The core location clearance, also simply referred to as core clearance or core gap, is the dimensional difference between the core location dimension of the mold and the core location dimension of the core or the clearance of a movable metal or steelcore in its guide. For core clearance, EN 12890 provides the terms and dimensions illustrated in Fig. 1 and Fig. 2.
A minimum core location clearance is required in order to be able to set the core without damaging the mold (Fig. 3). However, the core must not be inserted into its location with too high of a clearance as this could cause unwanted flash formation (see Core flash). Moreover, if the core location clearance is unnecessarily large, this could lead to inaccurate wall thicknesses in the casting.
In contrast to the core location clearance, the core print clearance is the difference between the core print dimension of the pattern and the core print dimension of the core box.