Machinability analysis of UD-GFRP composites in edge trimming with diamond-coated burr tools at various fiber orientations

Machining operations that are usually required during the manufacturing process of fiber-reinforced polymers (FRPs) are likely to generate numerous specific defects on the machined parts. Cutting tools with specific geometries, such as burr tools with many pyramidal teeth, help to reduce this type of defect. Previous studies in milling with this kind of tool focused mainly on multidirectional (MD) FRP composites. However, it is well known that fiber orientation is a critical parameter in FRP machining. Accordingly, this paper presents a machinability analysis of unidirectional (UD) FRP composites in edge trimming at various fiber orientations, for the specific case of burr tools. Edge trimming experiments are conducted using glass fiber reinforced polymer (GFRP) composites and diamond-coated burr tools. For each machining test, cutting forces, machined surface temperature and surface quality are quantified, as well as defects on external plies, which are characterized with a device specifically developed for this purpose. The results demonstrate that all the parameters are affected greatly by fiber orientation. The maximum temperature rise and the resultant force generally move in the same direction. The surface irregularities, and the maximum rise in temperature, move globally in opposite directions. Uncut fibers on the lower face of the workpiece are related to axial forces and may be facilitated by high temperatures. Moreover, the effect of fiber orientation on cutting forces in the workpiece plane, machined surface temperature and surface quality is analogous to previous literature on orthogonal cutting. • Surface quality is analyzed at fiber scale and macro-scale with areal parameters. • Uncut fibers are quantified with a dedicated device and specific image processing. • Resultant force, temperature rise and surface quality move in the same direction. • Uncut fibers are related to axial forces and perhaps favored by high temperature. • The effect of instantaneous fiber orientation is similar to orthogonal cutting.