Impact of fiber orientation on cutting forces and surface quality in flax/epoxy composite machining

Flax/epoxy composites are recognized as an eco-friendly alternative to synthetic fibers in engineering. Understanding how fiber orientation affects cutting forces and surface characteristics is essential for machining these materials. This study investigates the relationship between fiber orientation and cutting forces (feed, normal, passive) as well as surface roughness in flax/epoxy composites. Results show that fiber orientation significantly impacts cutting forces. Cutting parallel to fibers (0 degrees and 90 degrees orientations) generally requires less force, with 0 degrees needing higher normal force. At 0 degrees orientation, feed force is 46.47 N, normal force is 58.86 N, and passive force is 54.44 N. At 90 degrees orientation, feed force is 56.66 N, normal force is 44.68 N, and passive force is 50.95 N. Oblique orientations (45 degrees and -45 degrees) require higher forces, especially 45 degrees, with the highest normal force of 77.95 N. Surface roughness analysis shows 90 degrees orientation results in the lowest average roughness (Ra) of 10.97 mu m but the highest surface roughness (Sa) of 34.25 mu m. Conversely, 45 degrees orientation has the highest Ra of 14.2 mu m but lower Sa of 22.6 mu m. Ra and Sa values for 0 degrees orientation are 13.72 mu m and 24.6 mu m, and for -45 degrees orientation, they are 12.3 mu m and 21.8 mu m. Correlation analysis reveals significant relationships between cutting parameters and surface quality, with higher feed rates correlating with smoother surfaces (lower Sa and Ra values). Fiber orientation also significantly influences fluffing defects, with 0 degrees orientation minimizing these defects, while 45 degrees and -45 degrees orientations result in varied patterns.