The method of cold chamber die casting is mostly preferred for metals that have very high melting points. This includes metals such as copper, brass, and aluminum.
As the furnace is not attached to the machine, it will require an outside furnace and a ladle to pour the molten metal.
The cold chamber die-casting process is quite known for its ability to produce denser metal casings.
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The process
In this process, the metal is heated to a molten state in a furnace located outside the machine.
The liquid metal is then transported to the casting machine and fed into the machine’s chamber.
Source: Learn Mechanical
The machine uses a plunger, which forces the liquid metal into the cavity of the mold.
The pressure usually ranges from 2,000 and 20,000 psi.
The separate heating process differentiates the cold chamber die casting process from the hot chamber one.
The molten metal is transferred either manually or automatically by the ladle to the shot sleeve. The injection piston forces metal into the die.
As this is a single-shot operation, this process helps minimize contact between the injector components and hot metal. This helps to further enhance the operating life and efficiency of the machine components.
With this process, it is possible to lower the melting point of alloys.
The process of cold chamber die casting is ideal for metals with corrosive properties or high melting points.
Advantages of Cold Chamber Die Casting
1. Long-lasting and robust components
Cold chamber die casting helps to create parts that are strong and long-lasting. The components manufactured out of this process are robust and improve the visual appeal of the surrounding area.
2. Cost-effective process
This process is highly effective and saves many costs, helping to create a broad range of components compared to other manufacturing methods.
3. Increased strength
Cold chamber die casting helps to create stronger parts than those made out of plastic injection moldings having the exact dimensions.
4. Easy to assemble
This process helps to create fastening elements such as studs and bosses. Holes can be carved, and external threads can be cast.
5. Accurate in dimension
Using this process, machine parts can be created: heat resistant, dimensionally stable, and having a high level of tolerance.
6. Better finished products
The process of cold chamber die casting helps to produce smooth parts having a high level of finish. The products can easily be plated and finished by menial effort.
Difference between the Cold Chamber and Hot Chamber process
The primary difference between a cold chamber and hot chamber die casting is that in the latter, the source of molten metal is attached to the machine in a hot chamber process. In contrast, in a cold chamber die casting process, liquid metal is introduced into the chamber from an external source.
In the cold chamber process, as the molten metal is brought from an external source, the die casting machinery will stay cooler and handle metals with a high melting point.
Industrial manufacturing of metals with a high melting point such as zinc, aluminum, brass, and copper is usually done with a cold chamber die casting process.
One slight disadvantage of the cold chamber process is that the manufacturing process is a bit slow compared to the others as the material must be brought in for every production cycle.
On the other hand, in a hot chamber manufacturing process, there will be a constant output.
The cold chamber process requires more pressure than that of the hot process. For the cold die casting, pressures of 3000psi to 50000psi (20MPa to 350MPa) are needed to fill the cold chamber with the molten metal in the right amount.
The cold chamber process creates better castings with superior mechanical properties. The castings that are produced have a smooth finish with thin falls.
The article is a part of our comprehensive series on “Die casting: Process, Equipment, Uses, and More”.
