Powder bed fusion
What is SLM / DMLS and how does it work?
A technology that fully melts metal powder with a high-power laser to produce dense, strong and complex metal parts.
Laser Powder Bed Fusion (Metal LPBF)
In metal LPBF, known as SLM (Selective Laser Melting) and DMLS (Direct Metal Laser Sintering), thin layers of metal powder spread in an inert gas (argon or nitrogen) atmosphere are fully melted by a fiber laser. The result is metal parts with a density close to cast or wrought parts (above 99.5%). Lightweight topology-optimized brackets, mold inserts with internal cooling channels and medical implants are typical applications.
| Typical tolerance | ±0.1 – 0.2 mm |
|---|---|
| Layer thickness | 20 – 60 µm |
| Minimum wall thickness | 0.4 – 1 mm |
| Density | > 99.5% |
| Surface | Ra 6 – 15 µm (as printed); improved by machining and polishing |
| Supports | Required; they also conduct heat to the plate |
Process
SLM / DMLS step by step
- 01
The build chamber is filled with inert gas.
- 02
A blade spreads a 20 – 60 µm layer of metal powder.
- 03
A fiber laser melts the cross-section, welding it to the layer below.
- 04
The process repeats; the part is anchored to the plate with supports.
- 05
Stress-relief heat treatment, wire EDM removal from the plate, support removal and machining follow.
Advantages
- Mechanical properties close to cast/wrought
- Internal channels and lattice structures
- Single-part designs that reduce assembly count
- Hard-to-machine metals such as titanium and nickel alloys
Limitations
- High cost
- Supports and heat treatment are mandatory
- Critical surfaces need machining
Best suited for
- Aerospace brackets
- Medical implants and surgical instruments
- Mold inserts with conformal cooling
- High-temperature parts
Design
SLM / DMLS design guidelines
- Minimum wall thickness0.4 – 1 mm
- Smallest detail0.6 mm
- Minimum hole diameterØ 1.5 mm
- Overhang angle≥ 45° from horizontal; flatter surfaces need support
- Clearance for moving parts0.3 mm
- Text and logosEmbossed ≥ 0.5 mm
Surface and assembly
Post-processing
- Stress relief
- HIP (hot isostatic pressing)
- Wire EDM removal
- CNC finishing
- Bead blasting and polishing
Good to know
Frequently asked questions about SLM / DMLS
What is SLM / DMLS?
In metal LPBF, known as SLM (Selective Laser Melting) and DMLS (Direct Metal Laser Sintering), thin layers of metal powder spread in an inert gas (argon or nitrogen) atmosphere are fully melted by a fiber laser. The result is metal parts with a density close to cast or wrought parts (above 99.5%). Lightweight topology-optimized brackets, mold inserts with internal cooling channels and medical implants are typical applications.
How does SLM / DMLS work?
The build chamber is filled with inert gas. A blade spreads a 20 – 60 µm layer of metal powder. A fiber laser melts the cross-section, welding it to the layer below. The process repeats; the part is anchored to the plate with supports. Stress-relief heat treatment, wire EDM removal from the plate, support removal and machining follow.
What applications is SLM / DMLS suitable for?
SLM / DMLS is especially suitable for aerospace brackets, medical implants and surgical instruments, mold inserts with conformal cooling, high-temperature parts.
How accurate are SLM / DMLS parts?
Typical tolerance is ±0.1 – 0.2 mm. The exact value depends on the machine, material and part geometry.
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