Effect of Rotation Speed at Vertical Centrifugal Casting Process Study to Hardness and Microstructure Alsi Alloy

Metal casting is one of metal forming process that can create complex shape. To make object with cylindrical structure it is easier to apply centrifugal casting method. Centrifugal castings are suitable for pulley manufacturing because they can produce gradations properties. This study examines the effect of rotational speed on density, microstructure and hardness at centrifugal casting process. This study use remelting piston that remelted to AlSi alloy and run into spectro test. The casting process is carried out at temperature of 750–800 °C while the mold preheated by acetylene welding up to 500 °C. Molten metal poured at 750 °C at the mold then the mold was rotated for 3 min. Casting object have cylindrical shape with 130 mm diameter and 35 mm height. Result of properties test are the lowest hardness value at 400 RPM (74.55 BHN) with 1.8% porosity. While the highest hardness value at 1000 RPM (76.8 BHN) with 2.24% porosity.