Stability research on step milling of GH4169G blisk

Finite element analysis was applied to solve the problem of instability during milling blisk blade made of high strength superalloy GH4169G. Both methods of milling along the major diameter and axial direction were studied to analyze the machining stability. The effects of both the step milling and general symmetry milling on the machining stability were analyzed in the milling process of the blisk blade. Results show that the limit cutting depth in the stability lobe is less than the probable maximum cutting depth, the machining parameters such as the spindle speed and cutting depth can be chosen in a small range when the blade is cut by layers along the major diameter. The limit cutting depth in the stability lobe is larger than the probable maximum cutting depth when the blade is milled axially by layers. The rigidity of the blisk blade is improved by the step milling method. The maximum deformation of blade is 60% lower than that of the general symmetry milling in the same load. Compared with the general symmetry milling, the step milling method has the higher frequencies at the first six modes and the better stability, and the blades machined can meet the design requirements.