Study of tool trajectory in blisk channel ECM with spiral feeding

Electrochemical machining (ECM) plays an important role in blisk manufacturing. There are two steps in blisk ECM: machining of channels and precise shaping of blade profiles. In channel machining, channels are machined in the workpiece with allowance left to the following process. Therefore, the main aim of channel machining with ECM is to improve the allowance distribution. With this aim, a new ECM method for blisk channels, spiral feeding ECM, is developed in which the cathode feeds from blade tip to hub along with rotation motion around its axis. Through this combined motion, twisted channels are produced in the workpiece. The relationship between feed position and rotation angle is presented in the form of a mathematical model. Experiments with a feed rate of 1 mm/min confirm that spiral feeding ECM is feasible and efficient. Compared with radial ECM, the allowance differences in blank back and blank basin decrease by 32.7% and 33.6%, respectively. The surface roughnesses Ra in blank back, blank basin, and hub are 0.358, 0.308, and 0.102 µm, respectively. Thus, the allowance distribution is improved to be more uniform considerably and the surface quality is relatively high.