Drilling Temperature and Cutting Force Analysis in Additive-Modified CFRP Composites

Carbon fiber-reinforced polymer (CFRP) composites are difficult to machine due to their heterogeneous structure, leading to high force and temperatures during drilling. This study investigates the synergistic effects of graphene and wax additives on cutting forces and temperature in CFRP drilling. A full factorial design was employed with cutting speed (50–250 m/min), feed rate (0.005–0.11 mm/rev) and material composition (nine combinations of 0–2 wt% graphene and 0–2 wt% wax), resulting in 675 tests. Feed rate emerged as the dominant factor controlling cutting force, while temperature was governed by complex interactions. The addition of 1% wax reduced force by 33% and temperature by 22%, whereas 2% graphene alone reduced force by 35% and temperature by 18%. However, combining 2% graphene with wax increased force by 14–16% compared to graphene alone, indicating a transition from lubrication to reinforcement dominance (Wax:Graphene interaction: F = 103.29). No corresponding temperature increase was observed, revealing a decoupling of mechanical and thermal responses (r = 0.01). Material modification improves CFRP machinability, but optimal formulations must balance competing mechanisms. The highest stability was achieved with 1% wax/0.25% graphene for cutting force (±4.04 N) and 2% wax/0.25% graphene for temperature (±1.48 °C).