Multi-objective optimization for the machining performance during ultrasonic vibration-assisted helical grinding hole of thin-walled CF/BMI composite laminates

In this paper, a helical machining method using ultrasonic vibration in association with a hollow grinding wheel, was proposed for hole-making in carbon fiber/bismaleimide (CF/BMI) composite laminates. Comparative studies between ultrasonic vibration-assisted helical grinding (UVHG) and conventional helical grinding (CHG) were carried out. The effects of machining parameters on the output characteristics (cutting force, hole-wall surface roughness, and exit defect) were investigated. The findings indicated that the thrust force and circumferential resultant force of UVHG were reduced by 9.3–55.9% and 15.4–24.7%, respectively. Meanwhile, the UVHG method had an effective impact on surface roughness reduction, and exit defect suppression. The machining parameter optimization model was developed with the objectives of enhancing efficiency while minimizing surface roughness and exit defects. NSGA-II was created to address the multi-objective optimization problem, and the optimal parameter solutions were obtained. Via confirmation tests, the predictions of the optimization model were validated as realistic. The significance of this study lies in the comparative analysis and multi-objective optimization with varied machining parameters, which emphasizes the advanced UVHG method using hollow grinding wheels in the thin-walled laminates hole-making process.