Metal cutting fluids changes the performance of machining operations because of their lubrication, cooling, and chip flushing functions. Typically, in the machining of hardened steel materials, no cutting fluid is applied in the interest of low cutting forces and low environmental impacts. Minimum quantity lubrication (MQL) presents itself as a viable alternative for hard machining with respect to tool wear, heat dissertation, and machined surface quality. This study compares the mechanical performance of minimum quantity lubrication to completely dry lubrication for the turning of hardened bearing-grade steel materials based on experimental measurement of cutting forces, tool temperature, white layer depth, and part finish. The results indicate that the use of minimum quantity lubrication leads to reduced surface roughness delayed tool flank wear, and lower cutting temperature, while also having a minimal effect on the cutting forces.
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The growing demand for higher productivity, product quality and overall economy in manufacturing by machining and grinding, particularly to meet the challenges thrown by liberalization and global cost competitiveness, insists high material removal rate and high stability and long life of the cutting tools. But high production machining and grinding with high cutting velocity, feed and depth of cut are inherently associated with generation of large amount of heat and high cutting temperature. Such high cutting temperature not only reduces dimensional accuracy and tool life but also impairs the surface integrity of the product. In high speed machining conventional cutting fluid application fails to penetrate the chip–tool interface and thus cannot remove heat effectively. Addition of extreme pressure additives in the cutting fluids does not ensure penetration of coolant at the chip–tool interface to provide lubrication and cooling . However ,high-pressure jet of soluble oil, when applied at the chip–tool interface, could reduce cutting temperature and improve tool life to some extent .However, the advantages caused by the cutting fluids have been questioned lately, due to the several negative effectsthey cause. When inappropriately handled, cutting fluids may damage soil and water resources, causing serious loss to the environment. Therefore, the handling and disposal of cutting fluids must obey rigid rules of environmental protection. On the shop floor, the machine operators may be affected by thebad effects of cutting fluids, such as by skin and breathing problems For the companies, the costs related to cutting fluids represent a large amount of the total machining costs. Several research workers state that the costs related to cutting fluids are frequently higher than those related to cutting tools. Consequently, elimination on the use of cutting fluids, if possible, can be a significant economic incentive. Considering the high cost associated with the use of cutting fluids and projected escalating costs when the stricter environmental laws are enforced, the choice seems obvious. Because of them some alternatives has been sought to minimize or even avoid the use of cutting fluid in machining operations. Some of these alternatives are dry machining and machining with minimum quantity lubrication (MQL).Dry machining is now of great interest and actually, they meet with success in the field of environmentally friendly manufacturing . In reality, however, they are sometimes less effective when higher machining efficiency, better surface finish quality and severe cutting conditions are required. For these situations, semi-dry operations utilizing very small amount of cutting fluids are expected to become a powerful tool and, in fact, they already play a significant role in a number of practical applications . minimum quantity lubrication (MQL) refers to the use...
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