Vibratory and tumbling finishing machines that use abrasive media to deburr or polish metal parts are generally classifiable here, provided their primary function is abrasive finishing rather than, say, cleaning or heat treatment. The machine's operating principle (abrasive media contact) and the material being finished (metal or sintered carbide) are the key classification anchors.

Sintered carbides (such as tungsten carbide) and cermets (ceramic-metal composites) are extremely hard materials used for cutting tool inserts and wear parts. Their inclusion in this heading reflects that finishing these materials requires abrasive processes similar to metalworking, even though they are not technically metals. Machines designed specifically for carbide insert grinding or lapping would fall here rather than in a general grinding heading.