What Analytical Gear Inspection Actually Measures

"Inspected to AGMA 15" only means something if the inspection measures the right things. Analytical gear inspection goes well beyond checking a few dimensions with calipers. It characterizes the actual geometry of the tooth and compares it to a computer model of the ideal gear. Here is what those machines measure, and why each parameter matters.

Involute profile

The profile trace measures how closely the tooth flank follows a true involute curve from root to tip, including intentional modifications such as tip relief and crowning. Profile error is a primary source of transmission error, which translates directly into noise and vibration in a running gear set.

Lead (helix)

The lead trace measures the tooth across the face width. Lead accuracy determines whether load is shared evenly along the tooth or concentrated at one end, which is a leading cause of premature pitting and tooth breakage when it's wrong.

Pitch and index

Pitch measurements check the spacing from tooth to tooth (single pitch) and the accumulated spacing around the whole gear (index). Pitch errors create once-per-tooth excitation and uneven load sharing, degrading smoothness at speed.

Runout and tooth thickness

Runout captures eccentricity of the teeth relative to the mounting bore, which produces once-per-revolution vibration. Tooth thickness, measured over wires, over pins, or by span, sets the backlash the gear will have at its operating center distance.

How INSCO measures it

INSCO's environmentally controlled inspection lab runs four M&M analytical gear analyzers that compare actual tooth geometry to computer models to within one micron, validating both AGMA and European DIN quality levels. A Zeiss Contura G2 CMM handles dimensional features and gear blanks, and Vari-Roll checkers provide composite inspection. Results are stored electronically, and the shipment documentation package can include analytical charts, heat-treat certification, material analysis, and dynamic balance results as required, giving you the dimensional traceability that medical, defense, and aerospace supply chains demand.