Micro-lubrication-assisted drilling of SLM Hastelloy-X and Ti-6Al-4V

Minimum-quantity lubrication (MQL) was evaluated for drilling Hastelloy-X and Ti-6Al-4V produced by selective laser melting (SLM). A full-factorial design combined three cutting speeds (15–25 m/min), three feeds (0.05–0.08 mm/rev), and dry or MQL conditions. Duplicate nonconsecutive runs covered 36 combinations and 144 holes; each fresh 8 mm FIREX-coated carbide drill produced two holes. Results were summarized as means and sample standard deviations. Hastelloy-X exhibited greater flank wear, thrust force, and specific cutting energy (SCE), whereas Ti-6Al-4V generally produced rougher holes. MQL generally reduced wear and improved hole finish in both alloys and consistently lowered thrust and SCE in Hastelloy-X. Its effect on titanium thrust depended on speed, with the clearest benefit at 25 m/min. Increasing feed raised thrust and wear, while higher speeds and feeds generally reduced SCE. MQL shows promise for drilling functional holes in SLM nickel and titanium alloys.