Applying projection method

the involute plastic gear tooth profile deviation is measured.As plastic gear tooth profile is much influenced by mechanical stress and thermal stress in machining

thus causing more tooth profile strain

to reflect precisely the measuring result of plastic gear tooth profile deviation

and confirm the precision level of it

the rotation bias error

rotation division error

aiming indication error and repeating measuring error are appraised by A series uncertainty and B series uncertainty.Trough analysis by the statistic range controlling chart

a same conclusion is reached.Combining single tooth profile deviation measurement with random sampling inspection

the accuracy grade of plastic gear tooth profile deviation is confirmed

which is out of the national standard range of gear tooth profile accuracy grade.Thus

the tested plastic gear by machining is more used in display in laboratory than in industry.