Machinability of Basalt/PBS sustainable composites: a comprehensive experimental analysis

Basalt fiber reinforced polybutylene succinate (BFPBS) composite offer competitive solutions for medium load applications but face significant drilling challenges. Present study seeks to perform an exhaustive machinability analysis and optimize pivotal drilling variables, to mitigate delamination and enhance machining efficacy in BFPBS laminates. Experimental exploration involved three distinct drill geometries: an 8 mm twist drill and two modified step drills, facilitating scrutiny of pilot diameter's impact on drilling behavior. Mapping force signals, morphological analysis, chip formation investigation, and specific cutting energy calculation were conducted to deepen comprehension of BFPBS machinability. Modified step drill showed superior performance with lower thrust force and torque. Feed rate primarily affected thrust force, whereas tool geometry notably influenced exit delamination. Multiple linear regression models enabled Genetic Algorithm optimization, revealing Pareto optimal sets balancing thrust, torque, and delamination. Step drills show potential for reduced energy use and improved efficiency in BFPBS composite machining, benefiting various industries.