The machining principle of Gleason CONIFACE grinding method for face gear is developed.The shape and tooth surface equation of grinding wheel are deduced.The tooth surface equation of CONIFACE grinding method for face gear is obtained

based on theories of differential geometry and gear mesh.The error and the law of the error of CONIFACE grinding method are analyzed.The results show that the tooth thickness adopting the machining method is narrower than the gear thickness which is available in the Apache helicopter plane as NASA reported.The machining error is minimum at the middle point of the tooth width and increases gradually to both ends

which is similar to the effects that the cylindrical gear take drum shape modification

and the drum quantity error can be controlled by changing the cone angle of the wheel cutter and the radius of the grinding wheel.