Investigation of the impact of Rehbinder effect, electrical erosion and wire tension on wire breakages during WEDM

Publication date: June 2018 Source:Journal of Materials Processing Technology, Volume 256 Author(s): Alexey A. Fedorov, Alexander I. Blesman, Denis V. Postnikov, Denis A. Polonyankin, Gregory S. Russkikh, Alexander V. Linovsky The paper provides an analysis of the influence of the Rehbinder effect, electrical erosion and wire tension on breakages during wire electrical discharge machining (EDM) of steel 36CrNiMo4 (the analogue of AISI 9840) by the SODICK VZ300L machi. A classification of wire breakages (explicit and implicit) is proposed and the reasons for both breakage types are considered. The methods of optical microscopy, scanning electronic microscopy, fractography, and tensile testing of the wire in the air atmosphere, as well as pure and impure deionised water, are used to demonstrate that the Rehbinder effect and microdamage caused by electro-discharge do not have a substantial influence on implicit brass wire breakages. The experimentally determined average value of the amorphous zone width (8.4 μm) of an eroded wire was used during its stressed-state simulation, resulting from the non-uniformity of the temperature distribution throughout the wire depth. To estimate the influence of thermal stresses on implicit wire breakages, the internal thermal stresses calculation algorithm, based on the generalised Hooke’s law in a differential form and the consideration of stresses caused by thermal wire expansion, is proposed. Considering the wire pre-tension act...
Source: Journal of Materials Processing Technology - Category: Materials Science Source Type: research