U is for Unmöglich(Impossible) - where vibratory finishing reaches its limits.

Vibratory finishing is a very versatile process, but like any process, it has its limitations. A common misconception is that vibratory finishing can be used for grinding. Material removal is uneven across the entire surface, which categorically rules out the possibility of grinding. Another problem is the time factor. Reducing the dimensions of components by several tenths or hundredths of a millimeter would require an extremely long process. This process would be associated with very high costs. This method should only be used for surface finishing and deburring.

There are specific requirements or component geometries where the process reaches its limits. With narrow bores or complex internal geometries, insufficient machining occurs. As a result, the exterior is optimally machined, while the interior shows hardly any change. Further problems include grinding media jamming. Components with complex geometries usually have different bore diameters, which severely restricts the choice of grinding media. Thus, often only small grinding media remain as options, but these can jam in the internal geometries.

The process excels at rounding and deburring edges, but it cannot generate a precisely defined radius or chamfer. It's also important to note that when deburring edges is desired, the surface is always treated as well. The entire component is processed in this way; only through complex masking is it possible to treat specific areas or individual edges.

There are burrs that pose problems for vibratory finishing. These are usually so-called flash burrs. These burrs are very fine and are not cleanly removed; instead, in the case of vibratory finishing machines , they are often pressed against or folded over the workpiece edge. These burrs can detach in later process steps or during operation, which can lead to serious damage.