THIXOMOULDING INJECTION MOULDING OF SEMI-SOLID MAGNESIUM ALLOYS

Abstract

The thixomoulding technology, i.e. the injection moulding of thixotropic, semi-solid magnesium, represents a new, innovative and fully automated processing technique for magnesium alloys, which combines substantial processing elements of the magnesium die casting and the conventional plastics injection moulding. The process technology is very similar to the injection moulding of thermoplastics, except magnesium is being moulded. The two objectives pursued by thixomoulding are the process substitution of die casting of certain component parts on the one hand and the material substitution in special fields of plastics injection moulding on the other hand. Magnesium offers a considerable potential for material and structural lightweight construction. Thus, by means of the thixomoulding technology, a multitude of lightweight and mechanically high-grade net or near net shape parts can be manufactured, requiring no or very little finishing. Thixomoulded parts can be found in the areas of consumer electronics (for example housings for cell phones, laptops, cameras etc.) and in the fields of the automotive industry (in the form of thin-walled structural components). The thixomoulding process is environmentally friendly, since small amounts of argon can be used for an inert gas atmosphere in the mostly encapsulated plasticising unit, instead of ozone depleting gases, such as SF 6 , generally used in die-casting. At the same time, the process is operator friendly as well, since the danger of exposure to molten magnesium is minimised due to the closed machine.