Productivity in drilling is strongly related to the penetration rate,vf.
Cutting speed for indexable drills
– One central and one peripheral insert
The cutting speed declines from 100% at the periphery to zero at the center. The central insert operates from cutting speed zero to approximately 50% of vc max. The peripheral insert works from 50% of vc max. up to 100% of vc max.
Cutting speed for solid carbide drills and exchangeable tip drills
Two edges from the center to the periphery.
A solid or brazed carbide drill is ground slightly tapered on its outer diameter supply clearance, which prevents the drill from jamming in the hole.
l4 is the maximum recommended hole depth.