Additive and Subtractive Hybrid Manufacturing Strategy Integrating a NURBS-Based workflow for Precision Components

Fused Deposition Modeling (FDM) is among the most widely used Additive Manufacturing (AM) technologies, valued for its capacity to produce complex thermoplastic parts at relatively low cost. Although initially limited to prototyping due to the poor mechanical performance of unreinforced polymers, recent advances in high-performance materials, particularly carbon fibre-reinforced Polyetherketoneketone (PEKK), have significantly broadened its industrial applications. These composite thermoplastics offer enhanced mechanical, thermal, and chemical properties, enabling the production of functional load-bearing components. Moreover, improvements in printer resolution and process control have increased the geometric accuracy and repeatability of FDM outputs.Nonetheless, meeting the stringent precision requirements of certain applications remains a challenge. Additive and Subtractive Hybrid Manufacturing (ASHM) has emerged as a promising solution by combining 3D printing with subtractive post-processing to enhance geometric accuracy and surface finish, albeit at a higher cost. Furthermore, the limitations of traditional AM workflows based on STL polygonal representations that inherently reduce geometric fidelity can be overcome by adopting a NURBS-based approach, which enhances direct and more accurate G-code generation.This study assessed the combined use of ASHM and a NURBS-based workflow to manufacture cylindrical components with enhanced precision. Three methodologies were compared: conventional STL-based AM, precise AM using NURBS trajectories, and hybrid manufacturing integrating post-process milling. Experimental results revealed substantial improvements in geometric quality. NURBS-based AM achieved up to 49% and 43% enhancement in roundness and cylindricity, respectively, over traditional STL-based printing. The incorporation of ASHM further improved these metrics, reaching up to 73% and 78% geometric accuracy. These findings underline the effectiveness of combining advanced modelling and hybrid manufacturing for producing high-precision parts in cost-sensitive contexts.