Gear teeth inspection goes far beyond simple caliper measurements—it involves specialized metrology equipment that produces comprehensive reports.
The most common inspection methods include:
- (1) CMM with gear-specific software—a coordinate measuring machine probes multiple points along tooth flanks to reconstruct the actual gear geometry.
- (2) Gear roll tester (double-flank)—meshes the gear with a master gear and measures center-distance variation to detect runout, tooth thickness variations, and composite errors.
- (3) Single-flank roll tester—measures transmission error and individual pitch deviations.
- (4) Lead and profile checker—dedicated machines that trace tooth flanks in both longitudinal and involute directions.
The inspection report you receive typically includes: Pitch deviations (single pitch error, total accumulated pitch error)—critical for noise and uniformity; Profile deviation (form deviation, slope deviation)—indicates how closely the involute matches the theoretical curve; Lead deviation—checks tooth direction across the face width; Runout (eccentricity)—measures how much the gear deviates from perfect rotation; tooth thickness—determines backlash; and surface roughness (Ra/Rz). Each parameter is presented with actual measured values, tolerance limits, and a pass/fail indicator. For DIN 4 or AGMA Q12 gears, you will likely see a full-page “gear data sheet” with all these measurements, often including a polar chart for runout and a graphical trace of profile/lead deviations. Always request the raw data if you need to perform your own analysis.