Toward a hybrid material extrusion technique: exploring the benefits of integrating fused deposition modeling and material injection

Fused Deposition Modeling (FDM), an established additive manufacturing (AM) method, is efficient in producing intricate and customized parts; however, it suffers from inferior mechanical properties due to weak interlayer bonding. This has led to growing interest in hybrid AM techniques that combine FDM with secondary processes, such as subtractive, surface treatment, and thermal, to enhance properties and manufacturing efficiency beyond what is achievable through individual methods. To address the limitations of these existing methods, this paper establishes a foundational framework for integrating material injection (MI) with FDM for the development and implementation of a novel hybrid FDM–MI manufacturing approach. The experimental campaign for the integrated FDM–MI method was accomplished by incorporating MI as a post-process to the FDM method and examining the effect of coupling these two methods. The results of this integrated FDM–MI method showed maximum improvements of 25% and 35.6% in the impact and tensile strength, respectively, compared to the traditional FDM method. These findings were corroborated through morphological analysis of fracture surfaces via field emission scanning electron microscopy observations (FE-SEM) and stereomicroscopy, and further supported by thermal characterization using differential scanning calorimetry (DSC) and in-situ temperature profiling. This study provides insight into the mechanisms influencing process integration and offers a comprehensive assessment of the proposed integrated FDM–MI manufacturing technique.