Breaker Cores

A breaker core (knock-off core) is a thin core with an opening in the middle, placed at the neck where the feeder sleeve connects to the part. By narrowing the section through which metal enters the part, it lets the feeder be knocked off with a single blow after casting.

This reduces the need for cutting or grinding the feeder, lowers fettling time and cost, and leaves a small feeder mark on the part surface. Because the narrowed section must stay open until the part solidifies, size and hole diameter must be chosen according to part modulus.

The breaker core must match the sleeve type and diameter. A wrongly sized choice can lead to early freezing of the feeder or breaking defects. To select the right size, share the sleeve information and consult us.