Permanent metal moulds preparation

If the shape of the casting cannot be easily made by the use of metallic core pins, sand cores may be used. For instance, sand cores are used to form the widening-out of centrifugal cast pipes. 

Permanent moulds are generally coated with a white or black wash these water-based release agents are refractory based in the case of the white one and graphite based for the black one. Their function is to provide protection of the die, to regulate die cooling by water evaporation, and to provide lubrication. They also act as parting compounds. 

In a few cases, blackening is provided by burning acetylene in the absence of air, producing acetylene black that partially sticks to the die. The non-adhesive black then has to be collected 

Permanent moulds (or dies) are generally not made in the foundry, although die-casting foundries do have a workshop for die assembly, maintenance and repair. This type of operation, however, does not generate any environmental effects. 

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Permanent (metal) moulds and pressure die preparation 4.3.5.1 Minimisation of release agent and water consumption... 

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