Hot Chamber vs Cold Chamber Die Casting
In a previous article, we discussed the best metals for producing die-cast parts. As part of that discussion, we briefly mentioned which metals were best for hot-chamber and cold-chamber die casting. Here, we’ll go over the differences between these two types of high pressure die casting, their benefits, and which ones are best for particular situations.
Both of these processes are very similar, as they are derivatives of high pressure die casting. The main difference is the location of the furnace for the equipment in which the metal is melted. While they both have advantages and disadvantages, each one is excellent when used in the right applications.
Hot Chamber Die Casting
Hot chamber die casting is a type of high pressure casting used for metals with a low melting temperature. The furnace is connected to the rest of the machine as a result, because the relatively lower heat is much less likely to damage the equipment. Hot chamber die casting is much more efficient than its cold chamber counterpart, because there’s no waste when transporting molten metal from the furnace to the die.
The most popular metal for hot chamber die casting is Zinc. Its low melting point makes it an excellent choice, and it has many other benefits as well. Zinc has good electrical and thermal conductivity. The metal is highly fluid in its molten form, improving dimensional tolerance and allowing for complex geometries and thin walls.
Magnesium is another popular choice for this type of high pressure die casting. It is lightweight, strong, and recyclable, and like zinc, it has high electrical and thermal conductivity. Magnesium also has a unique characteristic–it can shield against radio frequencies and electromagnetic interference.
The main disadvantage of hot chamber casting is its limited material choice, as it’s only suitable for metals with low melting points. This also makes it best for high volume production, due to die casting costs. However, hot chamber die casting has a much quicker production cycle, since there is a quicker transfer of metal from the furnace to the die, and a lower melting temperature means quicker melting and subsequent solidifying. There’s also much less waste in both material and labor.
Cold Chamber Die Casting
Cold chamber die casting is preferred for metals with high melting points. These extreme temperatures pose a risk to the die tools, so the furnace is separate from the rest of the equipment. Once the metal has been melted in the furnace, it’s transferred to the die to solidify.
Cold chamber die casting is a versatile type of high pressure die casting, able to work with a variety of metals. The most common die-cast metals processed with it are aluminum alloys, zinc alloys, brass, and copper. Because it’s a somewhat slower process than hot chamber casting, it’s best for lower production volumes of parts. Parts cast in cold chambers have a long service life and increased strength. They also have high dimensional accuracy, no matter the shape or type of component, as well as increased stability, with close tolerances and good heat resistance. The downsides are its lower production efficiency, due to the furnace being separated from the rest of the equipment, and shorter die tool life because of the high temperatures needed to melt these metals.
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