Dimensional control of turbine blades via RSM-based process parameter optimization in investment casting

• Withdrawal rate is the dominant factor influencing dimensional deformation in investment casting of DD6 turbine blades. • Shell temperature exhibits a pronounced U-shaped nonlinear effect on deformation, with significant interactions among process parameters. • The response surface model achieves high predictive accuracy (R²=0.978, RMSE=0.0026 mm) and generalizes well beyond the simulated dataset. • Optimized process parameters reduce maximum deformation by 5.74% compared to conventional orthogonal design, from 0.2021 mm to 0.1905 mm.