Investigation on performance characteristics of micro-EDM dressing for the fabrication of micro-rod(s) on Ti-6Al-7Nb biomedical material

Abstract

The performance characteristics of micro-EDM dressing were investigated based on some real-time and offline responses for the fabrication of micro-rod(s) on a novel Ti-6Al-7Nb biomedical material. These characteristics evaluated along the micro-rod length at three different discharge energy settings were analyzed by monitoring the discharge gap condition captured through an in house developed pulse-discriminating system (PD). The experimental results show that the normal pulse was more (∼90%) in the low energy setting (E₁). In contrast, arcing was more (∼28%) in the high energy setting (E₃). Pulse frequency was found more (∼60 $N_c/\mathrm{s}$) in E₁. However, due to an increase in the ‘idle’ time, it significantly decreased (∼25$\mathrm{ }{N}_c/\mathrm{s}$) along the machining length. $\text{Material removal rate},$ however, was found more (∼5.7 × 10³, µm³/s) in E₃. The specific energy was found very high (∼9 MJ/mm³) in E₁ since the process spent additional energy to remove the re-solidified molten metal. The $\text{tool wear ratio}$ was, on the other hand, found very high (∼2.1) in E₁ due to prolonged exposure to discharges and experiencing higher total discharge energy by the work-tool interface. E₃ was found more suitable for fabricating dimensionally accurate micro-rod(s) on this material because of less tool wear.

Keywords:

• Micro-EDM dressing
• offline responses
• pulse-discriminating system
• real-time responses
• Ti-6Al-7Nb