Cores are parts of a mold used for design and implementation of inner and outer contoures in case of pronounced undercuts and/or back drafts.
Production of cores generally is performed simultaneously with mold production but in specific manufacturing areas. Moreover, cores must also meet special technologic requirements. The still prevailing classification of processes into mold production and core production, nowadays is not fully applicable any more, despite a few distinctive technological characteristics. This means that processes based on cold-hardenable molding materials are used for manufacturing of both molds and cores. Applcation of the shell molding process is also suitable for production of both molds and cores.
Correspondent to mold manufacturing, cores are classified by their usage into cores for single use (lost cores) and permanent cores that can be multiply used. However, permanent cores are limited in use, particularly in terms of their design. Other problems result from the risk of sintering to the cast part, complicated ejection after casting and potentially occurring shrinkage impairment.
Cores can be classified as listed below, depending on their purpose of use: