Face-gear meshing with a involute helical pinion was studied.Tooth surface equations were gained through accurate computation.Computer simulation was performed to form the numerical tooth surface.Based on the different conversion coordinate systems

the misalignment of the face-gear system was simulated and was decomposed into three kind of decoupled assemblerror.When one kind of assemble error was existed and others were zero

the location of contact trace was calculated accurately and simulated by computer program on the tooth surface.