بررسی ادبیات روش ها برای مطالعه و طراحی سیستم دروازه برای اثر آن بر کیفیت ریخته گری

For the optimum design of gating system, the study of filling process is of great significance since it directly affects casting quality. The goal of proper mould filing cannot be achieved without proper gating design which influences the flow pattern, further affects the temperature distribution and modifies the progression of solidification. But it is not only expensive but difficult to observe the molten metal flow in the mould directly due to the opacity of sand mould.For the study and analysis of flow of molten metal through the gating system and into the mould cavity, many researchers have tried various techniques which can be broadly classified as direct observation method and through modelling the process by water analogy or by computational modelling.To get accurate and dependable prediction of the subtle transient events, one has to make a judicious combination of both methods for casting with an alloy system. Many researchers attempted to use numerical simulation techniques to analyse the molten flow through the gating system, which has an advantage to accurately predict subtle transient events and gain more profound information about the behaviour of metal stream. Considerable materials are available in literature to understand the influence of gating system design on mould filling using various techniques of direct observation validating the given design of gating system by using real time X-ray radiography to observe the flow of molten metal in a sand mould, or by using contact wire sensing method along with computerized data acquisition, or by using water analogy method to observe the flow of water in a transparent mould.Also few researchers attempted optimization of gating system in casting to control defects and maximize the effective yield of the cast products. This paper comprehensively review the available literature for various techniques to study, analyse and predict the flow behaviour of the melt in order to minimize the related defects arising due to melt flow and also increasing the effective yield of the casting with minimum effect on its quality.