Abstract:Controlling process parameters of lost foam casting (LFC) enables this process to produce defect-free complex shape castings. An experimental investigation on lost foam casting of an Al-Si-Cu cast alloy was carried out. The effects of pouring temperature, slurry viscosity, vibration time and sand size on surface finish, shrinkage porosity and eutectic silicon spacing of thin-wall casting were investigated. A full two-level factorial design of experimental technique was used to identify the significant manufacturing factors affecting the properties of casting. Pouring temperature was found as the most significant factor affecting Al-Si-Cu lost foam casting quality. It was shown that flask vibration time interacted with pouring temperature influenced eutectic silicon spacing and porosity percentage significantly. The results also revealed that the surface quality of the samples cast in fine sand moulds at higher pouring temperatures was almost unchanged, while those cast in coarse sand moulds possessed lower surface qualities. Furthermore, variation in slurry viscosity showed no significant effect on the evaluated properties compared to other parameters.

Key words: Al-Si-Cu alloy; lost foam casting; full factorial design; surface finish; porosity; silicon spacing