Experimental study of machinability of CHSF/PR composites by end milling

Chopped high-silica fiber-reinforced phenolic resin (CHSF/PR) composites are vital in the aerospace field for their exceptional strength-to-weight ratio and near-net-shape manufacturability. Nonetheless, their compression-molded interlocking structures cause complex machining dynamics, creating challenges in surface quality, removal mechanisms, and tool wear. This study investigated the cross-scale effects of fiber distribution using orthogonal experiments and multi-scale characterization. Experimental results showed CHSF/PR composites have significantly higher cutting forces than unidirectional composites, demonstrating enhanced machining resistance. Force fluctuations (20% amplitude) stemmed from competitive shear fracture and fiber buckling. Surface roughness increased by 110% and 53% with cutting width and depth, respectively, attributed to pit-delamination hybrid damage triggered by abrupt changes in fiber orientation. Tool wear demonstrated a critical distance threshold; post-coating-delamination wear rates surged due to abrasive particle embedding and interfacial thermal stress concentration. This study establishes a theoretical framework for optimizing CHSF/PR composites machining, providing critical technical foundations for precision aerospace components.