Decrease
in volume during the transition from the liquid to the solid state (s.
Solidification), the direct consequence of which is a volume deficit in
the form of porosity and pores (Figure 1).
The
volume deficit caused by shrinkage is compensated for by post-feeding
in the casting process, under the condition that all areas of the
casting are not yet blocked by already solidified melt. The casting
should be designed in such a way the localized accumulation of material
in remote parts is avoided. Today, such areas can be identified using
simulation calculations of the solidification process and can be removed
by changing the gate technology. However, production control for pores (partly radioscopic) is necessary for high-quality parts.