Le macchine per pressofusione possono essere principalmente suddivise in due diverse tipologie: macchine per pressofusione a camera calda e macchine per pressofusione a camera fredda. La differenza sta in quanta forza possono sopportare. L'intervallo di pressione tipico è compreso tra 400 e 4000 tonnellate.
pressofusione a camera calda
Hot chamber die casting, sometimes called gooseneck die casting, involves a pool of molten, semi-liquid metal that fills a mold under pressure. At the start of the cycle, the machine's piston is retracted, allowing molten metal to fill the gooseneck. A pneumatic or hydraulic piston squeezes the metal and fills it into a die. The advantages of this system include high cycle speed (approximately 15 cycles per minute), ease of automation, and ease of melting the metal. Disadvantages include the inability to die-cast metals with higher melting points, as well as the inability to die-cast aluminum, which would carry iron out of the molten pool. Thus, hot chamber die casting machines are generally used for alloys of zinc, tin and lead. Moreover, hot chamber die casting is difficult to use for die casting large castings, which are usually die casting of small castings.
pressofusione a camera fredda
Cold chamber die casting can be used when die casting metals that cannot be used in the hot chamber die casting process, including aluminum, magnesium, copper, and zinc alloys with higher aluminum content. In this process, the metal needs to be melted first in a separate crucible 2 . A quantity of molten metal is then transferred to an unheated injection chamber or nozzle. These metals are injected into the mold by hydraulic or mechanical pressure. The biggest disadvantage of this process is the long cycle time due to the need to transfer the molten metal into the cold chamber. Cold chamber die-casting machines are also divided into vertical and horizontal types. Vertical die-casting machines are usually small machines, while horizontal die-casting machines have various models.
