• MEHDI SAFARI

      Articles written in Sadhana

    • Process parameters selection in manufacturing of sharp conical parts based on Taguchi design of experiments

      MEHDI SAFARI JALAL JOUDAKI

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      Among the sheet metal forming processes, hydrodynamics deep drawing and hydromechanical deep drawing process are two main types of the deep drawing process that can fabricate complicated parts. In the hydroforming process, the blank is formed to the desired shape by applying a considerably high hydraulicpressure. In this article, the selection of the process parameters will be investigated during the manufacturing of a pure copper sharp conical part by finite element analysis and experimental tests. Two finite element models aredeveloped for hydrodynamics deep drawing and hydromechanical deep drawing processes. After verification of the FE model by experimental results, the effect of process parameters includes the applied pressure, friction coefficient, die radius and blank holder force on thinning of the blank are investigated. The thinning ratio of blank is calculated in different zones of the conical part under different working conditions determined according to the Taguchi design of experiment methods. Signal to noise ratio analysis has been carried out and the influence of process parameters on the thinning ratio is determined at different zones of the conical part. The results show that the friction coefficient has an important role in the thinning of the conical nose while at the lateral surface of the cone, the die radius is the most effective parameter on the thinning ratio. The results showthat by implementing statistical tools (Taguchi method and signal to noise ratio analysis), it is possible to select the proper process parameters conditions and fabricate defect-free parts. In addition, a non-linear regression equation is developed for prediction of thinning ratio in the hydrodynamics deep drawing and hydromechanical deep drawing processes.

    • Experimental investigation of laser cladding of H13 hot work steel by Stellite 6 powderandiaoy

      MEHDI SAFARI MAHMOUD MORADI JALAL JOUDAKI AMIR MOHAMMAD BABAEI

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      Cladding of metals can enhance the wear behavior of metals. Many dies work at elevated temperature such as hot forging dies and hot extrusion dies need resistance to wear at higher temperatures. In this article, the cladding of H13 hot work steel (DIN 1.2324) was investigated by laser cladding. The Stellite 6powders coat the steel surface by using a continuous fiber laser. Two important objects in cladding are the effect of laser process parameters on the quality of the cladding layer and the lateral overlapping percent in adjacent passes. The laser power, scanning speed, and powder feed rate are the process variables in the study. The results show that the laser power is the most influencing parameter and by increasing laser power and decreasing the scanning speed, the hardness and penetration depth of cladded powder in the substrate will be increased. The dilution factor increases by increasing the laser power and reducing scanning speed at a moderate powder feed rate. The microstructure observation shows that strong metallurgical bonding between the clad and substrate and good mixing of powder in substrate metal can be obtained by proper setting of process parameters. The microhardness of the cladded specimen increased to 300 HV (164% increase compared to the substrate material. Best results were obtained at 10% overlapping between adjacent irradiation passes.

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