The two types of die casting mold making machines are a hot chamber machine and cold chamber machine:

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Hot chamber die casting mold making machine - Hot chamber machines are used for alloys with low melting temperatures, such as zinc, tin, and lead. The temperatures required to melt other alloys would damage the pump, which is in direct contact with the molten metal. The metal is contained in an open holding pot which is placed into a furnace, where it is melted to the necessary temperature. The molten metal then flows into a shot chamber through an inlet and a plunger, powered by hydraulic pressure, forces the molten metal through a gooseneck channel and into the die. Typical injection pressures for a hot chamber die casting machine are between 1000 and 5000 psi. After the molten metal has been injected into the die cavity, the plunger remains down, holding the pressure while the casting solidifies. After solidification, the hydraulic system retracts the plunger and the part can be ejected by the clamping unit. Prior to the injection of the molten metal, this unit closes and clamps the two halves of the die. When the die is attached to the die casting machine, each half is fixed to a large plate, called a platen. The front half of the die, called the cover die, is mounted to a stationary platen and aligns with the gooseneck channel. The rear half of the die, called the ejector die, is mounted to a movable platen, which slides along the tie bars. The hydraulically powered clamping unit actuates clamping bars that push this platen towards the cover die and exert enough pressure to keep it closed while the molten metal is injected. Following the solidification of the metal inside the die cavity, the clamping unit releases the die halves and simultaneously causes the ejection system to push the casting out of the open cavity. The die can then be closed for the next injection.

 Hot chamber machine open 

Hot chamber die casting machine - Opened Hot chamber machine closed 

Hot chamber die casting machine - Closed

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Cold chamber die casting mold making machine - Cold chamber machines are used for alloys with high melting temperatures that can not be cast in hot chamber machines because they would damage the pumping system. Such alloys include aluminum, brass, and magnesium. The molten metal is still contained in an open holding pot which is placed into a furnace, where it is melted to the necessary temperature. However, this holding pot is kept separate from the die casting machine and the molten metal is ladled from the pot for each casting, rather than being pumped. The metal is poured from the ladle into the shot chamber through a pouring hole. The injection system in a cold chamber machine functions similarly to that of a hot chamber machine, however it is usually oriented horizontally and does not include a gooseneck channel. A plunger, powered by hydraulic pressure, forces the molten metal through the shot chamber and into the injection sleeve in the die. The typical injection pressures for a cold chamber die casting machine are between 2000 and 20000 psi. After the molten metal has been injected into the die cavity, the plunger remains forward, holding the pressure while the casting solidifies. After solidification, the hydraulic system retracts the plunger and the part can be ejected by the clamping unit. The clamping unit and mounting of the dies is identical to the hot chamber machine. See the above paragraph for details.

Cold chamber die cating machine open 

Cold chamber die casting machine - Opened Cold chamber die casting machine closed 

Cold chamber die casting machine - Closed

Machine specifications

Both hot chamber and cold chamber die casting machines are typically characterized by the tonnage of the clamp force they provide. The required clamp force is determined by the projected area of the parts in the die and the pressure with which the molten metal is injected. Therefore, a larger part will require a larger clamping force. Also, certain materials that require high injection pressures may require higher tonnage machines. The size of the part must also comply with other machine specifications, such as maximum shot volume, clamp stroke, minimum mold thickness, and platen size. 

Die cast parts can vary greatly in size and therefore require these measures to cover a very large range. As a result, die casting machines are designed to each accommodate a small range of this larger spectrum of values. Sample specifications for several different hot chamber and cold chamber die casting machines are given below.

Type Clamp force (ton) Max. shot volume (oz.) Clamp stroke (in.) Min. mold thickness (in.) Platen size (in.)

Hot chamber 100 74 11.8 5.9 25 x 24

Hot chamber 200 116 15.8 9.8 29 x 29

Hot chamber 400 254 21.7 11.8 38 x 38

Cold chamber 100 35 11.8 5.9 23 x 23

Cold chamber 400 166 21.7 11.8 38 x 38

Cold chamber 800 395 30.0 15.8 55 x 55

Cold chamber 1600 1058 39.4 19.7 74 x 79

Cold chamber 2000 1517 51.2 25.6 83 x 83

Alpine Mold is an aluminum die casting mold making manufacturer, having specialized in mold making for more than 25 years with good quality and pretty competitive price. Please contact us by kerry@alpinemold.com.