MJF — HP Multi Jet Fusion
MJF 3D printing for consistent nylon batches from 10 to 10,000 parts
HP Multi Jet Fusion fuses full layers of PA12 powder in one IR pass. Faster than SLS, tighter Z-axis strength, and dark-grey parts that look production-grade out of the machine.
Batch-consistent tolerance
- 1Upload STEP / STL and batch quantity
- 2DFAM check — walls, holes, orientation
- 3Full-bed MJF print + IR fusion
- 4Bead blast, optional dye, dimensional QC, shipped
Quick answer
MJF (HP Multi Jet Fusion) is a powder-bed process that fuses full layers of PA12 with a fusing agent and IR lamps, instead of a point-by-point laser. Choose MJF for high-throughput production runs (100–10,000+ parts) in PA12, PA12 GB or TPU when you want consistent mechanical properties and a fine dark-grey finish. Tolerance ±0.3%, min wall 0.5 mm, build volume 380 × 284 × 380 mm.
Applications
What MJF is good for
MJF earns its place when you need to print many nylon parts, consistently, without the extra dye step.
- End-use production runs from 100 to 10,000 parts in PA12
- Consumer product enclosures and covers (dark grey or dyed black)
- Automotive interior brackets, clips and fasteners
- Medical device housings requiring biocompatible PA12 grades
- Robotics grippers, end-effectors and adapter plates
- Ductwork and manifolds with complex internal geometry
- Ergonomic hand tools and jigs (matte, uniform surface)
- Serial spare parts for machinery and equipment
- Wearables and orthotics in TPU for flexible components
Process
How MJF works
Four stages, engineered for throughput.
Preparation and nesting
Parts are oriented (Z-axis usually along the longest dimension for surface consistency) and nested to fill the build tightly.
Fusing and detailing agents
The inkjet head deposits a carbon-based fusing agent where the part forms and a detailing agent at the edges to keep features crisp.
IR lamp fusion
Two IR lamps sweep the bed. Treated powder melts and fuses in a single pass per layer. Layer height 80 µm.
Cool-down, blast and QC
Slow cool-down, depowdering, bead blast, optional dye or vapor smooth. Sample dimensional check per batch before shipping.
Specs
Materials and specifications
Materials
- PA12 (HP 3D HR PA 12) — default MJF material. ~48 MPa tensile, ~1,700 MPa modulus, 20% elongation. Biocompatible grade available.
- PA12 GB (glass beads) — ~30 MPa tensile but ~2,500 MPa modulus and better dimensional stability. Use for large flat parts and jigs.
- PA11 — bio-based, higher elongation (~45%), excellent impact resistance. For snap-fits and living hinges.
- TPU (Estane 88A) — flexible MJF for gaskets, grips, wearables, footwear midsoles.
Key specs
- Build volume
- 380 × 284 × 380 mm
- Layer height
- 80 µm
- Min wall thickness
- 0.5 mm (0.8 mm recommended)
- Min feature size
- 0.5 mm
- Dimensional accuracy
- ±0.3% (min ±0.3 mm)
- Surface finish
- Fine matte, Ra ~4–7 µm
- Colour
- Dark grey (native), black on dye
Case example
Typical case: 1,200-piece production run for consumer device
A hardware startup launched a consumer device and needed 1,200 outer housings for the first production batch. Injection tooling quoted €28,000 with 6-week lead time — unworkable for their launch window and cash-flow constraints.
We produced the batch across three MJF builds in PA12, dyed black, over 9 working days. Result: €9.80 per housing all-in, €11,760 total, no tooling capital, and design tweaks between batches at zero cost. They moved to injection at unit 5,000 once the design was locked.
Decision
When to choose MJF vs alternatives
- vs SLS: choose MJF when you need throughput at 100+ parts per build, tighter Z-axis strength and dark-grey/black is acceptable.
- vs FDM: choose MJF when the part needs isotropic strength, watertight walls or complex internal geometry FDM cannot handle.
- vs SLA/DLP: choose MJF when parts see mechanical load or repeated stress — SLA is too brittle for functional end-use.
- vs CNC machining: choose MJF when geometry is too complex to machine and batch size is 50–5,000 in nylon.
- vs injection molding: choose MJF for the first 1,000–3,000 units before tooling ROI, or for designs still iterating.
- vs metal 3D printing: choose MJF when the load case allows nylon — 6× lighter and 10× cheaper than titanium or steel.
Look at functional parts, short runs or spare parts on demand for use-case guidance, or send us the STEP file for review.
FAQ
MJF 3D printing FAQ
MJF is a powder-bed fusion process developed by HP. Instead of a laser, an inkjet head deposits a fusing agent (where the part should form) and a detailing agent (where it should not) across each layer. IR lamps then sweep the bed to melt the treated powder. The result is faster full-layer fusion, more consistent mechanical properties between the XY and Z axes, and a darker, finer surface than SLS. Same PA12 material family, different heat source and finer voxel control.
Get an MJF quote in 24 hours
Send us your STEP or STL and quantity. We check the geometry, propose the right nylon grade and confirm price and lead time.