Fused granular modeling (FGM) is an emerging additive manufacturing technique offering cost-effective, pellet-based fabrication with high material flexibility and throughput. However, the influence of key process parameters in FGM remains insufficiently understood. This study aims to investigate the effect of print speed on the mechanical performance of polylactic acid components produced using a commercial pellet-based system (Tumaker NX Modular), with emphasis on identifying strength–ductility trade-offs.
Five print speeds ranging from 2,400 to 7,200 mm/min were examined while keeping all other processing parameters constant. ASTM D638 Type I tensile specimens were tested under uniaxial loading, from which eight mechanical response parameters were extracted. Dimensional accuracy measurements and optical microscopy were also performed to assess geometric consistency, interlayer bonding and void formation.
Increasing print speed resulted in reduced yield strength, fracture strength and stiffness, while ductility and toughness increased, revealing a clear trade-off between mechanical performance and production efficiency. Ultimate tensile strength showed minimal sensitivity to print speed, whereas yield stress and resilience exhibited non-monotonic trends, indicating limited controllability through speed alone. Microstructural and dimensional analyses confirmed increased void content and reduced interlayer fusion at higher print speeds.
This study provides a focused evaluation of print speed as a critical parameter in pellet-based FGM using a commercial system. By directly linking print speed to mechanical response, dimensional accuracy and microstructural quality, the work offers practical guidance for selecting processing conditions that balance efficiency with mechanical performance.
