Bearing / Ball-Screw Life

L10 service life for ball screws and linear guides / belts.

Screw Ca (dyn. rating)

Screw Pc (equiv. load)

Screw speed (rpm)

Life constant (10^6 rev)

Belt Ca (rated load)

Belt Pc (equiv. load)

Belt speed (m/min)

Belt pitch circumference (mm)

Ball screw : L10h = (Ca/Pc)^3 · a3 · 10^6 / (60·n)
Belt (approx): L10h = (Ca/Pc)^1.1 · 10^6 / (60·n_belt)
n_belt = v[m/min]·1000 / pitch_circ[mm]

L10h is the life at which 90% of bearings still survive.