Sustainable optimization of drilling performance in Al6061–B4C composites: process–property interactions for lightweight engineering applications

The demand for sustainable lightweight materials in automotive and aerospace sectors necessitates the development of metal matrix composites with optimized machinability and performance. In this study, Al6061–B4C composites containing 3, 6, and 9 wt% reinforcement were fabricated using stir casting and systematically evaluated for mechanical behavior and drilling performance. Contrary to conventional expectations, the incorporation of B4C resulted in a reduction in hardness, attributed to casting-induced porosity and particle agglomeration, highlighting critical processing–property limitations in composite fabrication. Drilling experiments were designed using a Taguchi L9 orthogonal array to investigate the influence of feed rate, spindle speed, and drill diameter on surface roughness. Statistical analysis revealed that feed rate is the dominant parameter governing surface quality across all compositions, contributing up to 52% of variation, while drill diameter becomes increasingly significant at higher reinforcement levels due to enhanced abrasive interactions. The 3 wt% B4C composite exhibited superior machinability under optimized conditions (1160 rpm spindle speed, 0.575 mm/rev feed rate, 6 mm drill diameter), achieving improved surface integrity with reduced tool–workpiece interaction effects. The study establishes critical process–property–machinability relationships and demonstrates that optimal reinforcement content must balance mechanical enhancement and manufacturability. These findings provide actionable insights for sustainable manufacturing of lightweight components, contributing to resource-efficient production strategies in advanced engineering applications.