ZEISS Automated Defect Detection

A pore is a spherical or ellipsoidal cavity with mostly smooth walls inside the component. Depending on their origin, they can contain air, vapor, hydrogen, or other gases (e.g. from lubricants). They often occur in upper casting layer, but in poorly evacuated areas or undercuts they can be distributed within the whole casting.

Cold run occurs preferably on flat surfaces with relatively low thickness. This can result in a separation of the cohesion, leaving holes, areas that have not run out, but also rounded edges and overlaps. In die casting, cold run can be seen on very fine and thin surface slates.

Damage to the casting core, such as breaking off or breaking apart, leads to defective component geometries during the casting process, which can have a significant impact on functionality. This can be caused by suboptimal molding material composition or excessive thermal stress.

Shrinkage holes occur through the shrinkage process during the solidification of melted metal. The degree of shrinkage depends on the melting point of the material. As the outer shell and sprue of a casting generally solidify early, volume deficits can be formed in the interior of the casting. Shrinkage is characterized by rough and spongy surfaces and is more elongated.

Micro-porosity can be understood as an accumulation of small shrinkage holes (micro-shrinkage / interdendritic shrinkage), which can create chains and lead to leakages. This porosity appears in a CT scan with lower resolution as spongious areas.

Through gravity casting and low-pressure die casting, residuals of sand (or salt) cores may remain in the interiors of parts, when the coring process is not sufficient.

If, for example, defects occur in the positioning of the core in the mold before casting, or if the cores shift during the casting process, the geometries of the casting no longer match the CAD model.

During rough machining of the component (e.g. saw cut on the feeder), aluminum chips are produced which can fall into the component. Likewise, small protrusions (feathers) can break off during coring and remain in the component. These aluminum residues can lead to defects in the cooling system, for example, during subsequent operation.

Inclusions are partially or completely embedded impurities in the cast component which are usually denser than the base material. They are caused, for example, by foreign bodies in the casting mold or by contaminated casting material.