Tool Path Planning for Near-Dry EDM Milling With Lead Angle on Curved Surfaces

This research investigates the strategy to achieve high material removal rate in tool path planning for the near-dry electrical discharge machining (EDM) milling process using tubular electrode with a lead angle. The proposed strategy to prevent leakage of dielectric mist from the tubular electrode is different from the conventional end milling process due to the difference in material removal mechanism. Tool positions and orientations to engage the electrode into workpiece, machining of workpiece edge, minimum lead angle to machine a curved surface, and minimum and maximum path interval to prevent the mist leakage are derived. Experiments are conducted to validate the model prediction of path planning. Experimental results show plunge method has the highest material removal rate for engaging method, and electrode hole must be located within the workpiece surface when edge of workpiece is machined. For curvature machining, the proposed path planning strategy yields higher material removal rate compared with that from the conventional strategy, which only avoids gouging. This study also reveals that, due to the tool wear and crowning of electrode tip, it is difficult to accurately determine the minimum path interval which will cause the mist leakage.