It may not be widely recognized, that most of the inspection data supplied by inspection equipment following
the practices ofAGMAStandard 201 5 and similar standards, are not ofElemental accuracy deviations but of
some form of Composite deviations. This paper demonstrates the validity of this “Composite” label by first
defining the nature ofatrue Elemental deviation and then, byreferring to earlierliterature, demonstrating how
the common inspection practices for Involute, Lead (on helical gears), Pitch, and in some cases, Total
Accumulated Pitch, constitute Composite measurements. The paper further explains how such
measurements often obscure the true nature of the individual deviations. It also contains suggestions as to
somelikelysourceofthedeviation in variousgearmanufacturing processesand howthatdeviation mayaffect
gear performance. It further raises the question of the likely inconsistencies of some of these inspection
results and of inappropriate judgments of gear quality, even to the point of the rejection of otherwise
satisfactory gears. Finally, there are proposals for modifications to inspection software, possibly to some
inspection routines, all to extending the benefits of the basic Elemental inspection process.
AGMA 08FTM15-2008 pdf download
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