From CAD to CNC A toolpath driven framework for hybrid additi 2026 Next Mat

Hybrid additive – subtractive manufacturing (HASM) has emerged as a powerful paradigm for overcoming the intrinsic limitations of standalone additive manufacturing (AM) and subtractive manufacturing (SM) by combining geometric design freedom with the dimensional accuracy and surface quality achievable through CNC machining. Despite significant progress in metal-based hybrid systems, polymer-based HASM remains comparatively underexplored, despite growing industrial demand for high-precision, high-performance polymer components. This review presents a critical and structured analysis of polymer-based HASM from a toolpath-driven and digitally integrated perspective. A systematic literature methodology was employed, screening approximately 210 publications and selecting 114 peer-reviewed studies across seven thematic categories. Particular attention is given to the machinability and surface integrity of engineering polymers including PLA, ABS, PETG, PC, PA, PEEK, photopolymers, and fiber-reinforced composites, along with hybrid toolpath planning, machining allowance management, and CAD – CAM – CNC interoperability. Emerging technologies — artificial intelligence, digital twins, sensor-based monitoring, and adaptive process control — are critically examined as key enablers of next-generation hybrid systems. Based on identified research gaps, a toolpath-driven closed-loop integration framework is proposed, unifying design, additive deposition, subtractive finishing, and real-time feedback within a single cyber-physical manufacturing environment. The findings establish that seamless AM – SM toolpath integration, intelligent process optimization, and standardized quality assessment are the critical enablers for advancing polymer HASM toward industrially scalable, data-driven, and sustainable smart manufacturing.