Sand core that can be produced in the form of both solid core and hollow core, and which determines the outer shape of the casting either in full or in parts (Fig. 1).
In case that the casting includes undercuts that cannot be realized by means of a joint planes, these can be achieved by means of outer cores. In this way, molding work without additional joint planes becomes possible. In horizontally parted molds, outer cores are often designated in accordance with their position or orientation (Fig. 2). A special type of outer core is the inset core.