Gear testing technology is the key factor to improve the gear manufacturing quality

comparing with the traditional gear accuracy index

the accuracy of the whole tooth surface can entirely reflect the processing quality of the gear. The tooth surface deviation is measured by gear measuring center and fitted by bi- cubic B- spline

the tooth surface deviation is separated into first- order and second- order deviation by using the least squares method

which reflect the inclination of the tooth surface deviation and the bending degree. For the different gear processes

the machining error sources are analyzed through the first- order and second- order deviation

that can guide the gear machining process.