Alternative lubrication-cooling approaches for broaching medium-carbon steel: Machining performance and life cycle analysis

• This paper conducts a comprehensive evaluation of the performance and sustainability of broaching with different lubrication strategies. • Broaching tools manufacturing and reconditioning significantly influence energy consumption and environmental impact. • TiAlN-coated broaching tools achieve superior dry cutting performance in F-114 steel with minimal environmental footprint. • Optimized cutting speed and tool reconditioning maximize tool life and drastically reduce environmental impact. This study evaluates the machining performance and environmental impact of the broaching process under different cutting and lubrication/cooling conditions, including conventional, cryogenic, and dry strategies. A life cycle assessment ( LCA ) was conducted using SimaPro 9.5.0.2 applying ReCiPe 2016, IPCC 2021 GWP100 , and Cumulative Energy Demand ( CED ) V1.11 methods. The IPCC method assessed global warming potential ( GWP ) from greenhouse gas emissions, while CED method quantified total energy consumption throughout the process. Experimental tests involved generating 90 slots in a 500 mm diameter AISI 1045 steel disc using an HSS-MT (ISO K20-K40) broaching tool on a vertical broaching machine. Results showed that dry broaching with a TiAlN-coated tool was the most effective strategy, achieving three times the efficiency of conventional broaching with an uncoated tool and ten times the efficiency of cryogenic broaching for a flank wear of <0.10 mm. In addition, cryogenic broaching exhibited comparable performance to conventional high-speed broaching (40 m/min), indicating that cryogenic cooling does not present significant advantages under these conditions. Energy analysis revealed that lubrication/cooling systems were the dominant contributors to total energy use. Cryogenic machining reduced energy consumption by 40 % compared to conventional high-speed broaching and by 88 % compared to conventional low-speed broaching, mainly due to longer lubricant pump use. Tool reconditioning by regrinding further minimized environmental impact, reducing global warming ( GWTT ) by 81 % and fossil resource scarcity ( FRC ) by 66 %. These findings highlight the importance of advanced coatings and tool reuse in optimizing machining efficiency and sustainability, providing a framework for more energy-efficient and environmentally friendly broaching processes. This work provides practical guidance for implementing more energy-efficient and environmentally responsible broaching operations.