Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Influence of process variables on geometrical deviations in WEDM trim cuts
Submission Author:
Maria Vitoria Sikora , SC , Brazil
Co-Authors:
Maria Vitoria Sikora, Paulo Matheus Borges Esteves, Konrad Wegener, Michal Kuffa
Presenter: Maria Vitoria Sikora
doi://10.26678/ABCM.COBEM2021.COB2021-0800
Abstract
Wire electrical discharge machining (WEDM) is a non-conventional machining method capable of cutting complex shapes on hard materials. The die manufacturing and aerospace sectors, main applications of WEDM, require high workpiece precision. In WEDM the kerf (cutting width) might not be constant along the wire which may cause deviations on the workpiece. The kerf value is affected by tool erosion and inhomogeneous cutting conditions like flushing, concentration of debris, wire vibration, cutting parameters, etc. When comparing the top and bottom of the workpiece, a deviation labeled conicity may appear and can compromise accuracy. Nevertheless, the causes of this difference are yet unidentified. Given the importance of workpiece precision in this specific process, it is essential to explore which variables influence this geometrical deviation. Therefore, this study aims to investigate the influence of individual process variables on the conicity produced by WEDM trim cuts. Using brass CuZn37 (DIN CW508L) wire as the tool and AISI D2 steel as workpiece material, a design of experiments (DOE) is elaborated varying: flushing conditions, unwinding speed, pulse energy, piece height and pulse-off time while tracking the cutting duration, total number of discharges and short circuits. The conicity of the produced pieces is measured with a micrometer caliper. A variable to represent the physical aspect of the wire wear is created using the calculated pulse frequency, piece height, unwinding speed and pulse energy. The results are interpreted with an analysis of variance (ANOVA) and a graphical comparison. The flushing conditions, cutting duration, and pulse-off time were shown not to be statistically relevant. The most relevant parameters were the unwinding speed, pulse energy and wire wear variable. This result suggests that the conicity phenomenon is caused rather by the tool erosion than by cutting conditions.
Keywords
WEDM, geometrical deviations, wire wear, tool erosion
