A core is a manufactured sand aggregate inserted in a mold to shape the interior of that part of a casting, which cannot be shaped by the pattern. An example is a hole horizontally through a casting.
Three types of cores are manufactured, shell cores, CO2 and nobake cores. Shell cores are the most efficient and economical method of incorporating cores into sand casting molds. The shelf life of shell cores runs into months. CO2 and nobake cores are used either for large castings or for short production runs when the customer does not want the up-front cost of manufacturing shell core boxes and would rather have the cost incorporated into the casting price. The cost is more expensive than shell cores. The shelf life of a CO2 core is very short and the cores must be used within 24 hours of manufacture. Nobake core have an extended shelf life.
Shell cores are manufactured on manual or semi-automatic Dependable Shell Core Machines ranging in size from 100’s to 400’s.