* Roughing Cutters in the round tool sector are better known as "RMR" cutters (Rapid Metal Removal). These tools are as per some of the other descriptions already posted on this thread. They (more commonly) will incoporate a typical spiral helix shape of multiple flutes which is a helix of between 20 and 40degrees. The cutting edge is broken into many segments that look like serations or multiple small radii * Tradesmen are of the opnion that the best RMR designs are ones that incorporate rounder profile serations * This is for obvious reasons that mainly lead to increased cutting edge strength * Having a broken edge has some benefts but also some draw backs * Ultimately, all you really get is the ability "To produce smaller chips per cm3/min (i3/min) of material machined" * By getting lots of smaller chips, you are able to get much better smarf removal/control and therefore, in some cases, are able to run a higher D.O.C (depth of cut) and/or f/z (feed per * The main reasons for RMR cutters being in existence is lower cutting forces, higher tool life and less bending when milling a shoulder at a high depth of cut *A broken edge greatly lowers the forces generated on the cutting edge. This can be a reduction of as much as 50% and an increase in tool life of as much as 50% can also be seen *The sacrfice is finish *