PERMANENT MOULD DESIGN, CASTING AND ANALYSIS OF ALUMINUM PISTON FOR 950 WATTS GENERATOR

Abstract

There is a high demand for imported generators due to irregular power supply in Nigeria. This has increased the need for generators’ spare parts especially, piston which soon gets worn out after a reasonable service life. Aluminium is the ideal material for producing internal combustion engine components because of its high strength to weight ratio, good formability, good resistance to corrosion and recycling potential. Aluminium-silicon alloy pistons for 950 Watts generators were cast using old 950 Watts generators pistons’ scraps as charge materials. The casting was carried out using permanent mould (gravity die-casting) technique. A permanent mould was designed for casting the piston. In the numerical experiment for heat transfer, the external surface temperature of the simulated mould rose to about 630 ℃ after 60 s of pouring the molten alloy into the mould. This implied that the mild steel material selected for the mould permitted good thermal dissipation from the molten metal to the mould. The piston core also facilitated heat transfer from the molten metal to the core as the time increased from 0 s to 10.5 s. The surface area of the piston core received the maximum thermal energy (temperature) when the molten Al-Si alloy was poured into the mould at about 1 s. The microstructure analysis carried out on test samples showed sufficiently homogeneous grain distributions with dendrites within the matrices of the as-cast piston. The results of the chemical composition showed that the cast aluminum alloy was a hyper eutectic Al-Si (with 13% Si) alloy. The mechanical properties of the cast pistons were determined by carrying out tensile and hardness tests on the cast specimen. Maximum average ultimate tensile stress and Brinell hardness of 168.44 N/mm2 and 111 BHN were obtained respectively. These results closely aligned with the literature values for LM13 alloy