In this paper, an experimental investigation on shape replication and surface roughness of Al-12 wt% Si alloy casting produced by lost foam casting process was conducted. 5-step shape patterns incorporated with top and bottom gates were used. Four top gating systems with different pouring cup configurations namely single-middle, single-side, double and single-wide and a simple bottom gate design were investigated to appropriate filling to produces sound casting. Three sand vibration times of 1, 2 and 3 min were used for the moulding process. Molten metal was poured at five different temperatures of 660, 680, 700, 720 and 740°C. Shape replication and surface roughness of the cast samples were analysed visually and by roughness tester, respectively. The results showed that pouring cup design has a significant effect on the replication and surface integrity of the castings. It was also found that single topwide pouring cup as well as lower vibration time and higher pouring temperature provided castings with better shape replication and smoother surface finish with a surface roughness of 19-20 lm compared to 25-31 lm for castings produced with other cup configurations.
This paper presents the experimental investigation conducted on Al-Si cast alloy (LM6) cast using lost foam process. The main objective of the research is to investigate the effect of pouring temperature, section thickness and melt treatment on the microstructure of the lost foam casting of Al-Si alloy. Step pattern with five different sections was prepared from 20 kg/m³ density foam and poured at five different temperatures; 700, 720, 740, 760, and 780 with and without the addition of AlTiB as grain refiner. Analysis on microstructure, eutectic silicon spacing and porosity percentage were conducted to determine the effect of both parameters. The results show that pouring temperature has significant influence on the quality as well as microstructure of the lost foam casting of LM6 Al-Si alloy. Lower pouring temperature was found to produce finer microstructure casting. However, the addition of AlTiB as grain refiner did not affect the produced castings significantly whether in terms casting quality or microstructure.
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