Evaluation of profile accuracy and surface integrity for Inconel 718 blade machined by ultrasonic peening milling

Abstract

The blade is the most important component of the aero-engine in an aircraft. Aero-engine blades comprise thin-walled structures with complex curvatures, which are processed and manufactured by difficult-to-cut materials, such as Inconel 718. The blade profile accuracy and surface integrity are difficult to achieve using the conventional milling (CM) process only, as it directly affects the overall performance and reliability of the aero-engine. In this study, the deformation theory of thin-walled blades during the milling process was systematically analyzed, and the effectiveness of the ultrasonic peening milling (UPM) process in controlling the profile accuracy and surface integrity of Inconel 718 blades was evaluated. This study employed a simplified model of an Inconel 718 blade machined by UPM and CM and compared the milling forces under the milling processes. The profile accuracy (with straight or curved geometry) and surface integrity of the blades are measured and evaluated after the milling tests. The validation results show that UPM has significant advantages in terms of reducing milling forces, increasing blade profile accuracy, and improving the surface integrity during the milling process. This study affords a new process to enhance milling profile accuracy and achieve surface integrity control of Inconel 718 blades.