Casting machines and properties of Al-Si castings alloys

The paper focuses on the research of holding pressure inside the mould cavity and pressing speed as technological parameters of die casting. The experiments conducted within the frame of the practical part examined the plunger and the pressure or the holding pressure in the mould cavity influencing the mechanical properties of a casting which were represented by ultimate tensile strength and percentage share of porosity of Al-Si castings. The results of experiments and analysis of the measured values proved the relation between pressure, or holding pressure, in the mould cavity and the ultimate tensile strength and porosity of castings. Plunger pressing speed is closely related to mould cavity filling mode which affected the final porosity of casting. It can be assumed that die casting is positively influenced by the increase of ultimate tensile strength and reduction of porosity during the increase of pressure or of holding pressure in the mould cavity. Higher values of holding pressure caused the elimination of pores which resulted in a decrease in the percentage share of pores in the casting and an increase in values of ultimate tensile strength.