The moulds need to be preheated up to 200 degree Celsius prior to metal being poured in cavity. The cavity pattern of those moulds does not follow similar rules of shrinkages as in sand casting moulds. The reason is, metal moulds heat up and expand during the pour therefore, the cavity does not expand as in sand castings. Though care must be taken to keep correct thermal balance; by having outside water cooling.

Permanent mould castings are not as flexible as sand castings in using various designs that are cost effective. While producing 1000 or more parts the cost per piece is less. But breaking even is subject to complexity of part. More complex parts are suited to permanent moulds.

Normal part size may vary from 50 grams to 70kg. Basic materials are aluminium magnesium and brass plus their alloys. The parts are gears, splines, wheels, gear housings, pipefitting and vehicle pistons.

Slush casting:

It is a special method of permanent mould casting in which melted metal is not completely solidified. After getting the required wall thickness, the not yet solid melted metal is poured out. This is used for making hollow ornamental objects like lamps and statues made.

Corthias casting:

This is another method of permanent mold casting. In this a plunger is utilized to push down the melted metal to make the sprue hole. This makes it possible for you to get thinner walls and greater details to be made.

Low pressure permanent mould casting:

It is yet another version of permanent mould casting. In this gravity is not used for pouring melted metal into the mould but a low pressure of up to 1 atmosphere gas is put to melted metal. This continuous pressure on metal causes the mould to be completely filled and as a result there is no shrinking after cooling. In this process thin wall castings can be made. Mechanical properties are 50% better than permanent mould casting. As no riser is utilized the yield is usually higher as the metal in pressurized feed tube is still melted and the mould is ready for next shot right away.

Vacuum permanent mould casting:

This is another method of permanent mould casting. It is similar to low pressure casting, in which vacuum is utilized in place of pressure. Thin walls can be achieved as in low pressure mould casting. Along with it yields are better as no risers are utilized. As vacuum is utilized in its place, the purity of metal is kept. The mechanical properties are 10-15% better than permanent mould casting. The size of castings ranges from 4.5kg-200kg.

It is a permanent mould casting powdery mould releasing agent. As per this discovery has a granulated or powdery mixture of a lubricant, an organic polymer and a metal soap, in which the lubricant is coated with polymer or metal soap. Due to this the mould releasing agent permits production of high quality in a permanent mould casting.

In a spray system for spraying and applying a powdery mould casting agent on to both inside surfaces of a moveable metal mold and fix metal mould for a permanent mould casting tool. A spray method of permanent mould casting agent of which a spray head is given to electrostatic spray gun is fitted to a feeding port so as to shut it tightly under a stage where a moveable and stationery metal mould are closed.