On the Influence of Wire-lag on the WEDM of Low-radius Free-form Geometries

The wire electro-discharge machining (WEDM) is a widely-used machining process suitable to achieve the increasingly demanding precision requirements imposed by industry. Nevertheless, the use of conventional WEDM machines under some complex geometrical conditions makes sometimes difficult to fulfill these requirements, which is a topic of interest in the manufacturing of high-added aerospace components. Different effects overlap to damage precision when cutting these geometries. In this work a study on the causes of dimensional deviations in small-radius circles has been carried out. The study focuses on two effects: wire-lag and concavity shape on the workpiece produced by electrostatic and electromagnetic forces. At the sight of the results, a classification of radius is proposed taking into consideration the main cause of lack of accuracy. It has been found that wire-lag effect must only be considered when machining circles of radius smaller than a certain value that can be established by simulations. For the conditions of the tests of this study, this value is 3 mm. It can also be stated that concavity effect is a function of machined radius.