Kugelkopf effektiver Durchmesser

Ball nose effective diameter formula

A ball nose end mill cuts with a spherical tip. At shallow axial depths of cut (ap), the actual cutting diameter is smaller than the nominal tool diameter. Using the nominal diameter for speed calculations at shallow ap leads to incorrect SFM.

• Effective diameter De = 2 × √(D × ap − ap²)
• Effective SFM = π × De × RPM / 1000
• When ap ≥ D/2, effective diameter = D (full diameter)

How to use this Ball Nose Effective Diameter Calculator

Enter the nominal tool diameter and the axial depth of cut. The calculator shows the effective cutting diameter and the corresponding surface speed. Use the effective diameter to set correct RPM for shallow finishing passes.