Directional Deviations of PA11-FR Fabricated by PBF-LB/P Process under Constant Energy Density

Abstract

Geometric complexity and process conditions strongly influence dimensional accuracy in laser-based powder bed fusion of polymers (PBF-LB/P). In this study, the dimensional behavior of flame-retardant polyamide 11 (PA11-FR) fabricated by PBF-LB/P under constant energy-density conditions was systematically investigated. Standardized test artifacts, including linear features, resolution pins, holes, slots, ribs, and Z-axis structures, were manufactured and distributed across the build platform to evaluate geometric, directional, and spatial effects on dimensional deviation. Statistical analysis revealed that geometric feature size is the dominant factor affecting dimensional error (F = 69.38, p < 0.001), exhibiting the largest partial contribution to dimensional variation (74.5%). In contrast, the build platform location showed no statistically significant influence. Directional analysis indicated a significant effect of build orientation (F = 5.28, p = 0.006), with the largest deviations observed along the build direction. Regression analysis further confirmed a statistically significant relationship between nominal feature size and absolute dimensional error (p < 0.001), described by the model: Absolute Error (%) = 1.927 − 0.02574 × Nominal Feature Size. The results demonstrate that dimensional deviations increase substantially for small-scale geometries (<10 mm), while features larger than approximately 20 mm exhibit stable dimensional behavior. These findings highlight the geometry-dependent dimensional accuracy of PA11-FR in the polymer PBF-LB/P and provide practical guidelines for designing dimensionally reliable additively manufactured polymer components.