Laser Powder Bed Fusion (DMLS/SLM)

Laser powder bed fusion (DMLS/SLM) builds fully dense metal parts layer-by-layer from powder, enabling complex internal features with support removal and post-machining.

Overview

Laser Powder Bed Fusion (LPBF), often called DMLS or SLM, fuses thin layers of metal powder with a laser to form near-net-shape parts. It excels at complex geometry: internal channels, lattices, weight-optimized structures, and part consolidation that can’t be machined or cast economically.

Choose LPBF for low-to-medium volumes where performance drives the design—high-value parts, rapid iteration, or geometries that eliminate assemblies. Expect post-processing: stress relief, support removal, surface finishing, and usually machining of datum features, threads, sealing surfaces, and tight bores.

Tradeoffs are cost per part, build size limits, and surface roughness. Downfacing surfaces and internal passages need careful design for support, powder removal, and distortion control. Lead time and quality depend heavily on orientation, support strategy, and process controls (powder handling, parameter sets, and inspection).

Common Materials

  • Ti-6Al-4V
  • 316L stainless steel
  • 17-4 PH stainless steel
  • AlSi10Mg
  • Inconel 718
  • CoCrMo

Tolerances

±0.005" (±0.13 mm) typical; ±0.002" (±0.05 mm) achievable on critical features with finish machining

Applications

  • Topology-optimized aerospace brackets
  • Conformal-cooled injection mold inserts
  • Patient-specific orthopedic implants
  • Rocket engine injectors and manifolds
  • Heat exchangers with internal microchannels
  • High-performance lattice structures and energy absorbers

When to Choose Laser Powder Bed Fusion (DMLS/SLM)

LPBF fits parts where geometry is the differentiator: internal channels, lattices, organic shapes, and assembly consolidation. It makes the most sense for prototypes through tens-to-hundreds of pieces where material performance matters and tooling cost is hard to justify. Plan for secondary operations to hit sealing surfaces, bearing fits, and cosmetic requirements.

vs Electron Beam Melting (EBM)

Choose LPBF when you need finer feature resolution, better surface detail, and thinner walls than typical EBM capability. LPBF is also a better fit when you want a broader material menu and tighter control of small internal passages, with the tradeoff of potentially higher residual stress and more support strategy work.

vs Binder Jetting (Metal)

Choose LPBF when you need higher as-built density, strength, and pressure-tightness without relying on sintering shrinkage models. LPBF is the safer choice for thin walls, intricate internal features, and critical mechanical properties, accepting higher per-part cost and slower build rates.

vs Direct Energy Deposition (DED)

Choose LPBF for small-to-medium parts needing fine details, thin walls, and complex internal geometry. LPBF generally delivers better dimensional consistency and surface finish than DED; DED is stronger when you need large envelopes, repairs, or adding features onto existing parts.

vs CNC machining

Choose LPBF when the part has trapped/internal features, lattice structures, or multi-axis undercuts that make machining impractical or require many assemblies. LPBF also enables part consolidation to remove fasteners and brazed joints, then machining can finish datums and precision fits.

Design Considerations

  • Provide powder escape paths for all internal cavities (add cleanout holes and avoid blind, trapped volumes).
  • Avoid long, thin overhangs; design self-supporting angles and minimize downfacing surfaces to reduce supports and improve finish.
  • Add machining allowance on critical interfaces (datums, bores, threads, sealing surfaces) and call out which features will be post-machined.
  • Use uniform wall thickness where possible and avoid abrupt section changes to reduce distortion and recoater-interaction risk.
  • Orient critical surfaces away from support contact and specify acceptable surface roughness separately for as-built vs machined areas.
  • Define inspection strategy early (CT, CMM, coupon testing) and include material/heat treatment requirements on the print drawing.