Modelling and experimental investigation of flat surface achieved by large rectangular electrochemical jet milling

Electrochemical jet milling (EJM), an important non-traditional machining technique, has been identified as a promising method for fabricating components on a wide range of conductive materials. However, EJM faces great challenges in fabricating uniform surfaces because the optimal step-over between two adjacent trajectories is difficult to ascertain. In the past, the optimal step-over has been determined roughly through a large number of experiments, which was inaccurate, time-consuming, and expensive. In this study, a mathematical model was innovatively proposed to predict the relationship between uniformity and step-over prior to the experiment. This method can predict features with good accuracy and low computational costs. A large cathode tool was used in the EJM to fabricate a large flat surface. The optimal step-over of different parameters for realizing flat surface was firstly proposed and the unique processing mark at optimal step-over was firstly revealed. The results indicate that the optimal step-over between two adjacent trajectories is the same as the width of the nozzle orifice. The processing mark of the flat surface at the optimal step-over exhibits a “valley–peak” shape. Moreover, the uniformity of the machined surface can be improved by utilising a higher cathode travel rate. The experimental results are in good agreement with the analytical model. In addition, a large flat surface with dimensions of 90 × 90 mm was successfully fabricated.