Accurate die casting

Accurate die casting

Die casting is the process of forcing molten metal under high pressure into mold cavities (which are machined into dies). The so-called accurate die casting is one kind of die casting with accurate casting dimensions. Most accurate die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys, although ferrous metal die castings are possible. The main accurate die casting alloys are: zinc, aluminium, magnesium, copper, lead, and tin. Specific dies casting alloys include: ZAMAK, zinc aluminium, AA 380, AA 384, AA 386, AA 390, and AZ91D magnesium. The accurate die casting method is especially suited for applications where a large quantity of small to medium sized parts are needed, ensuring precise surface quality and dimensional consistency. This level of versatility has placed die castings among the highest volume products made in the metalworking industry.

Like the die casting, the accurate die casting can also be done using a cold chamber or hot chamber process. In a cold chamber process, the molten metal is ladled into the cold chamber for each shot. There is less time exposure of the melt to the plunger walls or the plunger. This is particularly useful for metals such as Aluminum, and Copper (and its alloys) that alloy easily with Iron at the higher temperatures. In a hot chamber process the pressure chamber is connected to the die cavity which is immersed permanently in the molten metal. The inlet port of the pressurizing cylinder is uncovered as the plunger moves to the open (unpressurized) position. This allows a new charge of molten metal to fill the cavity and thus can fill the cavity faster than the cold chamber process. The hot chamber process is used for metals of low melting point and high fluidity such as tin, zinc, and lead that tend not to alloy easily with steel at their melt temperatures.