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In this research, the machinability of iron-recycled grey cast iron powder metallurgy parts is investigated. For this purpose, grey cast iron swarfs were transformed to powders by target jet milling method and were then used to prepare powder metallurgy parts in combination with commercial iron powder. Green compacts were prepared with the variables of cast iron powder percentage and compaction pressure. Design of experiments was conducted by response surface method for sintered parts with the variables of cast iron powder percentage, compaction pressure, sintering temperature and sintering time each in five levels. Regression analysis and analysis of variance were used to investigate the effect of input parameters, develop the mathematical models and evaluate the validity of the models. In the green section, machinability was qualitatively investigated in drilling. For sintered parts, machinability was evaluated by measuring the thrust and torque forces and the obtained surface finish in drilling. The obtained results certificated the accuracy of the extracted regression equations for predicting the machining properties of the parts. Also, the results demonstrated that the addition of jet milled grey cast iron improves the machinability of iron-based powder metallurgy parts.

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Nowadays, laser 3D printers are one of the efficient devices for rapid prototyping process. There is vast number of studies about quality of samples in these printers. The laser sintering technique is the one of the popular method for consolidation and shaping of semi-crystalline polymer powders. In this study, we considered the role of laser parameters included laser scanning pattern, laser scanning speed and power in tensile strength and stiffness as the important factors of the mechanical property of samples which are sintered by laser in single layer procedure. Experimental samples were sintered with low power CO2 laser on Polypropylene powder with 200 micrometer grain size. Tensile strength and stiffness had been measured according to ASTM D882 standard and results were reported eventually. In this paper, main effects of factors and interactions were considered via the variance analysis under the imperative conditions that have been passed before. The regression equation was derived finally. A general full factorial method was employed as experimental design. The results show that the laser scanning pattern and laser power have most effects on tensile strength and stiffness of produced samples. The maximum value of responses, 2/9 MPa for mechanical strength and 96 N/mm for stiffness, demonstrate that the 2W power of laser with 1650mm/min of scan speed can be the proper value to obtain an optimal response when the selected pattern is No2.

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Additive Manufacturing (AM) or 3D printing is a method to build parts by adding layer-upon-layer of material. The selective laser sintering (SLS) method is one of the most important methods of additive manufacturing processes. The low time and the variety of materials used to build the parts are major advantages of SLS method. The high quality of the product is one of the main goals in the additive manufacturing processes. The part warping is one of the factors that reduce the quality of the products which are built by the SLS process. The hatching patterns and scan algorithms in the SLS process are important factors that affect the product quality. In this paper, the effective parameters of the SLS processes such as the scan vector length and the number of offsets or contours, the laser power, the laser speed, and the hitching spacing are optimally determined to minimize the part warping of the product based on the finite element simulations and Taguchi method. For this reason, SLS process has been modeled on the SLS process. Then, to illustrate and validate the accuracy and efficiency of the proposed method, and the computational results are compared to the obtained results from the experimental tests Using SLS containing CO2 laser. Finally, using the Taguchi design of Experiments, the process parameters have been changed at different levels and optimal parameters have been obtained.

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Additive manufacturing or 3D printing processes through which applicable complicated parts are directly made based on 3D model of the part has been extensively addressed in numerous research and development tasks for the past years. Certain merits such as decline of time, cost of design and manufacturing of product, processing different engineering materials, manufacturing parts with highly complicated geometries, and manufacturing customized parts should be noted in the case of adopting these methods. Indirect selective laser sintering is one of the interesting methods of integrated manufacturing which could be used for manufacturing of complicated pieces and certain materials such as ceramics with a high melting point and difficult manufacturing process through typical methods. In the present study, indirect SLS of spherical alumina powder particles with a thin layer of amorphous thermoplastic (PMMA and PS). In order to coat alumina particles with different weight percent of thermoplastic, the new method of phase Inversion process was used. Due to significance of geometry and dimensions of the final part, the least probable thickness of thermoplastic was used for manufacturing of parts based on SLS method. In the present study, evaluation of coating and method of coating have been discussed. The evaluative techniques include assessment through scanning electron microscopy, analytical results of Fourier transform infrared spectroscopy and thermogravimetric analysis and differential scanning calorimetry. Finally, green parts where produced based SLS method and through optimal values of laser parameters and selection of alumina powder particles with thinnest thermoplastic coating.

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With the development of additive manufacturing technology, the quantity of devices that can be used in small office with the commercial or educational purposes increases. In this research, the goal is to build a desktop 3D printer with selective laser sintering technology, which can be used for research purposes. The main concentration is focused on fabrication with parts that can be manufactured in the country or can be procured from the domestic market. It is also tried to make the 3D printer compatible with the common open-source additive manufacturing softwares. The fabricated 3D printer has the ability to work with all kinds of common polymer powders. In addition, it is easy to update the device's firmware according to the researcher's needs. The capabilities of the device was tested with Glucose powder, paraffin wax powder, and thermoplastic-ceramic material combinations. It is currently used for research on fabricating ceramic parts with indirect laser sintering.