Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

Abstract

In this study, the breakdown voltage behavior in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V (TC4) in the deionized water is investigated. Firstly, the electric field distortion caused by impurity particles including TC4 or brass metal and bubbles is investigated. And then the breakdown voltage model of TC4 machined by LS-WEDM is established and the experimental verification result indicates that the model predicting results conforms to the actual processing and could be well follow experimental results. Second, the influence of breakdown voltage on surface roughness and kerf width has been revealed, it can be found that the kerf width decreases, and the surface roughness increases as breakdown voltage increased. Besides, the voids become bigger and the surface cracks become deeper and wider with the breakdown voltage increased based on analysis of experiment results but for microcracks distributed on spherical or irregular attachments are not influenced by breakdown voltage due to their randomness. Meanwhile, the transparent bubbles of diameter of 400 nm can be observed near the droplet on the machined surface and its major composing element is oxygen. Finally, internal voids can be found in the joint of deterioration layer and the substrate which will make the combination of deterioration layer and the substrate not strong and easy to fall off.

Study of surface integrity and machining performance during main/rough cut and trim/finish cut mode of WEDM on Ti–6Al–4V: effects of wire material

“…Altug et al [25] applied different heat treatment processes to alter microstructure, mechanical and conductivity properties of Ti-6Al-4V and investigated effects of such heat treatment on machinability during WEDM process. Gong et al [18] observed reduced kerf width and inferior surface finish due to increased breakdown voltage during low-speed WEDM of Ti-6Al-4V in distilled water (as dielectric). Bigger-sized voids and intense surface cracks (deep and wide) were also obtained with an increase in breakdown voltage.…”

“…The WEDM parameters to be employed for multi-cut strategy are based on capabilities of the machine/set-up as well as past experience. According to Gong et al [18,19], poor thermal conductivity and plasticity of Ti-6Al-4V often cause wire rapture due to evolution of high machining temperature. Therefore, machining parameters of multi-cuts with wire offsets are modified to mitigate possibility of wire rapture and to ensure a favourable machining operation.…”

Optimization of a Fuze MEMS Setback Arming Device Based on the EDM Process

“…Therefore, through technology research, this paper explores a high-precision and low-cost fabrication process of a MEMS S&A device: low-speed wire electrical discharge machining (EDM). As a flexible noncontact machining technology with strong advantages involving material selection [39], [40], the EDM process has unique advantages in micropart forming by wire electrode processing and nonmacro force processing [41]- [43]. By using the combined electrode fixture applied in EDM, multiple electrodes can work at the same time, which greatly improves the processing efficiency, and the machined parts have good consistency.…”

A progress review in wire electrical discharge machining process

“…Sarkar et al [34] studied the influence of pulse-on time, pulse-off time, peak current, wire tension, servo voltage, and dielectric flushing pressure on γ titanium aluminide alloy and stated that as the parameters were varied, the increase in cutting speed resulted in an increased surface roughness of the machined component. Gong et al [49] did an experimental study on the influence of break down voltage on kerf and surface roughness of a machined component. Authors stated that increase in the breakdown voltage magnitude would decrease kerf width and increase surface roughness.…”