A shrinkage cavity is a cavity formed during solidification of a cast part. In casting processes, shrinkage cavities can form in isolated or clustered form due to temperature-dependent material volume contraction. Indentations on the surface can also be a consequence of this volume reduction; these are also called shrinkage cavities. If a casting has shrinkage cavities, this is referred to as shrinkage shrinkage. The formation of shrinkage cavities cannot be completely avoided. Instead, geometric sprue bodies, so-called risers, are usually included in the design of the molds in whose shape the shrinkage volume deficit is to be placed. Thus, after casting solidification, any shrinkage is found only in the riser, which can be removed in the fettling process of the castings. A susceptibility to shrinkage cavities depends on the material. They are divided into open and closed shrinkage cavities. As a casting defect, blowholes can have costly and material-intensive consequences, which is why it is worthwhile to check the casting and curing behavior of castings with a casting simulation. There are various molding and casting technology measures to avoid blowholes. With an industrial CT scan, blowholes can be detected quickly and precisely.