A macroscopic mechanical model of wire electrode deflection considering temperature increment in MS-WEDM process

•A macroscopic mechanical model of wire deflection is developed in the area near the guide wheel of MS-WEDM due to the wire moving on guide wheels.•A novel approach, fourth-order function fitting, is implemented to describe the wire trajectory between the two guide wheels of MS-WEDM.•Two macroscopic mechanical models are established in the non-discharge area and the discharging area considering the temperature increment by the new method.•From the confirmation experiment and comparison with other’models, it can be concluded that two macroscopic mechanical models of wire deflection are reliable and feasible.

In medium-speed wire electrical discharge machining (MS-WEDM), wire in the area near the guide wheel and between the two guide wheels obviously form the wire bending deformation due to wire tension, electrostatic force, electrodynamics force, hydrodynamic force, temperature increment, etc. Besides, the wire deflection would have a direct influence on the machining accuracy, productivity and stability. In this paper, first of all, main causes of wire electrode deformation are proposed to better understand its fundamental mechanism. Second, two macroscopic mechanical models of wire deflection are developed in the area near the guide wheel and between the two guide wheels considering temperature increment and wire vibration in machining 20 mm-thickness workpiece process, respectively. Moreover, the numerical solution of deflection in the area near the guide wheel and the theoretical solution of deflection between the two guide wheels has been worked out. Then, the analysis of the variation trend of wire deflection and the influences of wire deflection on the machining process have been conducted. Eventually, from the confirmation experiment and comparison with other researchers’ models, it has been proved that the macroscopic mechanical models of wire deflection in MS-WEDM process are reasonable and reliable. In addition, according to macroscopic mechanical models, some of the practical approaches of reducing wire deflection have been proposed to improve machining accuracy, and these high-precision models can be applied into NC system to set a compensation for wire deflection in the future.