Rotary engraving is the term used to describe engraving done with a rotating cutting tool in a motorized spindle. The tool, or cutter, cuts into the surface of the material to a predetermined depth and produces a groove of the same shape and dimension of the cutter. Rotary engraving can be performed on a wide variety of materials with plastic, brass, bronze and aluminum being the most common in the awards industry.  Deep paint filled aluminum brass and bronze are a good example