Mould Filling Ability Characterisation of Cast Aluminium Alloys Using Design of Experiments

Mould filling ability characteristic has been influencing the liquid metal flow, heat transfer, and solidification there by affecting the quality of aerospace castings. Mould filling is a critical parameter in the production of sound and quality castings, especially in the case of complex-shaped castings where section thickness is varying considerably. The mould filling ability of aluminium alloys LM6 and LM25 has been studied in the present investigation. Experimentation has been carried out using orthogonal array experimental layout. The process parameters studied in the present investigation are alloy composition, sand fineness, mould coating, and pouring temperature. The mould filling ability of selected aluminium alloy has been studied using pin test piece with cylindrical cores. The results from experimentation are analyzed to find the influence of the process parameters on mould filling ability. Based on the above, LM6 alloy has been found to have better mould filling ability characteristics and the analysis of variance has also revealed the same optimum factor combination. 1. Introduction Metal casting is unique among metal forming processes for a variety of reasons [1]. Aluminum castings have played an integral role in the growth of the aluminum industry since its inception in the late 19th century. Popular aluminum casting alloys contain, in addition to strengthening elements, sufficient amounts of eutectic-forming elements (usually silicon) in order to have adequate fluidity to make the metal flow through the cavities. The aluminum castings and applications rapidly expanded to address the requirements of a wide range of engineering specifications and continuing market requirement to reduce vehicle weight and to increase fuel efficiency. Complicated physics involved in the casting process is fluid mechanics with phase change, shrinkage, porosity, macrosegregation in alloys, heat transfer between metal and mould, and thermal stress in the solidifying ingot [2]. Thin-wall aluminium alloy casting techniques can be used to produce clean castings of lower weight and with superior mechanical and physical properties compared to those produced by more complex traditional methods and are ideal for automotive applications [3]. The filling of the mould is an essential part of the entire casting cycle. Mould-filling ability is the bottleneck of manufacturing thin-walled castings [4]. The solidification of the melt during the mould filling continuously changes the properties of liquid and solid phases. The filling conditions play a significant role on the