Design method and experimental study of three-step method for electrochemical machining of blisks

To ensure the dimensional accuracy of the final blade profile, it is necessary for precision Electrochemical Machining (ECM) of blade profile to come into an equilibrium state. However, after Electrochemical Trepanning (ECTr), the cascade channel of the blisk is narrow, and the blank allowance distribution is uneven, making it difficult for the precision ECM to become balanced. In blisk production, the two-step method cannot make precision ECM enter equilibrium for some blisk types. A three-step processing method is proposed to overcome this problem. The three-step method adds Electrochemical Homogenizing Machining (ECHM) between the ECTr and precision ECM steps so that the blank allowance can be homogenized quickly without unduly affecting the minimum allowance. Comparative machining experiments of the two- and three-step methods were performed to verify the improvement to blade machining accuracy. The processing results show that the contour parameters of the blade after the three-step method implementation are much better. The allowance difference of the concave (convex) side decreased by 70.5% (65%). In addition, the current in the three-step method is stable at 110 A at the end of precision ECM, verifying successfully entering the equilibrium state.