Angular Movement Ratio Planning of the Rotary Axes for Shrouded Blisks Multi-Axis EDM

Compared to traditional machining approaches, multi-axis EDM has its unique advantages in machining components with complex structures made of difficult-to-cut materials, such as shrouded blisks. The manufacturing process of such complex parts involves both synchronized movements of both linear axes and rotary axes. Due to the geometrical difference between the linear and rotary axes, improper resultant velocity which is the combination of each individual axes, is likely to cause inconsistent discharge gaps. In most multi-axis CNC systems for EDM, angular movement ratio is kept to be constant, which may result in an instable discharge status. In order to ensure the machining stability, this paper proposes an angular movement ratio planning method. In this method, CAD models of both electrode and shrouded blisk will be taken into account. For each rotary axis, a parameter is used to represent the angular movement ratio. The ratios help to obtain a single-axis motion constant discharge gap and weighted average movement ratio algorithm can reduce the feedrate fluctuation of synchronized movements.