At the beginning of the 20th century, with the rise of the automotive sector, the production of high-pressure aluminum injection molds became increasingly common for obtaining parts. Today, this system has acquired a primary role in the industry for the development of countless components, whether in the automotive sector or any other field.
There are two methodologies that explain how metal can be melted inside the mold: hot chamber and cold chamber. Want to know more about tooling and mold creation? Click here.
Melting Metal Inside the Mold in Hot Chamber Machines
In hot chamber machines, the furnace itself is an integral part of the metal injection into the mold, so the metal melting occurs inside the chamber at high temperatures. For this reason, these machines should not produce parts from materials like aluminum, copper, or magnesium alloys, as they can damage the mold when these materials are above their melting point.
The molten metal undergoes less oxidation than in cold chamber machines, and therefore fewer contaminants are produced by atmospheric exposure. Since the metal is submerged, the filling process occurs:
Automatically.
Eliminating variation.
Reducing time.
Facilitating metal temperature control.
Requiring less injection pressure.
Being subjected to less stress.
With the cylinder submerged in the molten metal, the piston pushes the metal volume toward the outlet, discharging it into a hot mold. When the injected metal solidifies, it is then cooled in a quenching chamber with water or oil, with maximum pressures of up to 35 MPa.
Melting Metal Inside the Mold in Cold Chamber Machines
This system is increasingly used, where the metal melting occurs outside the injection system. During the injection process, the temperature is lower than that of the alloy’s pouring, resulting in minimal contact with it. The alloys are melted in a separate furnace and then poured into the injection chamber using a special device that introduces the necessary amount into the mold for creating each part. With cold chamber filling machines, we can process alloys such as aluminum or zinc. The advantages of using these chambers are:
Higher pressures are achieved.
Faster speeds are reached.
More compact parts with better mechanical properties are obtained.
Cold chambers require less maintenance than hot chambers.
Injection can be performed both vertically and horizontally, allowing us to manufacture lightweight alloy parts with higher melting points than in hot chambers.
Horizontal chamber machines enable shorter production times because higher pressures can be applied to the metal.
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