Assessment of vibration-assisted micro-EDM dressing process-stability by monitoring and analyzing debris evacuation during Ti-6Al-7Nb machining

摘要

Despite several benefits, the micro-EDM dressing has not achieved widespread acceptance in the microfabrication industries due to its low process-stability, which resulted in low material removal rate (MRR), surface finish, and dimensional accuracy. The vibration of the tool-plate showed significant improvements in this regard. Additionally, understanding the process-stability of micro-EDM dressing under vibration in terms of debris evacuation in real-time will surely help to utilize the process better, which lacks recognition to date. In this regard, the present work used a high-speed camera and image processing technique to monitor and analyze the debris evacuation while machining an emerging Ti-6Al-7Nb biomedical material. The process-stability was assessed by the percentage of normal and arcing pulses, and the average workpiece retraction height was monitored in real-time. Furthermore, the stability results were used to explain its performance measures, mainly MRR, area surface roughness (Sa) and dimensional accuracy. The experimental results showed an increased debris number (- 3-38 times) and average velocity (- 1.3-2.2 times) in the focused window under the tool-plate vibration compared to no vibration. The results also showed an increased percentage of normal pulses (- 1.1 times) and a decreased average workpiece retraction height (- 1.5 times) with an increased vibration amplitude from 0.65 (a1) to 4.41 mu m (a5), which were also as per the debris evacuation results. However, despite having a higher average debris velocity, the higher vibration frequency didn't offer a superior inter-electrode gap condition, as verified through the stability results. The process's performance results under different vibration frequencies were also found as per the stability results.