Process selection
SLS 3D Printing vs MJF 3D Printing
SLS sinters nylon powder with a CO2 laser tracing each cross section. MJF jets fusing agent across the powder bed and fuses whole layers with an infrared lamp pass. The core trade: SLS offers a wider material catalog and finer laser control; MJF offers faster builds, lower powder refresh cost, and denser parts.
| SLS 3D Printing | MJF 3D Printing | |
|---|---|---|
| Layer height | 0.10 to 0.12 mm | 0.08 mm standard |
| Dimensional tolerance | ±0.25 mm or ±0.3% | ±0.2 mm or ±0.3% |
| Machine cost | $30k benchtop, $250k to $500k industrial | $300k to $500k with processing station |
| Full-bed build time | 20 to 30 hr plus 10 to 12 hr cool-down in machine | 10 to 16 hr, fast-cool station frees printer |
| Powder refresh rate | 30 to 50% virgin PA12 | 20% virgin PA12 |
| Materials | PA12, PA11, TPU, glass and CF filled, PEKK on some machines | PA12, PA11, TPU, PA12 GB; shorter list |
| Part appearance | White to light gray, dyeable | Uniform gray to black only |
Choose SLS 3D Printing when
- Material breadth: PA11, filled grades, or high-temp polymers
- White or color-dyed parts where MJF gray is a problem
- Lower entry cost via benchtop SLS around $30,000
Choose MJF 3D Printing when
- Production runs where 2x faster bed cycles cut unit cost
- Slightly denser, more isotropic PA12 with better Z strength
- Lower powder cost per part from the 20% refresh rate
The verdict
For PA12 production parts at quantities above a few hundred, MJF usually quotes 15 to 30% cheaper and turns builds faster. Pick SLS when the material list matters, when parts must be white or dyed a specific color, or when a $30,000 benchtop machine fits an in-house strategy.
Cost comparison
Both are service bureau processes for most shops: benchtop SLS starts near $30,000, but industrial SLS and MJF cells run $250,000 to $500,000 with powder handling. A palm-size PA12 part quotes at $8 to $30 either way at low volume. MJF's roughly 2x faster bed cycles and 20% powder refresh (versus 30 to 50% for SLS PA12) cut unit cost 15 to 30% at high nesting density, so the crossover to MJF typically lands past a few hundred parts per order.
Common questions
Is there a real strength difference between SLS and MJF PA12?
Both print PA12 at roughly 48 MPa tensile. MJF parts run slightly denser and more isotropic, with Z-direction elongation typically better than SLS. For most brackets, housings, and ducts the difference is inside normal lot variation; geometry and nesting orientation matter more.
Why do MJF quotes drop faster with quantity?
MJF fuses a full layer per lamp pass, so bed time barely changes as you pack more parts in, and the 20% powder refresh rate versus 30 to 50% for SLS cuts material overhead. Dense nesting spreads a fixed build cost across more parts.