In pressure die casting, metal is melted and forced
into steel dies. The metal hardens into the desired shape. Molten metal
is injected into a die cavity through a channel by movement of a
plunger. After a preset solidification time, the plunger reverses
direction, the part is ejected, and the machine is ready for the next
cycle.
Hot Chamber
This process involves the use of a plunger which traps a certain volume
of molten metal and forces it into the die cavity through a gooseneck
and nozzle. After the metal has solidified in the die cavity, the
plunger is withdrawn, the die opens and the casting is ejected. Metals
having low melting points such as Zinc, copper, magnesium and lead are
cast using Hot chamber die casting.
Cold Chamber
In this process molten metal is poured into the injection cylinder
manually by a hand ladle or by an automatic ladle. The metal is forced
into the die cavity at high pressures. High melting point alloys of
aluminum and copper are normally cast using cold chamber die casting.
High pressure die casting
The most commonly used process is the high pressure die casting, in
which molten aluminium is injected at high pressure into a metal mould
by a hydraulically powered piston. The machinery needed for the process
can be very costly and this high pressure die casting is only economic
when used for high volume production.
Low pressure die casting
Low pressure die casting uses a die which is filled from a pressurised
crucible underneath. The process is particularly suited to the
production of rotationally symmetrical products such as automobile
wheels.
Advantages of Pressure Die Casting |
Parts
without any joints can be made eliminating other processes such as
welding and fastening.
Integral
fastening elements such as bosses and studs can be included.
Good
dimensional accuracy and detail.
No
further machining required usually.
Low
cost.
Specifications for Pressure Die Casting |
Material:
Nonferrous alloys that have low melting points: aluminum, zinc,
magnesium, copper, lead, tin, silver.
Alternative
machines: Mill 3-Axis, other casting methods.
Tooling:
Requires custom tooling in shape of part.
Reducing
costs: Minimize size, complexity and material volume.
