Novel Approach for Drilling Exotic Engineering Materials

Inconel 718 is a Ni-Cr alloy which is used as drill collars in oil and gas industry. These drill collars for deep-water oil exploration have several deep holes which serve as conduits for power supply, data communication and remote monitoring & control with sensors and embedded electronics. Gundrilling is one of the machining processes which is widely employed for small deep holes due to its successful applications on several materials like Al alloys, cast irons and alloy steels. However, gundrilling of Inconel 718 has not been well established owing to failure to achieve straightness deviation of 1 mm/1000 mm and rapid degradation of the carbide tips. This is due to the work hardening effect of extremely tough Inconel 718. To overcome aforesaid problems, non-contact machining process like EDM has been increasingly attempted. Although EDM has been developed over the years, the MRR is very low. Hence, there is a need to investigate the feasibility of new machining process to fabricate deep holes in Inconel 718. In this presentation, a novel hybrid electrical discharge and arc machining (HEDAM)-Gundrilling process has been discussed to address aforesaid issues in deep hole drilling of Inconel 718.