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Powder bed fusion

What is MJF and how does it work?

A fast, accurate powder bed technology that fuses powder with jetted agents and heating lamps instead of a laser.

Tell us about your project▶ Step-by-step process

Multi Jet Fusion

In MJF, developed by HP, inkjet heads deposit two agents on the powder layer: a fusing agent that marks the area to be fused and a detailing agent that sharpens the edges. An infrared lamp then passes over the layer and only the treated areas fuse. Because the whole layer is processed in a single pass, it is faster than SLS and gives a more uniform surface. A similar method, SAF (Selective Absorption Fusion), uses a single absorbing fluid and infrared heat instead of a laser.

Typical values
Typical tolerance±0.3% (lower limit ±0.2 mm)
Layer thickness80 µm
Minimum wall thickness0.5 – 1 mm
SurfaceMatte grey; more uniform than SLS
SupportsNot required

Process

MJF step by step

  1. 01

    A powder layer is spread (typically 80 µm).

  2. 02

    Heads jet the fusing and detailing agents.

  3. 03

    An infrared lamp passes over the layer; treated areas fuse.

  4. 04

    The process repeats; the build unit is cooled in a cooling station.

  5. 05

    Parts are separated from the powder, bead blasted and usually dyed black.

Advantages

  • Faster than SLS with a more uniform surface
  • No supports needed
  • Low unit cost in series production
  • High repeatability

Limitations

  • Color usually grey/black
  • Limited material choice (PA12, PA11, TPU, PP)
  • Risk of warping in thick sections

Best suited for

  • End-use nylon parts
  • Enclosures and clips
  • Orthotic and prosthetic parts
  • Series production

Design

MJF design guidelines

  • Minimum wall thickness0.5 – 1 mm
  • Smallest detail0.5 mm
  • Minimum hole diameterØ 1 mm
  • Overhang angleUnlimited
  • Clearance for moving parts0.4 – 0.6 mm
  • Text and logosEmbossed ≥ 1 mm
  • Escape holeØ 5 mm powder escape hole

Design guidelines for all technologies →

Surface and assembly

Post-processing

  • Bead blasting
  • Black dyeing
  • Vapor smoothing

Materials

Materials printed with MJF

Good to know

Frequently asked questions about MJF

What is MJF?

In MJF, developed by HP, inkjet heads deposit two agents on the powder layer: a fusing agent that marks the area to be fused and a detailing agent that sharpens the edges. An infrared lamp then passes over the layer and only the treated areas fuse. Because the whole layer is processed in a single pass, it is faster than SLS and gives a more uniform surface. A similar method, SAF (Selective Absorption Fusion), uses a single absorbing fluid and infrared heat instead of a laser.

How does MJF work?

A powder layer is spread (typically 80 µm). Heads jet the fusing and detailing agents. An infrared lamp passes over the layer; treated areas fuse. The process repeats; the build unit is cooled in a cooling station. Parts are separated from the powder, bead blasted and usually dyed black.

What applications is MJF suitable for?

MJF is especially suitable for end-use nylon parts, enclosures and clips, orthotic and prosthetic parts, series production.

How accurate are MJF parts?

Typical tolerance is ±0.3% (lower limit ±0.2 mm). The exact value depends on the machine, material and part geometry.

Other technologies

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