The master model packed into sand to create the void that molten metal will fill. Patterns are typically made of wood, metal, or plastic. They are built slightly oversized to account for metal shrinkage as it cools, and feature drafted angles so they can be pulled cleanly from the packed sand without breaking the mold walls.
Check the draft angle on this pattern, the sand keeps tearing when we pull it.
A rookie mistake is forgetting to account for the shrink rate of the specific alloy when cutting the pattern.
Related terms
Corebox
A mold used to shape and pack sand into a solid core for creating internal cavities in a casting.
Core print
A projection on a casting pattern that creates a seat in the mold to hold a sand core securely.
Match
A contoured block or plate used to support a pattern and define the parting line of a mould.