What Is an MJF (Multi Jet Fusion)?

Multi Jet Fusion (MJF) is a powder bed fusion 3D printing process that builds polymer parts, most often nylon PA12, by jetting a fusing agent and a detailing agent onto each layer of powder, then exposing the layer to infrared energy. It is a close relative of selective laser sintering (SLS), which fuses the powder with a laser instead.

In short: MJF and SLS both turn nylon powder into functional parts. The difference is how each layer is fused.

How Does Multi Jet Fusion Work?

Each layer starts with a roller spreading fresh powder across the build platform. Print heads then apply two liquids:

• a fusing agent where the part should be, which absorbs infrared energy, and
• a detailing agent around the edges, which limits fusion so the outline stays sharp.

An infrared source then sweeps over the whole bed. The powder under the fusing agent heats up and sinters, and the untreated powder stays loose. The platform lowers and the cycle repeats. One published study gives a layer thickness of around 80 µm (0.003 in).

The key difference from SLS is that in MJF the heat source does not melt the polymer directly. Sintering starts when the fusing agent absorbs infrared energy. The process was introduced commercially in 2014. Under ISO/ASTM 52900 it belongs to powder bed fusion, in the subgroup that fuses with "agent and energy" rather than a scanning laser.

The range of certified MJF materials is still limited. One study lists PA12, PA11, glass-bead-filled PA12, polypropylene and TPU.

MJF vs SLS

	MJF	SLS
ISO/ASTM category	Powder bed fusion	Powder bed fusion
How each layer is fused	Fusing and detailing agents jetted onto the powder, then the whole layer is exposed to infrared	A laser scans each cross-section and sinters the powder inside its boundary
Typical layer	Around 80 µm (0.003 in) in one published study	100–180 µm (0.004–0.007 in) at NICE Rapid
Common materials	PA12, PA11, glass-bead-filled PA12, PP, TPU	PA12, PA11, glass-filled and carbon-filled PA12, TPU (NICE Rapid range)
Origin	Introduced commercially in 2014	Patented by Carl Deckard, University of Texas (filed 1986)
At NICE Rapid	Not among our in-house processes	In-house, ±0.2 mm (±0.008 in), 2–3 day lead time

Choosing Between MJF and SLS

For most functional nylon parts, such as housings, brackets, snap fits and assemblies, the two processes are alternatives, and the choice comes down to material, availability and lead time. Keep these points in mind:

• Specify the material and properties, not only the process. If a drawing says "MJF PA12," check whether the requirement is really a PA12 nylon part with certain mechanical properties. An SLS PA12 part may meet the same need.
• Mind build orientation. Studies disagree on how much print orientation affects MJF tensile properties. One study found that vertically oriented parts performed better because they received more infrared sweeps. Agree on orientation for load-bearing parts.
• Accuracy is a trade-off. One dimensional-accuracy study found that the settings giving the best geometric accuracy also increased interlayer porosity. Confirm critical dimensions with a sample.

NICE Rapid does not list MJF among its in-house processes. For functional nylon parts, our comparable in-house process is SLS 3D printing.

Frequently Asked Questions

What is MJF 3D printing?

MJF (Multi Jet Fusion) 3D printing is a powder bed fusion process that jets a fusing agent and a detailing agent onto each layer of polymer powder, then fuses the treated areas with infrared energy. It is mainly used for functional nylon parts.

What is the difference between Multi Jet Fusion and SLS?

Both build parts from polymer powder in a powder bed. SLS uses a laser to sinter each cross-section directly. MJF jets fusing and detailing agents onto the powder and uses an infrared source that sweeps the whole layer, so sintering starts where the agent absorbs the energy.

What does MJF mean?

MJF stands for Multi Jet Fusion, a powder bed fusion 3D printing process introduced in 2014. The name refers to the jetted agents that define where the powder fuses. It is mostly used with nylon PA12, plus a few other thermoplastics such as PA11, polypropylene and TPU.

Related Services at NICE Rapid

• 3D Printing — MJF is not on our list, but we run SLS in-house in PA12, PA11, glass-filled and carbon-filled PA12 and TPU, the comparable route to functional nylon parts.
• Rapid Prototyping — our engineers recommend the best in-house process for your part, timeline and material.
• Request a Quote — send your file and your nylon part requirements, and we will confirm whether SLS meets them.

Sources

1. Lee & Kajtaz, "Experimental Characterisation and Finite Element Modelling of Polyamide-12 Fabricated via Multi Jet Fusion," Polymers — MJF differs from SLS through fusing and detailing agents and a sweeping planar infrared source; the fusing agent absorbs IR and the detailing agent inhibits fusion; the powder "is not melted or sintered directly by the heat source"; "general disagreement" in the literature on orientation effects; vertical orientation favored tensile properties due to more IR sweeps — pmc.ncbi.nlm.nih.gov
2. Adach et al., "Study on Geometry, Dimensional Accuracy and Structure of Parts Produced by Multi Jet Fusion," Materials — MJF introduced in 2014; powder applied with a roller; layers "around 80 microns"; access to certified MJF materials "still limited": PA12, PA11, PA12 with glass beads, PP and TPU; the parameters giving the highest accuracy also caused interlayer porosity — pmc.ncbi.nlm.nih.gov
3. Koltsaki et al., "A Comprehensive Overview of Additive Manufacturing Processes Through a Time-Based Classification Model," 3D Printing and Additive Manufacturing — ISO/ASTM 52900 powder bed fusion includes "systems that perform fusion with agent and energy, like Multi Jet Fusion (MJF)" — pmc.ncbi.nlm.nih.gov
4. US Patent 4,863,538 (C. R. Deckard; assignee University of Texas System), Method and apparatus for producing parts by selective sintering (filed 1986) — SLS laser sinters "only the powder within the boundaries of the cross-section" — patents.google.com
5. Perez-Barcenilla et al., "Applicability of a Material Constitutive Model Based on a Transversely Isotropic Behaviour for the Prediction of the Mechanical Performance of Multi Jet Fusion Printed Polyamide 12 Parts," Polymers — MJF is a powder bed fusion technique for thermoplastic powders, "primarily focusing on polyamide 12 (PA12)" — pmc.ncbi.nlm.nih.gov