Introduction
A cold chamber die casting machine is widely used for casting metals with high melting points such as aluminum, magnesium, and zinc alloys. Unlike hot chamber casting, where the injection system is submerged in molten metal, the cold chamber method introduces liquid metal into a separate chamber before high pressure forces it into the mold. This design improves durability and supports casting of alloys that would otherwise damage hot chamber systems.
According to Vietnam die casting supplier, cold chamber machines are essential for producing automotive components, heavy machinery parts, and industrial equipment. Three main types of machines are used: horizontal, vertical bottom-up, and vertical top-down.
Vertical Pressure from Top to Bottom
This type can be considered the direct pressing method. The working principle operates as follows. When plunger 1 rises, liquid metal enters the press chamber. At the tightening position, part of the metal solidifies, preventing entry into mold cavity 1. As the piston moves down, high pressure pushes the solidified portion downward and forces liquid metal into mold cavity 3.
This approach is effective for casting zinc, magnesium, and aluminum components. It ensures strong filling under pressure but requires precise control of timing to avoid solidification defects.
Vertical Pressing Type from Bottom Up
In this type, piston 1 first descends and allows liquid metal to flow into the press chamber. As the piston rises past the inlet hole, the filling process begins and continues until the mold cavity is completely filled. The casting solidifies under controlled conditions.
The key advantage is that heavy castings can be formed efficiently. However, because the mold opens horizontally, the casting remains in one half of the mold after solidification. As a result, a thrust system must be used to eject the finished part. This method is especially suitable for large and heavy castings.
Horizontal Cold Chamber Die Casting Machine
The horizontal machine is the most common type of cold chamber die casting machine. Its cycle includes four main stages:
Stage 1: Feeding
The mold is locked tightly by a hydraulic cylinder system. Liquid metal is poured into the shot sleeve, and the plunger seals the filling hole. At this point, plunger speed and pressure are kept low—just enough to overcome friction and guide the liquid metal forward.
Stage 2: Cavity Filling
As the plunger advances, its speed increases to the maximum (v2) and pressure rises sharply to p2. The molten metal is then injected into the mold at very high speed, ensuring complete filling in a short time. The cooling system of the mold immediately begins solidifying the casting.
Stage 3: Mold Opening
After solidification, the mold opening system separates the movable half from the stationary half. At the same time, the side cores withdraw, leaving the casting attached to one side of the die.
Stage 4: Product Ejection
The ejector system pushes the casting out of the mold. The plunger then retracts, preparing the chamber for the next shot. Once the casting drops, the mold halves close again, starting a new cycle.
Conclusion
The cold chamber die casting machine remains one of the most important tools in modern manufacturing. Vertical top-down and bottom-up machines handle specialized applications such as heavy or precision castings, while the horizontal machine dominates high-volume production. Together, these systems support the casting of aluminum, magnesium, and zinc alloys with efficiency, accuracy, and reliability.
