An analysis and optimization of the geometrical inaccuracy in WEDM rough corner cutting

Wire electrical discharge machining (WEDM) has occupied an important position in some high-precision and high-performance manufacturing industries due to its capability of accurate and efficient machining parts with varying hardness or complex shapes. However, the high-machining precision and efficiency, especially at rough corner cutting, cannot be satisfied simultaneously because of some phenomena such as wire rupture, deflection, vibration, etc. This paper aims to analyze and reduce the geometrical inaccuracy of rough corner cutting; first of all, the major causes of corner inaccuracy (45°, 90°, and 135° angle) are analyzed in detail. Secondly, an elliptic fitting method is proposed to describe the trajectory of wire electrode center, and the feasibility of model is confirmed by measuring the corner edge of workpiece. Moreover, three sets of Taguchi experiments (L2737) are designed to investigate the main effect and influence trends of control factors on corner error. Eventually, some optimized control factor combinations are sought by generalized non-linear regression model. As a result of confirmatory experiments, more than 50 % decrease of corner error has been achieved at 5 mm/min cutting feedrate (a high-cutting feedrate of the machine tool used in this study) by the optimized control factors combination in rough corner cutting.

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