How to Die Cast in a Hot Chamber: A Simple Guide to Die Casting

Casting is one of the most important steps in manufacturing, and die casting is a popular method. It’s used to create precision parts that can deliver consistent quality and repeatability. So how does it work?

Basically, you take molten metal and pour it into a mold that has been heated to just above its melting point. This allows for smoother surfaces and more interesting shapes than other methods such as sand casting. 

Now you know what die cast means! But there’s still a lot more information you might want to know about this process if you want to start making your own parts. Here are some other things you should know about die casting before trying it out for yourself.

Type of die casting

Die-casting machines are generally divided into 2 type die casting process, one is a cold chamber die casting, and the other is hot chamber die casting . based on which matel will be used. Today we want to talk about latter one.

How is The Hot Chamber Die Casting Working and Process?

Hot Chamber Die Casting Machine with Furnace

They use a hydraulic piston that pushes molten metal out of the furnace into a mold. The hot runner contains an alloy crucible as part of the machine itself and uses a flexible neck to inject material from the pot into the mold.

Hot chamber die casting process

When the chamber cylinder returns to the depressurized position, the molten metal is fed into the mold. Then the metal is pressed into the mold, the mold is opened after solidification, the cast part will be injected. Once solidified, the plunger retracts and the molten part is discarded, manually removed from the machine, or pushed out of the lid mold.  

Hot chamber die casting die tooling

Subsequently, the plunger retracts and the nozzle itself can be removed after opening the mold. Once solidified, the molds are opened and the casting is removed using the extraction pins. Most castings have a flash at the junction of the two mold halves.

Zinc hot chamber die casting manufacturer

Ejector pins push the casting out of the ejector die. As the plunger uncovers the filling hole, molten metal flows through the inlet to refill the gooseneck.

Zinc and magenesium Die casting process

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The Difference Between Hot Chamber Die Casting And Cold Chamber Die Casting

The cold chamber machine requires additional equipment, usually an external furnace and a ladle for pouring metal into the injection molding machine. The cold chamber process allows for higher density parts, but if the wrong partner is used, if the process is not optimized, the metal will cool too quickly in the cold chamber, which can lead to defects. A separate furnace is required to achieve the high temperatures required for the molten state of metals such as aluminum, magnesium, and copper, which is why some manufacturers prefer cold-chamber hot-chamber die casting.
The highest temperature of alloys that can be safely cast in the hot runner is about 450 degrees Celsius, including alloys such as zinc, magnesium, and lead. The cold room system is used for metals that melt at high temperatures, such as aluminum, copper, and magnesium. Each metal alloy has a different melting point, and metals with lower melting points are cast with hot runners.

The melting furnace is located in different locations for both processes. The only difference is that the metal is heated directly inside the casting machine and not in a separate furnace. This integrated furnace helps heat the molten metal and uses a hydraulic piston to force molten metal into the mold. After reaching the appropriate temperature, the molten metal exits the furnace through the gooseneck and is pushed into the mold by a hydraulic piston.    

Then the molten metal with the help of one plunger is pushed through a narrow feed channel (or gate) into the cavity of the mold itself with the application of a pressure from 7 to 207 MPa. The molten alloys are poured into a cold chamber and then injected into the mold using a high pressure plunger. The reusable steel mold used in the injection molding process is called a mold.    

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Hot Chamber Die Casting Advantage

Hot Chamber die Casting is an efficient manufacturing process for mass production of various shapes of parts, which are used in our homes and workplaces. Most pressure castings are made of non-ferrous metals, especially zinc, copper, aluminum, magnesium, lead, tin and tin-based alloys. Commonly used metal alloys include aluminum, copper, brass, magnesium and so on. Zinc is often used in the smelting of products in the automotive and medical industries.Magnesium castings can meet tight tolerances that are difficult or impossible to achieve with steel.

Suitable for complex thin-walled parts (> 0.05)
>> High dimensional precision and high process stability
>> Lightweight, high stability
>> Smooth surface and edges
>> Excellent processing performance, Low cycle time, Automatic Run.
>> High thermal conductivity
>> Good conductivity
>> Corrosion and weather resistance
>> A variety of surface treatments are possible
>> Low unit price for larger series
>> Reduce relatively high tool costs through optimized tooling structure on demand

Zinc and Mg die casting parts

Hot Chamber Die Casting Disadvantage

The high cost of molds and capital equipment costs limit the mass production of components for this process. Casting equipment and metal molds involve high capital costs, which often limit the process of mass production.

zinc die casting machine

Which Process will be Benefit for you?

if you want to produce zinc, magenisum,tin and lead castings, you should choose a hot chamber die casting machine because it corrodes easily and is more suitable for alloys with low melting points and correct fluidity. Disadvantages include slower production cycles, often due to the need to pour metal into the chamber.

Cold Chamber Die Casting,  The alloy is melted in a furnace located inside the equipment. The alloy for die casting is melted in a separate furnace located outside the equipment. Casting cycles are much shorter, so it has a large production capacity. It has longer casting cycles; hence the performance is lower. Suitable for low melting alloys. Suitable for high melting alloys. Has a shorter tool life. Minimal security measures required.

Conclusion

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