The lead angle (𝜙) is the angle at which the flanks of a thread run relative to the spindle axis. It is a central parameter for feed rate, force transmission, and self-locking.
The lead angle influences:
Feed Rate
Large lead angle → greater axial movement per revolution → faster feed
Small lead angles → smaller movement → finer resolution, higher precision
Force Transmission & Self-Locking
Small lead angles → mechanical advantage, higher self-locking, less backlash
Large lead angles → lower force transmission, not self-locking
Efficiency
Steeper angles reduce friction losses, especially in ball screw drives
Positioning Accuracy
Shallow angles enable finer movements and more precise positioning