Rotary ultrasonic elliptical machining for side milling of CFRP: Tool performance and surface integrity

•A CFRP side milling method by rotary elliptical ultrasonic machining (REUM) is proposed.•The factors for the cutting force reduction in RUEM is revealed.•The tool clogging as a typical tool wear mode in conventional grinding (CG) is avoided in RUEM.•The machined surface quality is greatly modified in RUEM in comparison of that in CG. The rotary ultrasonic elliptical machining (RUEM) has been recognized as a new effective process to machining circular holes on CFRP materials. In CFRP face machining, the application of grinding tools is restricted for the tool clogging and the machined surface integrity. In this paper, we proposed a novel approach to extend the RUEM process to side milling of CFRP for the first time, which kept the effect of elliptical vibration in RUEM. The experiment apparatus was developed, and the preliminary experiments were designed and conducted, with comparison to conventional grinding (CG). The experimental results showed that when the elliptical vibration was applied in RUEM, a superior cutting process can be obtained compared with that in CG, including providing reduced cutting forces (2–43% decrement), an extended tool life (1.98 times), and improved surface integrity due to the intermittent material removal mechanism and the excellent chip removal conditions achieved in RUEM. It was concluded that the RUEM process is suitable to mill flat surface on CFRP composites.