Introducing EM shielding capability in laser sintered polyamide parts by in-situ deposition of stainless steel fibers

Electromagnetic (EM) shielding is critical for reliable electronic systems and mitigating electromagnetic pollution. Additive manufacturing (AM), particularly Polymer Laser Powder Bed Fusion (PBF-LB/P), can offer design flexibility for EM shielding components. However, PBF-LB/P shielding materials remain limited, with existing approaches primarily relying on nanoparticles or short fibers due to feedstock flowability and powder-spreading constraints. This study introduces a PBF-LB/P approach integrating in-situ deposition of long discontinuous stainless steel fibers (SSF) with a length of 2 mm into a polyamide 12 (PA12) matrix. Composites with SSF contents of 0.7, 1.4, and 2.2 wt% were fabricated using an in-situ fiber deposition system and the fiber orientation, connectivity, EM shielding effectiveness (SE), and mechanical properties were characterized. EM shielding tests in the 8.2-12.4 GHz range demonstrated a systematic SE improvement from < 1 dB for pure PA12 to 6 dB, 9 dB, and 15 dB for 1.5 mm thick samples containing 0.7, 1.4, and 2.2 wt% SSF, respectively. The increase in shielding effectiveness was accompanied by an increase in in-plane fiber connectivity, derived with X-ray Computed Tomography. Mechanical testing indicated minimal impact on tensile strength but reduced ductility at higher fiber contents. This work establishes in-situ fiber deposition during PBF-LB/P as a promising route for lightweight 3D-printed EM shielding components.