Cold Chamber Die Casting is a manufacturing process for metals with a high melting temperature. It is one of the two primary die casting processes with the other being Hot Chamber Die Casting.
The process is carried out in a Cold Chamber Die Casting Machine where the metal is molten in a container separate from the machine. Since the die casting machine itself remains cool, the process came to be known as Cold Chamber Die Casting.
Cold Chamber Die Casting is a discrete process that is carried out after pouring metal into the shot chamber from an external source. The process of cold-chamber die casting is explained below:
The metal to be cast is melted inside a separate container
A specified amount of Molten metal is carried with a ladle and poured into the shot chamber connected to the die cavity
The molten metal is pushed into the die cavity under high pressure exerted by a plunger
The molten metal will spread throughout the cavity and take shape
Then it is left for solidification and cooling
The moving half of the die is then ejected and the casting is collected from it
Then the dies are clamped again to proceed for the next casting cycle in a similar manner
COLD CHAMBER DIE CASTING ADVANTAGES
Cold Chamber Die Casting lacks some of the benefits of Hot Chamber Die Casting. But it makes die casting some convenient metals possible. The biggest advantage is that It made casting metals with a high melting point such as Aluminum possible. Aluminum is the best die casting metal considering both cost and strength. So you will need Cold Chamber Die Casting if you decide to go for Aluminum Die Casting.
Normally High-temperature metals can damage the die casting machine. This was a big concern for die casting manufacturers. Cold Chamber Die Casting made handling high-temperature metals easier.
Cold Chamber Die Casting requires the application of high pressure. That can produce denser parts with better mechanical properties. Higher pressure also enables your parts to maintain thin walls and provide intricate details.
The maintenance cost is Cold Chamber Die Casting is quite reasonable as well. This will especially help you bring down the overall production of Aluminum Die Casting which is already pretty cost-effective.
COLD CHAMBER DIE CASTING MACHINE COMPONENTS
A Cold Chamber Die Casting Machine consists of the following components:
Moving Die Half
Fixed Die Half
Cold Chamber/Shot Chamber
Hydraulic Piston (Plunger)
Most of the components of a Cold Chamber Die Casting system is identical to that of a Hot Chamber. Some changes are made to incorporate the metal input into the machine. The Shot chamber has an opening to allow pouring metal with a ladle.
A hydraulic piston is integrated with the machine to force the molten metal inside with high pressure. The ladle can be considered part of the Cold Chamber Die Casting system as well.
METAL ALLOYS FOR COLD CHAMBER DIE CASTING
Cold Chamber Die Casting is designed to handle metal alloys with a high melting point. Commonly used alloys in the Cold Chamber Die Casting are,
Although Zinc can be cast with a hot-chamber machine, there are some Zinc alloys with a large percentage of Aluminum. It causes the melting temperature to increase and may require a cold-chamber machine instead.
Any other metal with a high enough temperature will require a Cold Chamber Die Casting machine as well. Which metal alloy you will need should be based on your quality requirements. We would recommend Aluminum alloys as a versatile, durable, and economic choice.
DIFFERENCE BETWEEN COLD CHAMBER AND HOT CHAMBER DIE CASTING
Now, this is where things get interesting. Cold Chamber Die Casting is more widely adopted than Hot Chamber Die Casting. But Hot Chamber Die Casting has more advantages over Cold Chamber Die Casting.
Hot Chamber Die Casting follows a similar procedure to Cold Chamber Die Casting. The only difference lies in how the material is melted in each process. Unlike Cold Chamber Die Casting, Hot Chamber Die Casting allows the metal to be melted inside the machine. That greatly reduces the cycle time for each casting and has the potential to boost your production capacity. Hot Chamber Die Casting allows about 4 to 5 castings per minute, while Cold Chamber can achieve only 2 to 3 castings per minute. All these facts sound pretty convincing. So, Hot Chamber Die Casting seems to be the better choice. Right? Well, that depends on your choice of metal. And the metal is decided based on your quality requirement for parts.
Some metal allows requires very high temperature for melting. And melting them inside the die casting machine has the risk of corroding it. That is not quite desirable as die machines are quite expensive. You could choose a low melting point alloy such as Zinc and that will allow you to use a Hot Chamber Die Casting Machine. But missing out on a cost-effective, durable, lightweight alternative like Aluminum is not an option.
If the requirements of your parts will be met by cold-chamber Aluminum Die Casting, You are better off sacrificing slightly faster cycle time to ensure better economy, quality, and durability for your parts.
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