Laser Powder Bed Fusion (DMLS/SLM)

Laser Powder Bed Fusion builds dense metal parts from powder with a laser, enabling complex internal geometry, fine features, and near-wrought mechanical properties.

Overview

Laser Powder Bed Fusion (DMLS/SLM) is a metal 3D printing process that uses a laser to selectively melt thin layers of metal powder, creating fully dense parts directly from CAD. It excels at complex, compact geometries: internal channels, lattice structures, conformal cooling, and topology-optimized forms that are difficult or impossible to machine or cast.

Use it for low to medium production volumes where geometry drives performance—lightweight structures, thermal management, and consolidated assemblies. Expect good mechanical properties comparable to wrought material after proper heat treatment, but with higher part cost than conventional machining for simple shapes. Tradeoffs include limited build envelope, the need for support structures and their removal, relatively rough as-printed surfaces, and potential distortion if you ignore orientation and residual stresses. Critical interfaces usually require post-machining for tight tolerances and good surface finish.

Common Materials

  • AlSi10Mg
  • Stainless Steel 316L
  • 17-4 PH Stainless Steel
  • Inconel 718
  • Ti-6Al-4V

Tolerances

±0.003" to ±0.005" on features <4"; up to ±0.010" on larger dimensions before post-machining

Applications

  • Conformal cooling inserts for injection molds
  • Lightweight aerospace brackets and mounts
  • Heat exchangers and lattice-filled thermal structures
  • Complex fluid manifolds with internal passages
  • Patient-specific orthopedic implants
  • Topology-optimized structural nodes and joints

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

Choose Laser Powder Bed Fusion when part performance depends on complex geometry, internal channels, or weight reduction rather than minimizing per-part cost. It fits low to medium volumes, functional prototypes, and production parts requiring good mechanical properties in small to medium sizes. It’s ideal when you can consolidate multiple components into one printed assembly and accept post-machining on critical surfaces.

vs Electron Beam Melting (EBM)

Choose Laser Powder Bed Fusion over EBM when you need finer feature resolution, thinner walls, and better surface finish on small to medium parts. It is better suited for intricate channels, sharp details, and applications where tighter dimensional control and smoother surfaces reduce downstream machining.

vs Binder Jetting (Metal)

Choose Laser Powder Bed Fusion when you need fully dense, high-strength parts directly from the printer without relying heavily on sintering and infiltration. It is preferable for pressure-containing components, fatigue-critical parts, and geometries that cannot tolerate shrinkage variation from debinding and sintering.

vs Direct Energy Deposition (DED)

Choose Laser Powder Bed Fusion when you need finer resolution, thinner walls, and more intricate internal structures than DED can provide. It is the better fit for small, detailed parts rather than large repairs, cladding, or coarse near-net builds that will see heavy subsequent machining.

vs CNC machining

Choose Laser Powder Bed Fusion over CNC machining when tool access, internal channels, or severe undercuts make machining impractical or extremely costly. It is advantageous when you can reduce part count by consolidating assemblies into a single complex printed part and then finish only the critical interfaces by machining.

Design Considerations

  • Target self-supporting geometries where possible; keep overhangs above 45° or add sacrificial features that are easy to remove
  • Maintain minimum wall thicknesses and strut diameters per material (often ≥0.020–0.040") to avoid distortion or incomplete fusion
  • Provide clear powder escape paths for internal cavities with access holes sized and located for easy powder removal
  • Orient parts to minimize support volume on critical surfaces and to align major load paths with favorable build directions
  • Reserve machining stock on critical interfaces and holes; specify which surfaces will be post-machined and required final tolerances
  • Limit part size to the available build envelope and consider splitting very large parts into joints that can be printed and then joined mechanically or welded