SLM — Selective Laser Melting
A 200–400 W laser fully melts metal powder in an inert atmosphere — producing full-density end-use metal parts in steel, aluminium, and titanium.
SLM
Selective Laser Melting
From metal powder to fully-dense end-use parts
- Metal powder spread across build plate inside an argon-filled chamber.
- 200–400 W Yb-fibre laser fully melts powder into a dense weld pool.
- Weld pool fuses to layer below — full density (95–99.9%) achieved.
- Build plate drops, fresh powder spreads — process repeats.
- Post-print: stress relief → wire-EDM cut → support removal → heat treatment → bead-blast → post-machining.
What SLM is great at — and where it falls short
- Full-density metal parts (95–99.9%)
- Mechanical properties match wrought / cast equivalents
- Complex internal geometry (cooling channels, lattices)
- Wide alloy range (Al, SS, Ti, tool steel)
- No tooling cost for low-volume metal parts
- 30–60% weight savings via topology optimisation
- Highest cost of all 3D printing processes
- Rough as-printed surface (Ra ~8 µm) needs finishing
- Critical tolerances require post-machining
- Build envelope limited to 250×250×325 mm
- Longest lead time (5–10 days, 8–13 with HIP)
- Metal supports require grinding/machining to remove
When to choose SLM
- The part genuinely needs to be metal (load, heat, conductivity).
- Complex geometry that can't be CNC-machined.
- Low-volume metal production runs or weight-optimised structural parts.
SLM alloys we stock
Aluminium AlSi10Mg
The most popular aluminium alloy for metal 3D printing. Silicon content improves melt flow and print consistency, while the resulting alloy delivers strong, lightweight parts with good thermal conductivity. Ideal for weight-sensitive applications in aerospace, automotive, and robotics where metal is required but mass must be minimised.
Stainless Steel SS316L
A low-carbon austenitic stainless steel and one of the most widely used materials in metal 3D printing. Excellent corrosion resistance — including marine, chemical, and food-contact environments — combined with high toughness and good mechanical strength. The molybdenum content makes it more corrosion-resistant than standard 304 stainless steel.
Mould Steel MS1 (1.2709)
A maraging steel designed for the most demanding tooling and industrial applications. Delivers exceptional hardness, thermal fatigue resistance, and dimensional stability — making it the material of choice for injection mould cavities, conformal cooling inserts, and high-wear industrial tooling. Requires heat treatment post-print to reach full hardness.
Titanium Ti6Al4V
The world's most widely used titanium alloy, accounting for over 50% of global titanium usage. Combines an exceptional strength-to-weight ratio with outstanding corrosion resistance and full biocompatibility — harder than aluminium, lighter than steel, and more corrosion-resistant than stainless steel. The benchmark material for aerospace structures, medical implants, and high-performance motorsport components.
The numbers that matter
What tolerance means in practice: ±0.2 mm as-printed means a 10 mm hole prints between 9.8 mm and 10.2 mm — fine for non-critical features. For bearing seats, threads, sealing faces, we leave 0.3–0.5 mm machining stock and CNC-finish to ±0.025 mm. Always budget for post-machining at the design stage.
Design rules that save dollars
Machining Stock
Leave 0.3–0.5 mm machining stock on critical faces.
Why: as-printed ±0.2 mm isn't tight enough for precision-fit features.
Internal Channel Sizing
Internal channels min 0.5 mm diameter for powder removal.
Why: trapped metal powder is dangerous and adds weight unpredictably.
Support Access
Design support structures to be physically reachable for removal.
Why: metal supports must be ground or machined off — unreachable supports = scrap.
Topology Optimisation
Use topology optimisation or generative design to reduce mass and cost.
Why: SLM is priced by volume of metal — less mass means lower cost.
Threaded Holes
Always post-machine threads for tight or critical applications.
Why: as-printed threads are loose and inconsistent — fine for clearance, not for precision fits.
Lattice Strut Sizing
Lattice minimum strut diameter 0.4 mm.
Why: laser spot size and weld-pool dynamics limit how thin a strut can melt cleanly.
How SLM stacks up
| Property | FDM | SLA | SLS | MJF | SLM |
|---|---|---|---|---|---|
| Cost | $ | $$ | $$$ | $$$ | $$$$$ |
| Surface Finish | Visible layers | Near-smooth | Slightly grainy | Slightly grainy | Rough as-printed |
| Detail | Moderate | Excellent | High | High | High |
| Tolerance | ±0.5 mm | ±0.15 mm | ±0.3 mm | ±0.2 mm | ±0.2 / ±0.025 mm* |
| Strength | Anisotropic | Near-isotropic | ~85% iso | ~95% iso | Near-isotropic |
| Speed | Fast | Medium | Medium | Fast | Slow |
| Material Range | Wide | Resins | PA12 | PA12, TPU | Al, SS, Ti, tool steel |
| Support-free | No | No | Yes | Yes | No |
| Best for | Prototypes | Visual & detail | Complex geometry | Production batches | Metal end-use |
Key Applications
Aerospace Brackets
Weight-optimised structural components.
Topology optimisation cuts 30–60% mass at no strength loss.
Medical Implants
Patient-specific bone replacements, surgical guides.
Ti6Al4V is biocompatible; HIP gives fatigue-critical density.
Motorsport Components
Brake calipers, manifolds, suspension nodes.
Custom alloys + lattices unlock performance.
Tooling Inserts
Injection-mould inserts with conformal cooling channels.
Internal channels follow part shape — impossible by drilling.
Marine & Chemical Fittings
Valves, manifolds, sea-water-rated parts.
316L stainless resists corrosion and high temperature.
Legacy Replacement Parts
One-off replacements for out-of-production equipment.
No tooling cost; you ship metal in a week.
SLM, answered
SLM enables internal geometry, lattices, and topology-optimised shapes that are impossible to machine. CNC is faster and lower cost for simple shapes. For complex metal parts where geometry matters, SLM wins; for solid blocky parts, CNC wins.
Most do, for critical features — bearing seats, threads, sealing faces, mounting holes. Budget for post-machining at the design stage and leave 0.3–0.5 mm of machining stock on those features.
Hot Isostatic Pressing closes internal micro-pores for fatigue-critical applications like aerospace structural parts or medical implants. It adds about 3 days but is essential for any part subject to repeated cyclic loading.
Printed threads are possible but loose. For tight thread fits — sealing, torque-critical, repeated assembly — always print a pilot hole and tap or thread-machine post-print.
Full-density SLM (99%+) reaches strength similar to or slightly higher than cast equivalents. Heat treatment brings it close to wrought (rolled / forged) properties. With HIP, fatigue performance also matches wrought.
AlSi10Mg (aluminium), Stainless 316L, Titanium Ti6Al4V, and Mould Steel MS1 (1.2709) as standard. Inconel 718, copper alloys (CuCrZr), and maraging steel are available on request with lead-time impact.