PRESSURE DIE CASTING
The pressure die casting is the most economic casting method for the production of very high quantities due to the fact that the same mould is used again and again and the casting goes very quickly.
The metallurgical influence on the alloy is only very slightly owing to this high solidification speed. Thus, in general the grain refining and modification of the melt is not necessary.
However, the possibility of heat treatment to increase the mechanical values and the weldability is expected. Due to the high solidification speed hydrogen can be deposited in a supersaturated state, which accumulates at the oxides and forms pores after the heat treatment.
As a consequence of this a thorough cleaning is imperative. This applies above all to parts which are anodised, chromium-plated, welded or heat treated. If hypereutectic alloys are used a refinement of the silicon can contribute to an increase in strength.
A thorough treatment of the dross to reduce the proportion of metal is imperative due to the high quantity of non-metallic impurities the returns in the pressure die casting contain.
The melt treatment of the alloys used in the pressure die casting is carried out for:
Cleaning of non-metallic impurities and inclusions
Treatment of the dross to reduce the proportion of metal in the dross and to avoid the formation of build-ups on furnace walls.
Refining of the silicon in hypereutectic alloys in order to increase the mechanical values.