Aluminium casting techniques
Over the years, Perla AluCast has become specialised in three different casting methods, which it has fully focused on:
Our factories in India and China have a wide range of injection-moulding machinery available. The labour-intensive gravity die casting and low pressure casting take place exclusively in India.
Because our specialists know all about these three casting techniques and have built up extensive experience with them, while designing the end product or the casting mould we can take into account the key characteristics that play a role in these different casting methods.
Gravity die casting is the aluminium casting technique that involves pouring liquid aluminium into the steel mould (the Gravity die). The mould usually consists of two or more parts. Gravity die casting is almost always carried out manually using a ladle. Gravity die casting is mainly used to manufacture somewhat simpler aluminium castings in large series. Because of this more labour intensive casting method, we only use it in India.
Advantages of gravity die casting >
Low pressure casting looks like “normal” gravity die casting, except that the mould is positioned on top of the oven. So the mould is not filled under the influence of gravity. With a low underpressure of up to around 1 bar, the liquid metal flows out of the oven into the mould through a riser pipe. This process is therefore more controlled and, due to the gradual filling of the mould, air and gases can easily escape through the vents at the top of the mould. This ultimately results in a higher quality of aluminium casting.
Characteristics of low pressure die casting >
With high pressure die casting (or injection casting), the liquid aluminium is injected into the steel mould under high pressure. Injection casting is a fully automatic process. An injection-casting machine consists of two large plates on which half of a mould is attached. When the machine is closed, the two mould halves are pressed against each other with great force to prevent the mould from opening during the afterpressure phase. The injection casting process is implemented in 3 phases:
After the liquid aluminium has been poured into the shot cylinder, the pouring duct is first filled relatively slowly as far as the product cavity. Then the product cavity is filled at high speed. This takes place in just a few milliseconds.
The last casting phase is the compression phase: During the process, very high pressure is applied to the still liquid aluminium (up to as much as 1200 bar) to compress the product. After the aluminium has solidified, the machine opens and the product is ejected.
The great advantage of injection casting is that more complex shapes can be made and can have very thin walls. Because the aluminium is injected into the mould under higher pressure, the measurement accuracy is high and the surface quality is excellent.
Advantages of aluminium high pressure die casting >