Casting container
The casting container is part of a hot chamber die casting machine .
The working temperature for magnesium alloys is relatively high at 620 - 640 ° C, while it is around 390 - 420 ° C for zinc alloys . The casting containers are made of hot-work steel in forged and cast versions. The forged casting containers have a higher homogeneity in the material , while the cast ones are less prone to stress cracks due to their uniform wall thickness transitions .
In the case of zinc, the entire casting set consists of the casting container with built-in compression chamber, compression piston with piston rings and nozzle. With magnesium there is no built-in pressing chamber. The casting container is replaceable as a wear part. In the case of zinc casting containers, the press chamber is replaced when the wear limit is reached; for magnesium, the hole in the casting container is increased to the next possible level. The nozzle is inclined by 5 degrees in relation to the machine. When the die- casting mold is open, the molten metal flows out of the nozzle back into the casting container and no drops form in the mold.
If the nozzle is constantly in contact with the mold, precise control of the nozzle temperature is necessary. It is important to ensure that the contact surface of the nozzle on the mold is as small as possible in order not to conduct the heat into the mold. The nozzle can be moved to the mold half by hydraulic cylinders (also called approach or tear-off cylinders). In the case of zinc, the nozzle is heated electrically with an insulated nozzle, and in the case of magnesium, either by gas heating , induction heating or electrical resistance heating. Exact temperature control is almost impossible with gas heating.