High-performance milling of Ti-6Al-4V through rotary ultrasonic elliptical milling with anticlockwise elliptical vibration

Ultrasonic elliptical vibration cutting (UEVC) with clockwise elliptical vibration has made notable achievements in precision machining; however, its critical cutting speed limits its application to low-speed machining tasks. Meanwhile, rotary ultrasonic elliptical machining (RUEM) with clockwise elliptical vibration has been validated as an effective high-speed cutting technology. Unfortunately, conventional RUEM leads to increased surface roughness. To address this issue and enhance machining quality, we propose a novel RUEM method employing an anticlockwise vibration direction, called anticlockwise rotary ultrasonic elliptical machining (ARUEM). The mechanisms of surface formation and subsurface strengthening for ARUEM are analyzed. Experimental validations were performed on Ti-6Al-4V alloy, revealing that ARUEM achieved substantially lower ridge heights and up to a 50% reduction in surface roughness compared to conventional RUEM. Additionally, relative to conventional milling, ARUEM resulted in up to 122.6% thicker plastic deformation layers, 53.4% higher surface residual compressive stress, and 19.3% greater surface micro-hardness. This study showcases a promising method for high-performance milling of Ti-6Al-4V, offers new insights into RUEM by examining the influence of vibration direction, and enhances understanding of surface formation and subsurface strengthening in the ARUEM method.