Fundamental Study of Accuracy of Wire EDM (4th Report)

Improvement of Accuracy of Rough Cut Concave Small Corner R by Over cut-Dwell Method

Abstract

The previous 2nd and 3rd reports described methods by which to improve the accuracy of the convex corner, corner R and large concave corner R on the rough cut of a workpiece, where the wire discharges symmetrically on front surface of the wire. The present paper describes methods by which to improve the accuracy of the concave corner having small radius corner R on the rough cut, where the wire discharges asymmetrically on the wire surface. A new method that combines the dwell operation method with the over cut method is proposed. The procedure and expressions used to calculate these control values based on a wire deflection model are described. In addition, the advantage of high wire tension is discussed. The proposed method was found to be useful for improving the concave corner accuracy and saving machining time.