This project is to produce tertiary alloy of Zinc-Aluminium-Magnesium (Zn-3Al-2Mg) with different composition of bentonite and silica sand in the green sand mould. Zn alloy casting industry using green sand molding is increasingly becoming to very competitive circumstance, due to the various casting methods such as die cast, sand mould and so on with the recent coming of the lightening demand in automotive and decorative industry. However, Zn alloy casting using green sand still now plays an important role in the foundry society, because it allows us to manufacture at low cost and also sand can be recycled. Furthermore, it is appropriate method for multi kind and small quantity production. The mentioned method of mold is differing in composition of bentonite with 5%-17%. Differ in the composition of bentonite and silica sand give differ in result. The properties are obtains from the surface, the hardness test, the tensile test and the microstructure. Lowest and highest percentage of bentonite gives a dull surface properties compare to the in between. The shiniest surface is from the 15% of bentonite. Meanwhile, for the hardness test and the tensile strength, the results show the same with the surface properties. The morphologies give not much difference from each other.
