Die Casting Process
Cold chamber dies casting is ideal for metals with high melting points and corrosive properties. When compared to hot chamber die casting, cold chamber dies casting solves the corrosion problem by separating the melting pot from the injector components. The process begins when molten metal is ladled from the furnace into the shot chamber through a pouring hole. Next, the plunger forces metal through the shot chamber into the die at pressures ranging from 2,000 and 20,000 psi.
With cold-chamber die casting, metal is first heated to achieve a molten state in a separate furnace. The molten metal is then transported to the casting machine where it’s fed into the machine’s chamber. The machine uses a pressurized plunger to force the molten metal into the cavity of the mold. This separated process is what directly differentiates cold chamber die casting from hot chamber casting.
Cold Chamber Die Casting
The cold chamber die casting process is a preferred manufacturing method for metals that have high melting points. Typically, this will include metal alloys of aluminum alloys, zinc alloys, brass, and copper. The requirements for cold chamber die casting include an outside furnace and a ladle to pour the molten metal. Cold chamber die casting methods are known for their ability to produce denser metal castings.
Advantages of Cold Chamber Casting
Cold chamber die casting is an effective, cost-effective process that can create a broad range of shapes and components compared to other types of manufacturing processes. The cold chamber die casting process can create parts that have a long service life and may be designed to complement the visual appeal of the surrounding part. Some of the direct benefits that the cold chamber die casting process can provide include:
Increased Strength & Weight
Cold chamber die-cast parts are stronger than plastic injection moldings having the same dimensions. Thin wall castings are stronger and lighter than those possible with other casting methods. Plus, because die castings do not consist of separate parts welded or fastened together, the strength is that of the alloy rather than the joining process.
Dimensional Accuracy & Stability
This process produces parts that are durable and dimensionally stable while maintaining close tolerances and heat resistance.
The cold chamber process provides complex shapes within closer tolerances than many other mass production processes. Little or no machining is required, and thousands of identical castings can be produced before additional tooling is required.
Cold chamber dies castings provide integral fastening elements, such as bosses and studs. Holes can be cored and made to tap drill sizes, or external threads can be cast.
Multiple Finishing Techniques
Cold chambered parts can be produced with smooth or textured surface finishes, and they are easily plated or finished with a minimum of surface preparation.
Hot Chamber Die Casting
Hot chamber dies casting machines are primarily used for zinc alloys, copper, lead, and other low melting point alloys. The injection mechanism of a hot chamber machine is immersed in a molten metal bath of a metal holding furnace. The furnace is attached to the machine by a metal feeding system called the gooseneck.
As the injection cylinder plunger rises, a port in the injection cylinder opens allowing the molten metal to fill the cylinder. As the plunger moves downward, it seals the port and forces metal to fill the cavity through the gooseneck and nozzle to the die cavity.
After the metal has solidified in the cavity, the plunger is withdrawn. The die opens and the casting is ejected.
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