Abstraction of heat in accordance with the temperature gradient.

The liquid casting material is left to cool in the mold. Solidification begins as soon as the material reaches its liquidus temperature. Solidification is completed as soon as the material reaches its solidus temperature. The solidified casting continues to cool in the mold or after demolding. The cooling effect is thus influenced by the three concepts of thermal conduction, thermal radiation and convection.

Additional references:
Cooling rate
Cooling curve
Cooling stress
Cooling time