Influence of Fibre Orientation on the Slotting Quality of CFRP Composites Using the Multi-Tooth Mill

Carbon fibre-reinforced plastic (CFRP) composites, prized for their exceptional properties, often encounter surface quality issues during slotting due to their inherent heterogeneity. This paper tackles CFRP slotting challenges by employing multi-tooth mills in experiments with various fibre orientations and tool feed rates. In-plane scratching tests are performed under linearly varying loads; then, slotting experiments are conducted at different parameters. The scratching test results indicate that the fibre orientation and cutting angles have significant influences on forces and fracture process. The slotting experiments demonstrate that cutting forces and surface roughness S of the bottom slotting surface are notably affected by the fibre orientation, with disparities between up-milling and down-milling sides. Reorganising S data by local fibre cutting angle θ highlights consistent S variations between up-milling and down-milling sides for 0° ≤ θ ≤ 90°, with lower S on the up-milling side. However, for 90° < θ ≤ 150°, S variations diverge, with lower S on the down-milling side. Unexpectedly, S on the down-milling side decreases with increasing θ in this range. Additionally, the tool feed rate exerts a more pronounced influence on S on the up-milling side.