Step-dependent machining uncertainty modeling for the process route and application in the machining of the ring-gear

This paper proposes a step-dependent machining uncertainty modeling method for the process routes. With the between-step interaction, the process route integrity is accurately interpreted and all error sources in the production environment are involved in, including the workpiece positioning surface, machine positioning surface, cutter kinetics, workpiece kinetics, clamping force, cutting force, environmental factors, residual stress distortion, heat treatment distortion, and coating/plating variations. The machining uncertainty model shows that the machining uncertainty consists of both regenerated and inherited uncertainties. The proposed modeling method can evaluate a process route in terms of its error source impact on workpiece accuracy. A herringbone gear ring is used to demonstrate its effectiveness as a case study, where an uncertainty model is developed for the full process route, and the process route is assessed before the costly process trial. The process number is reduced from 18 to 15 without affecting the final workpiece accuracy. The experiment shows a good agreement with the uncertainty model results.