This paper demonstrates the effects of multilayer coatings on the thermal conductivity of tool specimens. The experiments were conducted using copper specimens and four tool specimens with different coatings (uncoated, TiN, TiN/TiCN, and TiN/Al2O3/TiCN). An electrical furnace technique was used with the specimens isolated from their surroundings and temperatures measured at the contact surfaces. The specimens are joined securely, with a thermal insulator (glass wool) placed around them so that the heat flow is in the axial direction only. One surface of the copper specimen faces the heat source, and the opposite end of the tool specimen is exposed to room temperature. The experimental results displayed variations in the temperature distribution due to the effect of the coatings, and thermal conductivities were measured at temperatures ranging from 100°C to 300°C. The results indicated the optimum coating for tools (lowest thermal conductivity) of the four types is TiN/Al2O3/TiCN.
Electric discharge machining(EDM) is one of the nonconventional machining process which has been used in manufacturing complex shapes on hard material that are difficult to cut by conventional processes, especially, die casting, parts of aircraft, medical equipment, automobile industries. Powder mixed electric discharge machining (PMEDM), has emerged as one of the advanced techniques in the direction of the enhancement of the capabilities of EDM. The objective of the present research is to study the influence of process parameters such as peak current, pulse on time, manganese, aluminum, and aluminum-manganese mixing powder concentration on machining performance of different types of die steel (AISID3, AISID6, H13) with round copper electrode(20 mm diameter) on machining performance. Experiments have been designed using Taguchi method. Taguchi L27 orthogonal array has been selected for five factors 3 levels design. The machining performance has evaluated in terms of metal removal rate (MRR). It is found that manganese powder concentration mixed in dielectric fluid significantly affect the machining performance, maximum (MRR) is obtained at a high peak current (12 A), pulse on (200µs), and (4g/L) concentration of manganese powder, the optimum MRR is 17. 56mm 3 /min with percent of error about 5.61% compared with the Experimental value.
RS (residual stresses) represent the main role in the performance of structures and machined parts. The main objective of this paper is to investigate the effect of feed rate with constant cutting speed and depth of cut on residual stresses in orthogonal cutting, using Tungsten carbide cutting tools when machining AISI 316 in turning operation. AISI 316 stainless steel was selected in experiments since it is used in many important industries such as chemical, petrochemical industries, power generation, electrical engineering, food and beverage industry. Four feed rates were selected (0.228, 0.16, 0.08 and 0.065) mm/rev when cutting speed is constant 71 mm/min and depth of cutting 2 mm. The experimental results of residual stresses were (-15.75, 12.84, 64.9, 37.74) MPa and the numerical results of residual stresses were (-15, 12, 59, and 37) MPa. The best value of residual stresses is (-15.75 and -15) MPa when it is in a compressive way. The results showed that the percentage error between numerical by using (ABAQUS/ CAE ver. 2017) and experimental work measured by X-ray diffraction is range (2-15) %.
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