Die Casting is a metal casting process that is characterize by the compulsion of molten metal under high pressure in a mold cavity.
The mold cavity has two rigid tool steel which has been machine in the shape and works similar to an injection mold during the process.
Most die casting is made of non-ferrous metals, especially zinc, copper, aluminum, magnesium, lead, paper and tin-based alloys.
Depending on the type of metal, a hot or cold-chamber machine is use.
The main die casting alloys are: zinc, aluminium, magnesium, copper, lead, and tin; although uncommon, ferrous die casting is also possible
The following is a summary of the benefits of each alloy:
- Zinc: The easiest metal to cast; High flexibility; High impact strength; Easily plated; Economical for small parts; Promotes long death life.
- Aluminum: Lightweight; High dimensional stability for complex shapes and thin walls; Good corrosion resistance; Good mechanical properties; High thermal and electrical conductivity; Maintains power at high temperatures.
- Magnesium: the simplest metal for a machine; Excellent power-to-weight ratio; The lightest alloy is usually insert.
- Copper: high hardness; High corrosion resistance; The highest mechanical properties of alloys die; Excellent wear resistance; Excellent dimensional stability; Strength near steel parts
- Silicone Tombstone: High-power alloy made of copper, zinc and silicon. Often investment is use as a substitute for cast steel parts.
- Lead and tin: high density; Extremely close dimensional accuracy; Corrosion is use for special forms of resistance.
While creating the parametric model of die casting, many geometric features should be considered:
- The quantity of a DRAFT slope or cone or other parts of the dying cave is given to allow for easy rejection of casting by dying. All die-cast surfaces that are parallel to the starting direction of the dying need to be draft for proper rejection of casting by dying. Die Castings, which facilitate proper draft, are easy to remove from die and as a result of high quality surfaces and more precise finished product.
- A FILLET is the winding junction of two surfaces that otherwise would have been found on a sharp corner or edge. Fillets can be added to a die casting to remove just undesirable edges and corners.
- A PARTING LINE represents the point at which the two different sides of the mold come together. The location of the parting line defines which side of the death is the cover and which is the ejector.
- BOSSES are add to die to serve as stand-ups and growing points for casting, which will need to be mount. For the maximum integrity and strength of die castings, the owners should have the thickness of the universal wall.
- RIBS are add to provide extra support for design in die casting, which requires maximum power without wall thickness
There are two types of die casting machines: Hot-Chamber Machines and Cold-Chamber Machines.
Hot-Chamber Die Casting:-
Hot-chamber die castings, also called gooseneck machines, rely on the pool of molten metal to feed the dead.
At the beginning of the cycle, the piston of the machine is withdrawn, which allows the molten metal to fill “gooseneck”.
Pneumatic- or hydraulic driven piston then forces this metal to get out of Gooseneck.
Cold-Chamber Die Casting:-
They are used when casting alloy can not be used in hot-chamber machines; These include zinc, alloy with a large structure of cookies, zen and active.
The process for these machines starts with melting the metal in a separate furnace.
An exact amount of stony metal is taken to the cold-chamber machine, where it is fed into an unscheduled shoot chamber (or injection cylinder).
This shot is then operated in a dye by recording or Coimbatore piston.