Papers by Keyword: Dry Grinding

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Authors: Alao Abdur-Rasheed
Abstract: Conventional diamond cutting of ferrous materials is rarely economical due to the rapid tool wears which result from diffusion and graphitization of the tools. Conventional machining of hard-brittle materials like silicon and germanium results in surface and subsurface damage due to their brittle fracture. Although ductile mode machining (DMM) concept can be used to have a flawless machining on these materials but the mirror surfaces can only be realized on expensive ultraprecision machine tools because the critical depth of cut must be on the order of 1μm or less. Furthermore, there is a need to eliminate or reduce the use of cutting fluids during machining due to their attendant ecological hazards. However, grinding is one of the most difficult processes with regard to eliminating cutting fluids. Vibration assisted machining (VAM) can be used to minimize the problems enumerated above. VAM combines precision machining with small-amplitude tool vibration to improve the fabrication process. It has been applied to a number of processes ranging from turning, drilling to grinding. Therefore, this paper discusses DMM, the general overview of VAM, the basic kinematics of one-dimensional VAM; the advantages derived from using VAM and the ability of VAM to machine brittle materials in the ductile regime at increased depth of cut are described. Finally, the research directions in VAM are outlined.
Authors: Jia Jia Chen, Yu Can Fu, Qing Shan He, Wei Zhang, Yan Bin Zhu
Abstract: The core idea of the existing cooling methods in grinding process is making a large quantity of coolant into the contact zone. However, the practical quantity of coolant injected in the grinding zone is limited, and the large amount of coolant employed can cause pernicious effect to human health and the environment, and will largely increase the expenses. In order to solve this problem, an environmental friendly idea about enhancing heat transfer in the contact zone based on heat pipe technology is put forward in this paper. The new system, heat pipe grinding wheel (HPGW), based on this high-efficiency cooling technology is developed and its heat transfer principle is illustrated. Eventually grinding experiments with HPGW were carried out to verify the cooling effect by comparing with non-HPGW in grinding plain carbon steel. Results show that using HPGW can significantly reduce the grinding temperature with no coolant.
Authors: Amir Daneshi, Bahman Azarhoushang
Abstract: Structuring of the grinding wheels is a promising method to reduce the forces involved in grinding, especially during dry grinding. In this paper, one of the methods of grinding wheel structuring is presented. The structuring process was modeled to find the corresponding dressing parameters for the desired structure dimensions. The cylindrical grinding operation with the structured wheels was simulated to produce a spiral free ground surface. Afterwards, the dry grinding experiments with the structured and non-structured wheels were carried out to evaluate the efficiency of the structured wheels. The results revealed that the grinding forces can be reduced by more than 50% when the grinding wheels are structured, while the surface roughness values increase by 80%.
Authors: Hasan Ergin, Mert Kiliç, Emrah Durgut, Kagan Kayaci, Ali Altintaş, Yildiz Yildirim
Abstract: In ceramic production, there are around 5-8 % of floor tile defects occurred due to unsuitable body compositions or operational failure. The reuse of those fired products creates problems due to the difficult grindability features. These kinds of wastes are stored near factories and create vital environmental problems. There are some attempts to utilize these waste materials by adding to the recipes at small amounts. However, the grinding efficiency of the system is detrimentally affected and the grinding costs increases sharply. The aim of this work is to determine the dry grinding properties of floor tile wastes in order to utilize more and economical manner in the process. This paper includes grinding experiments in the laboratory dry ball mill. It is driven by inverter motor and control panel that allow to adjust the mill rotational speed, measure the grinding time and required energy consumption. Systematic grinding tests were carried out to observe the effect of feed particle size, feed rate, material moisture and mill rotational speed on the grinding efficiency. Finally, it was sought to use the dry prepared powder in glazed porcelain body composition. It was found that there are no inconvenient results on the sintered body up to usage of 20%.
Authors: Chao Chen, Xing Yong Gu, Yun Xia Chen, Ting Luo
Abstract: In order to improve the performance of gypsum mould, dry grinding process was applied to the pretreatment of gypsum powder and the effect of the ball-milling time on the performance of gypsum powders was mainly studied in our work. X-Ray powder diffraction (XRD) and scanning electron microscope (SEM) were employed to characterize the phase compositions and microstructures of gypsum mould. The results show that the initial and final setting time of gypsum slurry reduces with the increasing of ball-milling time. But the initial and final setting time changed slightly when the ball-milling time was extended to 1 hour or more. Furthermore, the water absorption of gypsum moulds made by the pre-grinded gypsum powders was increased by 42.0 percent in the case of 2 hours’ grinding time, yet the flexual strength of the mould was slightly decreased by 12.5 percent. The main phase of gypsum powder was unchanged, but decrystallization degree increased after dry grinding process. Meanwhile, the crystal orientation and particle aggregation of the gypsum powders were destroyed, and the particle length of that was shortened. As a result, the gypsum moulds obtained by the as-treated gypsum powders have high porosity and water absorption.
Authors: Kazuhito Ohashi, Soziro Murakawa, Shinya Tsukamoto
Abstract: In dry grinding of hard carbon parts, the grinding performance of wheel is remarkably lost by carbon chips loading on wheel surface. The deterioration in grinding performance of wheel affects the grinding accuracy and efficiency. Generally, the grinding performance of loading wheel recovers by dressing. However, the dressing is not suitable from a viewpoint of the wheel life and the production cost because many abrasive grains having sharp edges under loading carbon chips on wheel surfaces are lost by dressing. In this study, we propose the application of dry ice blasting as a removal method of loading carbon chips. The dry ice is little influence on the working environment because of the quick sublimation of dry ice particles to carbon dioxide. In addition, the dry ice blasting might be suitable for the chip removal method because the dry ice doesn’t remain on wheel surfaces after blasting without the damage of wheel surfaces. The dry ice blasting tests of resinoid bond diamond wheel surface with no grinding performance by loading carbon chips are carried out, and the effects of dry ice blasting on removal of loading carbon chips are investigated, analyzing the protrusion height of abrasive grains, the impact pressure in the dry ice blasting and so on.
Authors: Taghi Tawakoli, Engelbert Westkämper, Bahman Azarhoushang
Abstract: The total removal of grinding wheel material includes two main parts. The larger of the two is the result of dressing and truing operation and the other relatively small part is due to the wheel wear which takes place during the actual grinding process. The frequency of dressing and truing operations depends on the cutting conditions, wheel characteristic, etc. However in dry grinding as there is no cutting fluid to transfer the heat from the contact zone, the wheel wear during grinding and the frequency of dressing is much higher due to the higher grinding forces and temperatures. Vibration grinding reduces wear of the grinding wheel during the process considerably and decreases the frequency of dressing operation significantly. Hence it increases the efficiency of the process and reduces the cost. The investigation carried out in the KSF institute shows the improvement on the surface roughness, reduction of the grinding forces, thermal damage of the ground surface and radial wear of the grinding wheel in case of using vibration grinding comparing to conventional grinding. The designed and developed ultrasonically vibrated workpiece holder and the experimental investigation show a decrease of up to 80% of radial wear of the grinding wheel.
Authors: Yuki Ohta, Soziro Murakawa, Kazuhito Ohashi
Abstract: In dry grinding of hard carbon parts, the loading by carbon chips on wheel surface occurs in early grinding process, and the grinding performance of wheel is extremely declined. The deterioration affects the grinding accuracy and efficiency. Therefore, loading is one of the problems that must be resolved for high efficiency and high quality grinding of carbon. Generally, the grinding performance of wheel is recovered by the dressing. However, it’s not suitable from a viewpoint of the wheel life and the production cost because available abrasive grains possessing sharp edges under loading carbon chips on wheel surface are lost by dressing. In this study, we propose the dry ice blasting for removing loading carbon chips on wheel surface. The dry ice particles impact on pressed carbon chips with high pressure and sublimate to carbon dioxide quickly. Therefore, it is little influence on working environment because the dry ice doesn’t remain on wheel surfaces after blasting without the damage. In this report, we carry out the blasting tests of resinoid bond diamond wheel surface without grinding performance by loading carbon chips, and analyzed the effect of nozzle processing speed and nozzle feed pitch on recovering abrasive protrusion. The effective dry ice blasting conditions are investigated for high efficiency removal of loading carbon chips, analyzing the protrusion height of abrasive grains.
Authors: Qi Cheng Lao, Zhi Yi Shang
Abstract: In the grinding of high speed steel, the high temperature grinding zone often leads to poor surface quality such as grinding burn, micro-cracks and tensile residual stresses. In the paper, the cooling-air technology was adopted to study the grinding of high speed steel. The experimental results show that cooling-air grinding can effectively restrain the grinding burns, reduce the surface roughness value and improve the surface quality in comparison with dry grinding.
Authors: Kazuhito Ohashi, Yuya Takata, Shinya Tsukamoto
Abstract: The grinding performance of wheel remarkably decreases by the wheel loading in dry grinding of precision hard carbon parts. When the wheel loading occurs, the dressing is carried out to remove loading chips for generation of the grinding performance. However, many abrasive grains, which have enough cutting ability under loading chips, are removed in dressing. We therefore have developed the wheel surface cleaning using adhesive films without dressing to remove loading carbon chips on wheel surfaces in our previous reports, and the cleaning could achieve the lean regeneration of grinding performance of fine grade diamond wheels. The removing ability of loading chips is improved by increasing the peeling speed of adhesive film, the pressing time of adhesive films or the number of pressing time. However the optimum cleaning condition has not been investigated. In this report, from the viewpoint of efficiency in the treatment, we therefore investigate the optimum rolling press process of adhesive film on loading disc wheel surfaces in dry grinding of carbon. The optimum treatment processes are experimentally made clear, analyzing SPa of cleaned wheel surfaces, which is one of surface roughness parameters having the correlation with the protrusion height of abrasive grains. Furthermore, the effect of the treatment on regeneration of grinding performance is experimentally verified by grinding tests of hard carbons.
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