A core is a device used in casting and moulding processes to produce internal cavities and reentrant angles (an interior angle that is greater than 180°). The core is normally a disposable item that is destroyed to get it out of the piece.^[1] They are most commonly used in sand casting, but are also used in die casting and injection moulding.

For example, cores define multiple passages inside cast engine blocks. One model of GM V-8 engine requires 5 dry-sand cores for every casting.^[1]

 

Materials required to make cores[edit]

• Core sand
• Bentonite clay
• Pulverized coal
• Resin oil