Methods to Measure Wire Deflection in Wire EDM Machining

Abstract

It is well kown that the wire electrode is flexible and will lead to a big lag in wire EDM machining, especially in the middle area of the work-piece. Methods to measure the wire deflection when it passes through the work-piece are studied in this paper. It is found that there is discharge spark first at the upper and lower parts of the wire when it cuts to the edge of the work-piece. The discharge spark appears at the middle of the work-piece a few seconds later. Based on this result, a method coined Camera Picture Analysis (CPA) is proposed to estimate the wire deflection. Another method of cross section measurement by the CCD is proposed to make a cross reference with the CPA method. By applying these two methods, the wire deflection models can be established, and used for the corner cut control of wire-cut EDM to improve accuracy of the machined parts.