Number of cutting edges

As the number of cutting edges increases, the feed per revolution can be increased, improving machining efficiency. Additionally, with more cutting edges the length of cut before reaching maximum tool life also increases, therefore extending overall tool life.

However, an increase in the number of cutting edges narrows the distance between cutting edges, and so makes conditions worse for chip discharge. Additionally, as the number of cutting edges increases so too does the cutting resistance.


Poor chip discharge, where chips are caught in the flutes can adversely affect surface finish. If chip discharge conditions worsen further, the resulting chip jamming can damage the cutting edges or completely break the end mill. Therefore, with a large width of cut, ae, or when slotting, an end mill with less cutting edges is generally used.

The table shows the effect of the number of cutting edges.

When machining thin walled workpieces or under conditions of low rigidity, care should be taken against cutting resistance. An end mill with a small number of cutting edges should be chosen to prevent vibration.