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In grinding operation, cutting fluid is utilized for lubrication, cooling, chip removal from contact zone and also cleaning of grinding wheel. Despite these advantages, grinding fluids make many economic and environmental issues. On the other hand, dry grinding generally leading to thermal damages and reduction of surface quality level. Minimum Quantity Lubrication (MQL) technique is a new approach to elimination or reduction of cutting fluids that improves grinding performance by efficient penetration to the cutting zone. In this paper, in order to investigate the effect of MQL on grinding of steels, raw and hardened High Speed Steel have been selected. Grinding performance such as tangential grinding force, friction coefficient, roughness and morphology of the ground surface and chip form in three states of dry, conventional fluid and MQL have been studied and compared. The results show that MQL technique in comparison with the others lead to improvement of surface quality and also reduction of tangential grinding force and friction coefficient in hardened steel, but in the case of raw steel despite of reduction of tangential grinding force and friction coefficient, the surface quality is worst.

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Consumption of cutting fluids imposes high costs on industry. These cutting fluids contaminate the environment and are harmful to human health. Minimum quantity lubrication technique (MQL) is a new approach to reduction of cutting fluids consumption, improving efficiency of cutting fluid at machining zone and using harmless fluids. However, this technique faces cooling limitation in grinding. The purpose of this study is an accurate study of heat transfer mechanism in minimum quantity lubrication technique by its temperature numerical simulation and improving the cooling ability of its air jet by using a simple and inexpensive vortex tube. For this purpose, a system was designed and manufactured to measure the convection heat transfer coefficient of different conditions of MQL environments. The result of convection heat transfer tests shows 95% share of compressed air in heat transfer and also air pressure is a more important factor than temperature in cooling process. The result of temperature numerical simulation shows that by increasing pressure, the increasing rate of convection heat transfer coefficient decreases; also, the cooling ability temperature of the vortex tube at low thermal power is tangible. In grinding of soft steel, the minimum quantity lubrication technique with cold air (CAMQL) in comparison with other methods lead to significant reduction of tangential grinding force and friction coefficient, but in general, except in the case of optimum condition which has the highest heat transfer coefficient, surface finish is worse which relate to low heat transfer coefficient of gases at low pressures.

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Minimum quantity lubrication (=MQL) technique has many technological and economic advantages in grinding operation. It not only improves general grinding performance such as surface integrity, grinding forces and wheel wear but also, it is eco-friendly technique because of its small consumption of cutting fluid. Despite these advantages, MQL technique has a serious thermal problem in grinding operations due to small amount of cooling. To overcome this problem combination of hybrid nanofluid and ultrasonic vibration has been suggested. Nanofluid can increase heat transfer from workpiece/wheel interface due to its high thermal conductivity. Also ultrasonic machining can decrease heat generation due to its reciprocating mechanism and reduction of time and length of contact between grain and workpiece. In this research hybrid Multi Walled Carbon Nano Tubes (=MWCNT) (with high thermal conductivity) and Al2O3 (with good lubrication effect) nanofluid has been utilized. The results have been shown that combination of MQL and UAG leads to decreasing of maximum grinding temperature up to 60.2% in comparison to dry grinding (from 254ºC to 101ºC). Moreover, friction coefficient and tangential grinding force have been reduced up to 35.9 and 69.2 percent respectively. Furthermore, any burning has not been observed with combinations of these techniques while severe burning has been observed in dry grinding. Surface morphology analysis has been shown decrease of plastic deformation and side flow. And finally the generated chips have been shown similarity of cutting mechanism in in the utilized techniques and conventional cutting fluids.

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Due to high ability of built-up edge formation during aluminum machining, this study aim to reducing adhesive wear and increasing surface integrity of 5052 aluminum alloy workpiece has been focused on creating different surface texture on tungsten carbide cutting tool. For this purpose, four types of micro-grooves such as parallel and perpendicular to cutting edge and also pit and cross mode have been created on rake face by laser machining process. In addition to the types of texture, three methods of cooling-lubrication condition include: dry machining, flood mode without pressure and flood mode with high-pressure along with various holder and cutting inserts (with chip-breaker and without chip-breaker) as well as three levels of cutting speed (fixed feed rate and depth of cut) were considered as process variables. The experimental results obtained from surface roughness survey of the machined parts along with prepared images of optical microscopy from the workpiece surface showed that the presence of parallel micro-grooves significantly improves the cooling-lubrication conditions of the tool-chip surface and its effect on numerical reduction of surface roughness value and reduction of density of defective regions on the workpiece surface is visible. The prepared images by scanning electron microscope (SEM) of the tool rake face showed that the presence of chip-breaker did not significantly effect on reduction of adhesion wear in the machining of aluminum alloy but micro-texture can be largely improved the adhesion wear area compared to non-textured tool (with chip-breaker or without chip-breaker).

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The use of aluminum with a reinforced coefficient to increase this material compared to aluminum is used in the automotive, aircraft, and locomotive industries. This article examines the parameters of the material removal rate (MRR) rate and surface quality in the machining process of composite aluminum in different percentages of SIC. It examines the machining characteristics of end milling operations to obtain minimum surface quality, cutting force, and chip removal rate with maximum material removal rate using gray relational analysis based on the response surface design method (RSM). Twenty-seven experimental runs were carried out based on the response surface design method (RSM) by changing the parameters of spindle speed, feed, and depth of cut in different weight percentages of reinforcements such as silicon carbide (SiC-5%, 10%, 15%). And alumina (5-5% Al2O3) in the aluminum metal base 7075. Gray relation analysis was used to solve the multi-response optimization problem by changing the weights for different responses based on quality or productivity process requirements. The results show that spindle speed and SiC weight percentage are the most important factors that affect the machining properties of hybrid composites.

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The use of aluminum with a reinforced coefficient to increase this material compared to aluminum is used in automotive, aircraft and locomotive industries, in this article, while examining the cutting force and erosion of tools on the machining process of composite aluminum in different percentages of SIC, the machining characteristics are investigated. The end milling operation is performed to obtain the minimum cutting force, tool wear with the maximum removal rate using gray relational analysis based on response surface design method (RSM). Twenty-seven experimental runs were carried out based on the response surface design method (RSM) by changing the parameters of spindle speed, feed and depth of cut in different weight percentages of reinforcements such as silicon carbide (SiC-5%, 10%, 15%). and alumina (5-5% Al2O3) in the aluminum metal base 7075. Gray relation analysis was used to solve the multi-response optimization problem by changing the weights for different responses based on quality or productivity process requirements. Proper selection of input parameters (spindle speed 1000 rpm, feed 0.03 mm/rev, depth of cut 1 mm and 5% SiC) produces high material removal rate with fine surface, less tool wear and low cutting force.

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Due to the significant increase in demand for materials with new capabilities, the use of composite materials is increasing. These materials have unique properties such as high wear resistance and a high strength-to-weight ratio, and are used by engineers in various industries, particularly in the aerospace and automotive sectors. Due to the metallic nature of these materials, the machining process is an integral part in achieving the shape and properties of the final product. Among composite materials, aluminum-based composites are the most widely used in industry. In this study, a methodical was conducted, study including statistical modeling using the response surface method and deriving regression equations of the effect of spindle rotation speed, feed rate, and depth of cut on surface roughness, metal removal rate, and tool wear during machining of A359/B4C/Al2O3 matrix aluminum composite. It was found that an increase in spindle rotation speed, feed rate, and cutting depth increased metal removal. The best combination of parameters that was found to simultaneously minimize the surface roughness and maximize the metal removal rate and minimize flank wear was a spindle speed of 600 rpm, a feed rate of 0.075 mm/rev, and a cutting depth of 0.20 mm