Calculate radial or axial runout from inspection readings by comparing maximum and minimum indicator positions, then check the total indicator reading against a specified limit.
| Item | Value | Meaning |
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Runout is the variation observed by an indicator when a component or feature is rotated relative to a specified datum axis or reference. It is commonly checked on shafts, journals, turned diameters, bores and rotating faces.
Runout inspection can identify unwanted eccentricity, angular variation, machining errors, setup problems and other geometric variation that affects rotating components.
Total indicator reading, commonly abbreviated TIR, is the difference between the maximum and minimum indicator readings observed during the inspection rotation.
Because the calculation uses a difference, the readings can be positive, negative or zero. Their absolute position relative to zero does not affect the calculated TIR.
Radial runout is commonly checked on cylindrical surfaces as a component rotates around its datum axis. An indicator contacts the surface and the variation between the highest and lowest readings is recorded.
Axial runout is commonly evaluated on a face as the component rotates around its datum axis. The indicator measures movement in the axial direction during rotation.
Tolerance utilization shows how much of the specified runout allowance has been consumed by the measured TIR.
For example, a TIR of 0.05 mm against a 0.10 mm limit uses 50% of the specified runout allowance.
Remaining tolerance is the difference between the specified runout limit and the measured TIR.
A positive value means the measured runout remains inside the entered numerical limit. Zero means it is exactly at the limit. A negative value means the limit has been exceeded.
Runout and concentricity are related but different geometric characteristics. Runout is evaluated during rotation relative to a datum axis and can be measured directly with an indicator.
Concentricity concerns the relationship between theoretical centers or axes. A component can therefore have a particular concentricity condition while producing a different runout result depending on form and orientation.
Circularity controls the form of an individual circular feature. Runout evaluates variation relative to a datum axis during rotation.
A surface can have good circular form but still show runout if its axis is displaced or its orientation is incorrect relative to the datum.
This calculator determines total indicator reading from the inspection readings you provide. It does not establish the correct datum system, inspection setup, tolerance zone or governing geometric-tolerancing requirement.
Actual component acceptance should follow the applicable engineering drawing, inspection plan, measurement procedure and calibrated equipment requirements.
What is TIR? TIR is total indicator reading, calculated as the maximum indicator reading minus the minimum indicator reading.
Can readings be negative? Yes. Negative indicator readings are valid inputs because TIR depends on the difference between the maximum and minimum readings.
What is radial runout? Radial runout evaluates variation of a cylindrical surface relative to a rotating datum axis.
What is axial runout? Axial runout evaluates variation of a face in the axial direction during rotation around a datum axis.
How is remaining tolerance calculated? Remaining tolerance equals the specified runout limit minus the calculated TIR.
What does 100% tolerance utilization mean? The calculated TIR is exactly equal to the specified runout limit.
Does PASS certify the component? No. It only confirms that the entered TIR is numerically within the entered limit.