Die-Casting

Die-casting differs from sand casting in that a metal mould is used rather than a sand mould. The tooling is also different to that previously discussed in that the die is the inverse or female of the shape that will be produced. Most metals can be die-cast but the main ones are zinc, aluminium and magnesium alloys.The molten metal is forced into the die under pressure so the die is usually fairly substantial, weighing several tonnes, and is made from special alloy steels. The finish obtained with this process is very good with tolerances of + 0.05mm on a 25mm dimension. It is, however, expensive and only viable for production quantities greater than 10000.


Rotational Casting

In this process molten metal, or more commonly, plastic is poured into a mould which is then spun forcing the liquid material onto the surface of the mould. This is how some metal pipes, plastic footballs and moulded furniture is made.