is used to describe the energy-size reduction of the single-component and multi-component grinding. Interaction between components is reflected by the comparison of specific energy of components in mixture and single breakage to yield the same product t10. Based on the energy balance, energy split factors of components in different time and mixed conditions are first determined. This parameter shows no change with time. Calcite increases the grinding efficiency of SCAC significantly, with the energy split factor for SCAC ranging from 0.68 to 0.73, which means less specific energy is consumed by SCAC to yield the same t10 if compared with the single breakage. As the volumetric ratio of calcite increases in mixture, grinding energy efficiency decreases and energy split factor of calcite increases from 1.70 to 1.83. Soft material reduces the grinding energy efficiency of hard one in the multi-component breakage.

Size Reduction Characteristics of Yellow Poplar in a Laboratory Knife Mill

ABSTRACT Size reduction is one of the major pre-processing operations in using biomass as a source of energy or rawmaterials for forest products industry. The grinding characteristics of dried yellow poplar wood chips wereinvestigated using laboratory knife mill with three different screen aperture diameters to provide the basicinformation for the optimizing of size reduction processes in biomass industry. Average specific energy con-sumptions were 0.157, 0.137, and 0.093 Wh/g for the screen aperture diameters of 5.0, 7.5, and 9.0 mm, respectively. According to the results of size distribution analysis of ground particles, the sizes of the most of ground particles were much smaller than the aperture diameters of the screens installed on knife mill used in this study. Keywords : size reduction, biomass, knife mill, specific energy consumption for milling, particle size distribution, Liriodendron tulipifera L. 1 Date Received November 19, 2015, Date Accepted December 28, 2015 2 College of Agriculture and Life Science, Chonnam National University, Gwangju 61186, Republic of Korea

Effect of Different Thermal Treatments on Grinding Characteristics, Granular Morphology and Yield of Ready‐to‐Eat Wheat Grits

AbstractReady‐to‐eat wheat grits are highly fibrous food product which was prepared from wheat by using different thermal treatments (Parboiling, pressure parboiling and roasting methods). The effects of these treatments on hardness, alkali spreading value (ASV), granular morphology, protein digestibility (PD), grit yield, grinding constants and specific power consumption (SPC) were studied. However, the particle size distribution, grinding constants and SPC were also studied with the different feed rates of each experiment. The maximum grits yield (77%), SPC (0.061 kWh/kg), hardness (6.67 kg), were found in pressure parboiling. The highest PD (78 %) and ASV were observed in roasting method. Although, a significant variation was found in grinding constants with the different feed rates and heat treatments. The roasting method was found to have overall desired values of PD (78%), granular morphology, ASV (7), hardness (3.21 kg) and SPC (0.040 kWh/kg).Practical ApplicationsReady‐to‐eat wheat grits are highly fibrous food product and prepared from wheat by using different thermal treatments. It plays an important role in addressing the constipation problems. The power consumption and product quality are key parameters for producer and consumer. This study has generated sound thermal processing and energy consumption data and health benefits which can be used by food industries and consumers.

ELID grinding characteristics of SiCp/Al composites

In this study, electrolytic in-process dressing (ELID) grinding experiments were conducted on SiCp/Al composites, and the effects of grinding depth and feed speed of work table on grinding force, surface roughness, and surface morphology were investigated. The experimental results showed that the fluctuation range of grinding force and grinding force ratio Cf under ELID condition were smaller than that of the same grinding parameters under wet grinding condition. Additionally, ELID grinding is effective in providing the uniformly grit protrusion and chip storage space. SiC particles were removed in ductile mode, and the brittle fracture of SiC particles were reduced substantially. The high integrity surface of the SiCp/Al composites could be obtained under ELID condition.

Characteristics in Grinding of YVO<sub>4</sub> with a Resin Bond Diamond Wheel

An investigation was undertaken to explore the grinding characteristics in grinding of yttrium vanadata (YVO4) crystal by using a resin diamond wheel. The grinding forces and surface roughness were measured and the morphological features of ground workpiece surfaces were examined. The results indicate that the depth of cut is the leading factor in affecting grinding forces whereas the surface roughness is mainly governed by the grinding speed. The material removal mechanism was found to be dominated by brittle fracture mode at conventional grinding speeds, and gradually transfer to ductile flow mode under higher grinding speeds, which is greatly related to the maximum undeformed chip thickness.

Grinding characteristics, gravimetric properties and energy constant calculations of dried and roasted dehulled soybean splits

The dried and roasted dehulled soybean splits were conditioned to 3 ± 0.02% (db). These samples were ground with hammer mill having different screen aperture sizes (1.5,1.2 and 0.7 mm) and feed rates (18,14,10 kgh1) at constant rotor speed (3000 rpm). The dimensions (major, medium and minor), geometric mean diameter, sphericity, surface area, thousand grains mass and bulk density of dried and roasted soybean sample were found to be 2.03 - 8.3 mm and 2.12 - 9.13 mm, 5.15 mm and 5.74 mm, 53.18% and 53.28%, 78.39 mm2 and 95.11 mm2,46.78 g and 46.01 g, 601.66 kg m3 and 484.58 kgm3, respectively. The size reduction ratio and grinding effectiveness was maximum at 18 kg h1 feed rate and 1.2 mm screen aperture size. The specific energy consumptions and power consumption decreased froml52.06 kJ kg1 to 15.36 kJkg1 and 69.12 kJ kg1 to 15.36 kJ kg1; 1612.8 W kg1 - 1267.2 W kg1 and 1382.4 Wkg1-1267.2 W kg1 with increased feed rate (10 kgh1 -18 kgh1) for screen aperture size (0.7 mm-1.5 mm) for dried and roasted soybean sample, respectively. Also, the energy constants values showed a decreasing trend with feed rate and screen aperture size range

Experimental research on the belt grinding technology for the real-R edge of the aero-engine precision-forging blade

Because of the special characteristics of aero-engine precision-forging blade edge, the edge profile shape errors are easily caused by using conventional processing methods. The purpose of this research is to improve real-R profile shape errors and also exploring the belt grinding mechanism for the high-strength materials. Firstly, the grinding characteristics and process planning to the blade real-R edge are analysed. And then, the methodology of EBG with CBN belt is illustrated, at the same time, the control equation for EBG is established. Finally, the method of EBG with CBN belt is analysed by the experiment investigated to the aero-engine precision-forging blade, comparing to the method of hand. The experimental results show that the real-R profile shape errors ≤ ± 0.07 mm, and the real-R shape smoothing, profile clear and the inter sectional surface smooth transition. It is verified that the method of EBG is better than the conventional method.

研削砥石作業面トポグラフィのステレオ視法援用機上3次元計測システムに関する研究

The abrasive grain shape and its distribution in the grinding wheel have an influence on the grinding characteristic of the wheel. Therefore, we aim to develop the on-machine 3D measurement system by binocular stereopsis for abrasive grain shape and its distribution in the grinding wheel. In this paper, the 3D shape measurement is carried out using the omnifocal images. Comparing between the ratios of outlier by use of optical filters, we aim to improve the stereo pair images by decrease the outlier of matching. Thereafter, we analyzed the grinding wheel surface 3D topography and the abrasive behavior by performing tracking observation of the grinding wheel working surface in the grinding process by using this system.

ハイレシプロ研削法による耐熱合金の研削加工

Grinding machines that employ a high-speed reciprocating worktable or wheel head are known as high-speed reciprocation grinding. Grinding heat generated in the high-speed reciprocation grinding process is low. Therefore, it is considered that the high-speed reciprocation grinding is suitable for grinding material of low thermal conductivity. In this study, the high-speed reciprocation grinding is applied to grind nickel-based super alloy “Waspaloy” which is known as difficult-to-cut material. And grinding characteristics of Waspaloy are investigated. As a result, it is found that the effect of grinding heat is smaller than the effect of grain depth of cut in grinding process of Waspaloy.

Effect of microwave irradiation on the grinding characteristics of Ximeng lignite

The grinding characteristics of untreated and microwave-treated Ximeng lignites (XLs) were investigated, and the effects of microwave irradiation time, particle size range, and initial moisture were studied. The mass fraction and particle size distribution of the fine ground product with <0.154mm particle size range of untreated and microwave-treated XLs were obtained. According to the analysis results of proximate, scanning electron microscopy and nitrogen absorption, the dominant mechanisms that improved the grindability of XL with high moisture under microwave irradiation included the rapid removal of moisture within the XL and the destruction of the pore structure induced by the steam jet flow generated with moisture removal. Microwave irradiation could improve the grindability of XL with high moisture, thus increasing the breakage rate of microwave-treated XL and mass fraction of the fine ground product significantly. The particle size distributions of the fine ground products of untreated and microwave-treated XLs changed slightly. With increasing microwave irradiation time, initial moisture, and particle size range of XL, the increment in the grindability of microwave-treated XL increased. When XL was treated at low microwave power, the microwave irradiation time was extended properly to avoid the accumulation of moisture on the surface. Therefore, the grindability of microwave-treated XL improved significantly.

Characteristics in Grinding of YVO&lt;sub&gt;4&lt;/sub&gt; with a Resin Bond Diamond Wheel

Characteristics in Grinding of YVO&lt;sub&gt;4&lt;/sub&gt; with a Resin Bond Diamond Wheel