Investigations on tool clogging and surface integrity in ultrasonic vibration-assisted slot grinding of unidirectional CFRP

Carbon fibre-reinforced plastic (CFRP) composites have been widely used in the field of aerospace and transportation because of their excellent mechanical properties. However, excessive tool clogging commonly occurs because of low chip storage space, thereby leading to workpiece failure. The slot grinding experiments with and without ultrasonic vibration were performed by using abrasive tools with defined grain pattern to improve tool life. The mathematical model of the fibre cutting angle in ultrasonic vibration-assisted slot grinding (USG) was established. The influences of ultrasonic vibration on the grinding force, tool clogging and surface integrity of unidirectional CFPR were discussed quantitatively. Results show that the USG featured lower grinding force, shorter fibre chip and better surface integrity than the conventional slot grinding (CSG). In addition, the lowest and highest reduction rates of grinding forces are obtained by using the fibre orientation of 90 degrees and 135 degrees, respectively. The maximum fibre chip lengths produced in USG are approximately 78% and 66% lower than those in CSG with fibre orientations of 0 degrees and 90 degrees, respectively. Several adhesive chips are observed on the USG tool surface. The chip storage spaces in CSG are filled with adhesive chips. The USG has a positive influence on surface roughness and damage because of the changes in fibre cutting angle. Compared with CSG, the USG produces similar fibre fracture patterns, except at the fibre orientation of 0 degrees. Furthermore, the surface defects in USG are lower than those in CSG.