Mechanical Properties of Cast Aluminium Rods under Varied Oundry Sand Sizes and Mould Preheat Temperatures

The impacts of foundry sand sizes and mould preheat temperatures of range 30-200 C on the mechanical properties of cast aluminium rods were experimentally investigated and presented. At the same mould preheat temperature, cast specimens from fine sand mould exhibited highest tensile, impact and torsional properties with better hardness values. Also, preheating as-prepared fine sand mould to isothermal temperatures of 100 and 200 C for 1 h caused the percentage elongation of its cast specimen to increase from 9.8-11.8 and 13.5, respectively impact energy increased by 13.3 and 33.3%, respectively from initial value of 15 J, while its hardness, tensile strength and ultimate shear strength having respective initial values of 61.8 HRB, 144.6 MPa and 2.050 GPa correspondingly decreased by 11.5, 13.0 and 9.76% due to mould preheat to 200 C. Hence, for optimal mechanical properties, fine sand is found appropriate and preheating sand mould to about 200 C for some period in the furnace is considered adequate in effecting small changes in the mechanical properties of cast specimens, while avoiding crack formation in the sand mould due to excessive heat accumulation.