During ausform finishing process of hardened gears

there is plastic displacement of metal on the tooth surface and the distortion of tooth profile .If the rolling dies are not preciously designed or the machining operation is not properly implemented

there is an influence on the profile accuracy

noise and service life of the workpiece gears. Many causes are found to contribute to the profile error of teeth

but this paper only focuses on

in engagement theory

the changes of slip factor on the surface of the workpiece gear

which is in double-flank engagement with tool gears without backlash. Then the equations of slip factor for driven side and follower slide of a tooth of the workpiece are elaborated separately. On the basis of this

the influence of the changes of slip factor on profile error is analyzed. This research proves to be helpful to analyze completely machining error in ausform finishing

and it provides an important parameter in profile design of rolling dies.