Effectiveness of a Resonantly Designed Horn - Workpiece System Design in Ultrasonic Vibration - Assisted Milling

Hard milling of tool steel commonly encounters substantial difficulty in simultaneously achieving a high material removal rate (MRR) and low surface roughness (Ra). In ultrasonic vibration-assisted milling (UVAM), the vibration amplitude A is a highly influential process parameter; however, this amplitude can only be generated when the ultrasonic excitation and transmission system is correctly designed to operate under resonant conditions and remains stable under cutting load. This paper clarifies the relationship between the calculation and design of a resonant ultrasonic horn-workpiece system at 20 kHz and the resulting improvement in material removal rate and surface roughness in UVAM. The results indicate that the calculation and resonant design of the horn-workpiece ultrasonic vibration system at 20 kHz constitute the key enabling factor for the significant enhancement of MRR and Ra. By measuring the vibration amplitude (A) at the end face of the workpiece and calibrating the relationship between vibration amplitude A and workpiece length Lp to reproducibly restore the target vibration amplitude A, a four-factor Box-Behnken experimental design involving A, Vc, Vf, and ae was established. Experimental trials were then carried out for both ultrasonic vibration-assisted milling and conventional milling. The results show that ultrasonic vibration-assisted milling significantly increases the material removal rate while markedly reducing surface roughness compared with conventional milling.