High-speed machining of additively manufactured Inconel 718 using hybrid cryogenic cooling methods

Although additive manufacturing technologies offer manufacturing highly complex parts, the manufactured parts generally have poor surface quality. Owing to low machinability of hard-to-cut additively manufactured parts, a synergistic approach involving advantages of additive manufacturing and machining processes is needed. This study investigates high-speed machining of additively manufactured nickel alloys using hybrid cryogenic cooling methods. For the first time, a comprehensive study has been presented to compare the synergistic effect of hybrid cooling and lubrication strategies in high-speed milling of additively manufactured parts produced with powder bed fusion and directed energy deposition. The results indicate strong dependency of machinability on additive manufacturing methods and post-treatment strategy used. Hybrid methods make high-speed machining of additively manufactured parts possible, resulting in longer tool life and better surface finish. The cooling plays more significant role on tool life than lubrication. However, it was found that the hybrid cooling methods balanced heat removal and lubrication effects.