Table of Contents

The process

The hot chamber die casting technique is mainly used for metals such as magnesium, zinc, and other low melting alloys.

Compared to the cold chamber die casting process, in this method, the machine itself contains the melting pot, which makes it easier and more efficient.

Source: Open University

The other advantage of the hot chamber process includes long die life and reduced porosity using the alloys, which do not damage or erode the machines when subjected to high temperature and pressure.

Superior quality castings can be manufactured using this process due to the optimal control of molten metal flow to the die.

The furnace is attached to the die casting machine utilizing a metal feed system, most commonly known as a gooseneck. The injection mechanism is immersed within the molten metal.

The power for the injection strokes is provided by the short cylinder located above the molten metal supply.

The plunger rod moves down from the short cylinder to the plunger in contact with the molten metal.

In the starting cycle of casting, the plunger is at the top of the chamber. The molten metal fills the chamber through the intake port.

Once the process begins, the plunger is pushed downwards. The plunger moves downward past the intake ports cutting off the molten metal’s flow to the hot chamber.

Now the chamber has the exact amount of liquid metal that is required to produce the casting. The plunger travels further downwards, forcing the metal within the chamber to the die.

The pressure is held for enough time to solidify the casting. In typical cases, the pressure exerted on the molten metal to manufacture the casting varies from 700psi to 5000psi.

This completes one full cycle of casting.

To prepare for the next cycle of production, the plunger travels in the opposite direction in the hot chamber, opening up the intake ports once again.

Once the intake ports are opened, liquid metal flows into the hot chamber.

Advantages of hot chamber die casting

Hot chamber die casting process’s main advantage is the fast cycle time and the ease of melting the metal directly within the machine.

Reduced porosity
Faster cycling production
Longer life of the machinery (since metals with low melting points are only handled)
More efficient process
Lesser metal wastage

Disadvantages of hot-chamber die casting

The main drawback of a high pressure die casting process is porosity. However, this can be reduced by using an evacuated chamber with specialized application techniques.

Since pores are present on the surface, the die casting cannot be fully heat treated as it will lead to the formation of blisters on the metal’s surface.

Another disadvantage is the high initial start-up cost required for setting up the die-casting equipment.