Overcoming the myriad challenges in the high-speed machining of Inconel 718, especially for deep-hole drilling (DHD), has been a long-standing area of research for several manufacturers and researchers. Owning to the difficult-to-machine characteristics of Inconel 718, the traditional carbide-tipped gun drills often get worn at an accelerated pace and require repetitive re-sharpening or replacement. This lowers productivity and increases costs. Furthermore, it is also a challenging task to meet the stringent hole-straightness requirement of 1/1000 mm for DHD of such difficult-to-machine materials, especially using those carbide gun drills. Hence, this study presents a development of polycrystalline cubic boron nitride (PCBN)-tipped gun drill to address the rapid tool degradation and poor hole-straightness issues. The developed PCBN-tipped gun drill has a layer of PCBN on its cutting tip and bearing pads. Several gun drilling tests on Inconel 718 have been performed at high drilling speed conditions to assess the performance of developed gun drill. In contrast to traditional carbide-tipped gun drills, the developed PCBN-tipped gun drill has the capability of not only performing in the higher cutting speeds but also reducing drilling forces, drilling torques, and tool wear. Furthermore, the surface quality of drilled holes is also much better than those drilled by traditional carbide gun drills. With these results, it further validates the credibility of the developed PCBN gun drill in enhancing the deep-hole drilling process with high throughput productivity and superior quality of drilled holes, especially for difficult-to-machine materials.

克服Inconel 718的高速加工（尤其是深孔钻削（DHD））中的众多挑战，已成为许多制造商和研究人员长期研究的领域。由于Inconel 718难以加工的特性，传统的硬质合金枪钻通常会以较快的速度磨损，并且需要重复重新磨削或更换。这降低了生产率并增加了成本。此外，对于这种难以加工的材料，尤其是使用那些硬质合金枪钻的DHD，要满足1/1000 mm的严格的孔直度要求也是一项艰巨的任务。因此，本研究提出了一种多晶立方氮化硼（PCBN）尖头的枪钻，以解决刀具快速退化和孔直度差的问题。已开发的带有PCBN的枪钻在其切削刃和轴承垫上有一层PCBN。已经在高钻孔速度条件下对Inconel 718进行了几次枪钻测试，以评估已开发的枪钻的性能。与传统的带硬质合金的枪钻相比，开发的带PCBN的枪钻不仅具有更高的切削速度，而且还具有降低钻孔力，钻孔扭矩和工具磨损的能力。此外，钻孔的表面质量也比传统硬质合金枪钻的表面质量好得多。凭借这些结果，它进一步验证了开发的PCBN枪钻在增强深孔钻探过程方面的信誉，具有高生产率，高钻孔质量，特别是对于难加工的材料。