Multi-objective optimization of geometric accuracy in multi-angle inclined air-film holes processed by water jet guided laser

Water jet guided laser (WJGL) is a key technology for machining air-film holes in turbine blades for aircraft engines. Most existing optimization studies are limited to vertical holes or a single inclined angle, making it difficult to meet the high-precision manufacturing requirements for inclined air-film holes with multiple inclined angles. This paper employed a multi-objective optimization method combining RSM-Kriging-NSGA-II to conduct a study on the co-optimization of the geometric accuracy of inclined air-film holes. Using laser power, argon gas flow rate, scanning speed, and inclined angle as input variables, and hole entrance circularity, exit circularity, and taper as geometric accuracy evaluation metrics, experimental data were obtained through RSM; Data augmentation was achieved using quadratic polynomial regression combined with Latin hypercube sampling (LHS) to construct a high-precision Kriging surrogate model, revealing the mechanisms and coupling patterns of parameter effects on geometric accuracy; Pareto front solution set was obtained using NSGA-II. The results show that the prediction accuracy of the augmented Kriging model is significantly superior to that of the original Kriging and RSM models. Under optimized process parameters, the relative error of the model predictions is less than 10%. Compared to the original process, entrance circularity improved by 3.37%, exit circularity by 1.5%, taper was reduced by 45.5%, and the micro-hole contour was regular, with no obvious thermal damage or residue accumulation. This method enables multi-objective optimization of geometric accuracy for inclined holes ranging from 0 to 60°, providing effective technical support for the high-precision machining of inclined air-film holes in aircraft engines.