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Casting Die Casting Processing Metals Materials



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Casting is a very common method to process materials like metals and polymers. The process is used to produce shaped materials repeatedly; hence it is a very useful process in mass productions. In the past when there was no casting process, shaping materials takes not only a long time, but it also involved intensive manual work. One of the main issues with these manual processing is the variable quality of work produced.

Imagine the keys of the keyboard of the PC you are using now are all of slightly-different shapes and sizes; you would be visiting your PC service centre rather often (due to poor fitting of the keys resulting in too much friction that wears out the parts quickly), and each sent-in for repair would take a long time to complete, as the servicemen have to make the keys, try to fit into the keyboard unit, then make necessary machining/shaping, one-by-one.

That sounds really bizarre, and it is certainly unimaginable today, an era where time is valued as much as money.

Die casting is one of the metallurgical casting methods used since a long time ago. The mold that gives the molded material shape is called a die. The metal material has to be melted, then injected into the empty space (called cavity) of the die and then pressed under high pressures over a certain processing time to allow the material to maintain its shape and to avoid flowing during freezing (solidification).

Features of the die casting operation include the plunger, chamber, and the die, which is termed as the heart of the process.

PLUNGER

Most important feature of the die casting process is the plunger, which serves two purposes: 1) for injection of the casting material into the die cavity. 2) To plug the liquid material in the cavity during solidification. It should also be noted that this plunger is usually pressurized to ensure complete filling of the cavity, so that the shaped materials are formed properly.

CHAMBER

Contrary to the straight cylinder seen in cold chamber casting, the chamber of hot chamber casting takes the shape of a goose-neck (an equipment of the same name) which serves as a feed system for insertion of the melted metal into the die.

HOT CHAMBER DIE CASTING

In hot chamber die casting, there are additional components like the metal pot that hold the pool of liquid metal feed. And it is directly connected to the goose-neck so that feed can be sucked into the chamber and get injected into the die by the action of the plunger. This makes the goose-neck or chamber always heated by the liquid metal due to direct connection to the metal pot. This is how the process got its name.

Due to the direct connection to a feed pool that takes the form of a metal pot, hot chamber die casting has a higher rate of production as the process is simpler. Hot chamber casting is usually used for low melting point metals and metals that do not erode the plunger and chamber parts. This because the constant heating for higher melting-point metals in an open environment can be quite energy consuming and the erosion of the equipment can take place faster at higher temperatures.

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