Rotary ultrasonic surface machining of CFRP composites: Effects of horizontal ultrasonic vibration

Carbon fiber reinforced plastic (CFRP) composites are popular in many industries due to their superior properties. However, many problems, including high cutting forces, high tool wear, high surface roughness, etc., are generated in conventional surface grinding (CSG) processes, due to the carbon fibers' abrasive property as well as the inhomogeneous and anisotropic properties of CFRPs. Rotary ultrasonic surface machining (RUSM) with vertical ultrasonic vibration has been proven to be effective to reduce cutting forces. However, this process produces larger surface roughness than CSG because of vertical ultrasonic vibration. To solve this issue, RUSM with horizontal ultrasonic vibration is developed in this investigation. The comparisons between CSG and RUSM with horizontal ultrasonic vibration are conducted. The kinematic motions of abrasive grains in both processes are discussed and analyzed. Effects of input variables (including tool rotation speed, feedrate, and depth of cut) on output variables (including cutting forces and surface roughness) are also investigated in both CSG and RUSM processes. RUSM with horizontal ultrasonic vibration is proven to be an effective machining method for reducing cutting forces and simultaneously improving machined surface quality.