1. Foundry sand requirements

Foundry sand must meet two fundamental requirements:

• shaping in contact with a parent model, following all its details; this means that its initial state must be either powdery, liquid or liquid-plastic, or plastic; depending on this state, compaction is carried out either by simple gravity or by a mechanical clamping force (pressure, shaking, vibration, mechanical or pneumatic projection);

• maintaining this shape until the metal has completely solidified; this implies the acquisition of significant mechanical strength to withstand the static pressure of the liquid metal, as well as dynamic pressure (to avoid erosion phenomena), without impeding metal shrinkage during solidification.

Other properties are also required:

• refractoriness,...