Die casting hot-chamber

Figure 18.3. High-pressure hot-chamber die-casting machine...

Hot-chamber die casting shot cylinder immersed in molten metal and then forced using a separate ram. Used for low melting temperature metals due to erosive nature of molten metal. Can be either plunger or goose-neck type. 

Injection metal assembly variant of hot-chamber die casting for the assembly of parts such as tubes and plates, cable terminations and to act as rivets by injecting zinc or lead alloys into a cavity in the assembly. 

Figure 2.46 Cold-chamber and hot-chamber high-pressure die-casting devices [42, US EPA, 1998]...

Hot-chamber HPDC machines comprise a molten metal reservoir, the die, and a metaltransferring device, which automatically withdraws molten metal from the reservoir and forces it under pressure into the die. A steel piston and a cylinder system with a gooseneck is used to create the necessary pressure within the die. A gooseneck machine utilises a cast iron channel to transfer the molten metal from the reservoir to the die. Pressures can range from a few bar to over 350 bar. Hot-chamber techniques are mainly used for zinc alloys and magnesium alloys. 

Two principal types of machine are used in the production of die-castings by high-pressure methods hot-chamber and cold-chamber machines. 

Hot-chamber machines are most widely used with zinc alloy at pressures in the region of 100 bar. The metal temperature in the cmcible is between 400 C and 425 C, and the die temperature, which should be the lowest that will give castings of good quality, is usually from 180 C to 260 C. Casting size can vary from 0.01 kg to 25 kg. 

ZL3 is a general-purpose alloy used in hot-chamber high-pressure die-casting for the engineering and automotive industry, household equipment and utensils, office equipment, locks and toys. It is easily machined, polished, lacquered and electroplated for decorative and functional purposes. 

Silicon carbide is manufactured in many complex bonded shapes, which are utilized for super-refractory purposes such as setter tile and kiln furniture, muffles, retorts and condensers, skid rails, hot cyclone liners, rocket nozzles and combustion chambers, and mechanical shaft seals. It is also used for erosion- and corrosion-resistant uses, such as check valves, orifices, slag blocks, aluminum die-casting machine parts and sludge burner orifices. Electrical uses of SiC include lightning arrestors, heating elements and nonlinear resistors. 

Fig. 8.17 Typical die castings (a) hot-chamber zinc alloy die castings (from Ref 2, p. 177) (6) cold-chamber ahiminium alloy die castings of an automobile part, shown with slug and runner attached (from Ref. 2,p. 100) (c) low-pressure aluminium alloy casting of a cyhnder head (from Ref. 2, P- 166).

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