Sharif Digital Repository

Thermal expansion and hot deformation are two phenomena causing dimensional errors in investment casting. This error occurs in dimensions between the die and wax pattern. Therefore, the wax's thermo-physical and thermo-mechanical properties, the metal die features, and the process parameters affect the dimensions of the wax pattern. Some important effective process parameters are the injection temperature, die temperature, and holding time. In this paper, the effect of injection parameters on the dimensional accuracy of the wax model created by a metallic die is studied. The Taguchi formulation based on the design of experiments is applied to obtain the optimum condition in achieving the... 

In this work, cristobalite crystallization and its effects on mechanical and chemical behaviour of injection moulded silica-based ceramic cores were investigated. In order to simulate casting process condition, the sintered samples at 1220 °C were also heated up to 1430 °C. Flexural strength test was carried out on both sintered and heat treated samples. Chemical resistance of the cores was evaluated by leaching the samples inside 43. wt% KOH solution at its boiling point. Phase evolution and microstructure were investigated by thermal analyses (DTA and DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM). Results showed that cristobalite was... 

Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance... 

A rapid wax injection tool of a gearbox shift fork was designed, simulated, and manufactured using rapid prototyping and rapid tooling technology to save time and cost of producing wax models used for the investment casting process. CAE simulation softwares, in particular, MoldFlow, are used to get wax injection moulding parameters such as filling parameters, temperature profiles, freeze time, speed, and pressure. The results of this research were compared with conventional wax model production methods. The criteria of such comparison were based upon parameters such as time, cost, and other related characteristics, which resulted in saving of 50% in time and 60% in cost. In this research,...