MJF: Multi Jet Fusion
Quick answer
MJF is HP's powder-bed fusion process: inkjet arrays print fusing and detailing agents onto nylon powder, and an infrared lamp fuses the printed areas. It produces PA12, PA11 and glass-bead-filled parts with fine detail, consistent properties and fast layer times — the main alternative to SLS for production nylon parts.
How MJF works
Each layer starts as a fresh bed of nylon powder. A carriage carrying inkjet heads sweeps the bed and deposits two liquids: a fusing agent wherever the part's cross-section should melt, and a detailing agent around its edges to keep boundaries sharp. A second carriage exposes the bed to infrared energy; only the agent-treated powder absorbs enough energy to fuse. Because fusing happens across the whole layer at once, layer time does not depend on how much of the layer is part — a key difference from laser-based SLS.
Materials
HP's nylon range is built around reusability: unfused powder is recovered and used again at a manufacturer-specified refresh ratio. The flagship grade is HP PA 12, the balanced standard; the range also includes a PA 11 grade where ductility and impact resistance matter, and a glass-beads grade for stiffer, more dimensionally stable parts. HP's current datasheets for those two grades could not be re-verified at this site's publication date, so — per our sourcing policy — only PA 12 carries a data page for now; the others will be added when their datasheets are verified.
Strengths and limits
- Strengths: fast, content-independent layer times; fine features and sharp edges from the detailing agent; consistent, near-isotropic properties; a streamlined powder-recovery workflow, especially with HP's processing stations.
- Limits: parts emerge grey and are usually dyed black, so colour work is less flexible than SLS; the material catalogue is narrower than SLS (one machine maker, a focused material set); hollow parts still need escape holes, as covered in the design guide.
SLS or MJF?
The two processes overlap heavily in applications. The detailed, sourced comparison — mechanics, materials, colour, economics — is at SLS vs MJF. A third powder-bed option, Stratasys's SAF, pursues similar production goals with a single-fluid approach on the H350.
Frequently asked questions
What materials does MJF print?
HP's nylon range for MJF is the High Reusability family: PA 12 as the standard, PA 11 for ductility, and PA 12 Glass Beads for stiffness and dimensional stability. PA 12 has a full page in the material database with HP datasheet values; the PA 11 and glass-beads datasheets are being re-verified before their values are published here.
Is MJF faster than SLS?
Per layer, yes in most cases: MJF fuses a whole layer in a fixed number of passes regardless of how many parts it contains, while SLS laser time scales with cross-section area. Whole-job turnaround also depends on cooling and post-processing, which both processes share.
What colour are MJF parts?
Raw MJF parts come out grey because of the fusing agent; they are very commonly dyed black for a uniform finish. SLS parts, by contrast, are white or off-white and accept dye in a wide range of colours.
Does MJF need supports?
No. Like SLS, the powder bed supports the parts, so MJF prints complex geometries and nested builds without support structures.
Last updated: November 2026