Drilling of micro-cooling holes in turbine blades on hard material like Inconel 625 is one of the noteworthy applications of micro-drilling. An experimental investigation on the hole quality assessment and drill bit tool life while micro-drilling of Inconel 625 is not explored in detail. This paper presents the experimental study and multi-response optimization of test parameters of Inconel 625 in micro-drilling conditions using desirability approach. Test parameters are micro-drill diameter, spindle speed, and feed rate. The micro-drilling test, based on the Taguchi L₂₇ design, is performed on a 2-mm plate thickness of Inconel 625 with uncoated micro-drill. After each drilling test, the hole properties including hole diameter, circularity error, overcut, taper ratio, cylindricity and hole damage factor are measured, and the results are examined. In addition to that, the number of micro-holes that can be drilled is analysed to observe the lifelong tool performance on hole quality assessment. As a result, the number of holes drilled before tool breakage is 25 in magnitude. The deviation in hole diameter, cylindricity, circularity error, roundness, overcut, taper ratio, and hole damage factor obtained is increased to 5.5%, 87.2%, 50.5%, 5.7%, 77.4%, 20% and 5.4% from 1st hole to 25th hole at an optimal level of high tool diameter, low speed, and high feed rate. The most significant drilling parameters for the above-studied response factor are tool diameter and spindle speed. From the results, the 0.8 mm is the most suitable tool diameter for hole quality achievements and productivity in practical micro-drilling applications.

在涡轮机叶片上的硬质材料（例如Inconel 625）上钻微冷却孔是微钻的重要应用之一。没有详细探讨在Inconel 625的微钻孔中进行孔质量评估和钻头刀具寿命的实验研究。本文采用期望方法，介绍了Inconel 625在微钻孔条件下测试参数的实验研究和多响应优化。测试参数是微钻直径，主轴转速和进给速度。基于田口L ₂₇的微钻测试设计是在2毫米厚的Inconel 625平板上使用未涂覆的微钻进行的。每次钻孔测试后，都要测量孔的性质，包括孔直径，圆度误差，超切，锥度比，圆柱度和孔损伤系数，并检查结果。除此之外，还分析了可钻的微孔数量，以观察终身质量的工具对孔质量的评估。结果，在工具损坏之前钻出的孔的数量级为25。从第一个孔到第一个孔，孔直径，圆柱度，圆度误差，圆度，超切，锥度比和孔损坏系数的偏差分别增加到5.5％，87.2％，50.5％，5.7％，77.4％，20％和5.4％。第25孔以高刀具直径，低速度和高进给率的最佳水平进行。对于上述响应因子而言，最重要的钻孔参数是刀具直径和主轴转速。从结果可以看出，0.8 mm是在实际微钻孔应用中实现孔质量和生产率的最合适的工具直径。