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Polishing is considered as the last and most important step in the manufacturing of optical component. Computer control polishing (CCP) methods are usually used to polish complex surfaces. In this method, material removal is controlled at each point, depending on error at that point. In contact polishing mechanism, tool feed rate is often controlled to eliminate local errors. It means that the higher tool feed rate, the lower material removal would be and vice versa. Tool influence function (TIF) which is defined as the instantaneous material removal under the polishing tool for a given tool motion, is the most important parameter in CCP and its predictability during the polishing process leads to reliable result. In this study, a new spherical tool which can polish complex surfaces by using a 3- axis CNC machine is presented. Because of spherical geometry of both tool and workpiece, tool material removal rate is variable because of changing the angle between tool axis and surface normal vector that leads to variation of relative speed. Tool influence function which depends on tool engagement’s angle was modeled based on Pereston equation. Moreover, the simulation is modeled based on discretization of tool path. To evaluate the methodology, some polishing experimental testes were performed. The experimental results show that a 130 mm spherical convex lens with initial surface roughness of 1.114 micrometer for PV was decreased to 395 nm for PV using the CCP method developed in this study.

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Selecting tool materials, tool sizes and determining the cutting parameters presents a great challenge in machining operations especially in high speed machining processes. In this study effect of feed rate which is one of the important machining parameters and tool size on tool life in high speed machining of Ti-6Al-4V alloy were investigated. Fixed cutting speed of 200 m/min, feed rate of 0.03 and 0.06 mm/tooth together with axial cutting depth of cut 5.0 mm, and radial cutting depth of cut 1.5 mm were employed as the cutting parameters. TiAlN + TiN coated tungsten cemented carbide insert in two different size was used during machining operations. Flank wear land measurement was taken by using a toolmakers’ microscope and recorded accordingly throughout machining processes. The results showed during the machining employing both feed rate and using smaller tool size chipping occurred on the tool nose along with gradual tool flank wear. Also by increasing the feed rates utilizing the smaller size of tool highly affected tool life compared to employing the larger one during the high speed machining operations. Reduction the feed rate by 50 percent increased the tool life of smaller tool size by 200 percent.

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Machining of hard steels has it’s own problems. According to the recent advances in implementing of new cutting tools, the machining of hard steels with operations such as turning and milling is possible and it can replaced with some of grinding operations. Turning of workpieces with 45 HRC or upper hardness, is said hard turning. The aim of this article is the investigation of the effect of workpiece hardness and cutting speed and feed rate parameters on surface roughness in hard turning of cold work tool steel X210Cr12 or SPK in dry condition. For achieving this goal, the workpieces of X210Cr12 steel where hardened with different heat treatments cycles such that their hardnesses lie in the hard turning range. Then the workpieces were machined with different cutting parameters using CBN tool and the resulted surface roughness were compared. Experimental tests designed with full factorial method and totally 36 tests have been done. According to obtained results of experimental tests and analysis of variance, the effect of feed rate and workpiece hardness on surface roughness was 90.4% and 8.3%, respectively. The effect of cutting speed on surface roughness is negligible. Increasing the feed rate results in the upper surface roughness. Increasing the workpieces hardness to 50 HRC, decreases surface roughness and increasing workpieces hardness from 50 to 65 HRC, increased surface roughness.

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Composites reinforced with carbon fibers have various applications in different industries, due to their physical and mechanical properties. In this regard, multi-walled carbon nanotubes are used to strengthen the epoxy resin base, which is one of the emerging and important materials. Since machining is required to repair reinforced composite parts, in this research, the damages caused during the process should also be investigated and solutions should be provided. In this study, the delamination damage in the machining of composite parts of epoxy reinforced with carbon fibers and multi-walled carbon nanotubes has been discussed. In this regard, experiments have been conducted with a carbide end-mill at different cutting speeds and feed speeds. Then the delaminations created in these tests are studied. In the analysis of the results, by increasing the rotational speed from 500 to 2500, the amount of delamination increased by 25% and the force decreased by 87%. Also, solutions that include reducing the feed speed will have a significant effect on improving the final quality of the machined part.

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In this article, the effects of changing four different input parameters such as cutting speed, feed rate, feed force in Z direction and force in Y direction on the output of tool wear in the machining process of aluminum metal base composite have been investigated. To numerically examine the influence of each parameter on the  desired composite machining process results, the E-fast sensitivity analysis procedure was used. E-fast method has a high speed in quantitative and qualitative data analysis. After conducting a sensitivity analysis, it was found that as the feed force increases in the X direction, the  tool wear increases with a significant slope. It was also observed that this parameter (feed force in  X direction) has the greatest impact on  tool wear compared to other input parameters with an amount of 88%. The parameters of feed rate, feed force in Z direction and cutting speed are effective on tool wear with negligible rates of 8%, 3% and 1%, respectively.