The difference between the measured tooth profile and the design profile, traced from the start of active profile to the tip. It is split into total profile deviation, a slope deviation that shows the profile tilted as if the pressure angle were off, and a form deviation that shows waviness and bumps. Slope errors point to machine or cutter setup, while form errors point to tool wear or vibration.
Profile deviation is all slope, every tooth tilted the same way, so check the dress angle on the wheel before you blame wear.
Also heard as
- profile error
- involute error
Related terms
Involute
The curve traced by the end of a taut string unwound from a circle, the shape of almost every gear tooth flank.
Trace
The printed plot of a tooth's measured profile or helix from a gear checker, read against tolerance bands.
AGMA quality number
A grade that sets how accurate a gear's teeth must be, on either the Q-number or the A-number scale.
Tip relief
A slight removal of material near the tooth tip so each tooth enters mesh smoothly under load.