Multi Jet Fusion (MJF) 3D Printing

Do you need complex parts with highly accurate features and isotropic mechanical properties that can be produced quickly? Multi Jet Fusion (MJF) is an excellent choice for this common scenario. It can be used to produce functional prototypes and is ideal for bridge production as well as low to medium production parts.

How Does Multi Jet Fusion Work?

Multi Jet Fusion (MJF) is a 3D printing technology that uses powder bed fusion to produce highly accurate, functional prototypes and final parts.

MJF parts start with a thin layer of powder spread across the print bed. An inkjet array in the print carriage sweeps over the print bed, jetting two agents downward into the powder—a fusing agent and a detailing agent. The fusing agent is used to fuse the powder and the detailing agent is used to reduce fusing at the part boundary to achieve greater detail. After the print carriage finishes a pass, the build platform is lowered, more powder is added, and the process starts again.

Parts produced using MJF don’t require support structures, enabling the affordable production of complex geometries and multiple parts within a single build envelope.

Applications of Multi Jet Fusion

Parts with smooth surfaces and complex, intricate features can be manufactured using Multi Jet Fusion. Common applications include:

• • Functional prototypes
  • Rapid prototypes
  • Bridge production
  • Durable end-use parts
  • Housings
  • Complex and organic geometries
  • Parts with fine features
  • Parts with isotropic mechanical characteristics
  • Parts where a smooth surface is a must
  • Low- to medium-volume production parts

Industries where MJF parts are used include:

• Automotive
• Medical
• Consumer goods

What does MJF make possible?

Similar to injection molded parts: MJF can produce parts with a density similar to plastic injection molded parts. They can be processed and machined in similar ways. That makes MJF parts perfect for bridge production.

Print multiple parts in a single build: Because the powdered material serves as a support structure for the parts as they’re being fabricated, parts can be stacked in the Z direction, enabling you to get more parts out of each build.

Fine detail: MJF produces thinner layers than SLS and other 3D printing methods, which means MJF parts can incorporate finer detail than some other additive manufacturing techniques.

Affordable: Because of its superior printing speed, MJF is cost-effective for prototyping and low-production parts (up to about 1,000 pieces).

Advantages

Complex Geometries: MJF can be used to print highly detailed and dimensionally accurate parts. That makes it well-suited for producing functional prototypes and end-use parts with unique shapes.

Excellent Surface Finish: Because MJF uses a thin layer structure, it offers one of the smoothest surface finishes of any 3D printing technology.

Produce a Large Volume of Parts Quickly: Multiple parts can be produced at the same time in a single build.

Excellent Mechanical Properties: Parts produced using MJF have excellent isotropic mechanical properties.

Removable Build Volumes: Parts and their build platform can be removed from the printer for cooling. Meanwhile, another build volume can be installed so the printer can begin producing more parts. This unique design enables high-volume production of parts.

More Sustainable: Up to 80% of the powder from MJF prints can be recycled in subsequent prints, more than with SLS.

Disadvantages 

Limited Material Selections: Because MJF is a process that’s proprietary to HP, you’re restricted to their materials – Nylon 11 and 12.

Limited Color Options: Parts produced with MJF have a dark gray color, which limits your ability to recolor them.

Avoid Long & Thin Part Features: They are susceptible to non-uniform cooling, which may cause warpage.

Alternatives/What Can SLS be Paired With? 

MJF can be used for bridge production – ideal if you’re waiting for your injection mold tooling to be completed – and for small to medium-sized production runs. MJF can be used to quickly and affordably create functional prototypes for new product designs that will later be produced using injection molding.

With our cross-functional engineering expertise, we can help you tweak your part designs so they work well in both environments.

Alternatives to MJF:

• If isotropic mechanical properties aren’t a major priority for your parts, Selecting Laser Sintering (SLS) is a viable alternative.
• If you want parts that can be dyed or painted in a wider variety of colors, SLS or PolyJet may be better choices.
• If you want to choose from a wider variety of materials, SLS or FDM may be worth a look.

Traditional Technologies That Could Benefit from MJF 

Multi Jet Fusion can be used to build part designs that aren’t possible using traditional manufacturing methods such as CNC machining and sheet metal fabrication.

It also enables fast, low-cost production of prototype and limited-run production parts – without tooling.

MJF Materials Available

Nylon 11 and 12 are available for use with MJF printers. Not sure what you need? Talk to a Fathom expert today!

Check Out These MJF Printed Parts 

MJF Case Studies

Redesign of robotic assembly using MJF 

Fathom quickly produces MJF nasopharyngeal swabs for accelerated COVID-19 testing 

Finishing Option for MJF Parts 

AMT’s PostPro3D technology is a smart and automated post-processing solution for smoothing MJF printed parts. PostPro3D can achieve a high-quality surface finish that matches injection molding techniques when using 3D printing processes. This reduces lead time, cost of manufacture, operational and maintenance costs while providing the “missing piece” in the digital manufacturing chain.

Because MJF parts have a density that is similar to plastic injection molded parts, they can also be machined as needed. They can also be drilled to open up small holes that may be hard to produce during the printing process.

Why Choose Multi Jet Fusion? 

• It’s affordable. Other than FDM, MJF is one of the least expensive 3D printing technologies available. Its fast print time is also attractive if you need several hundred to a thousand parts quickly.
• MJF can be used for bridge production while you’re waiting for your production tooling to come online or if you’re not ready to commit to spending on a final production solution.
• It enables 3D printing of parts with fine details and complex geometries.

Why Choose Fathom’s MJF 3D Printing Capabilities? 

If you need short turnaround production, MJF machines are faster than many other types of additive processes. Fathom has MJF machine capacity available for Nylon 11 and 12. We can substitute other additive processes as needed and still ship on time. We are a single source for additive and other types of manufacturing.

In addition, Fathom offers domestic and overseas injection molding capacity that can help make your next project launch a success.

Get an MJF 3D Printing Quote

Quickly get a quote on your MJF project today with our SmartQuote platform.

Additional Resources

• • 3D printing vs. injection molding – breakeven analysis
  • Fathom additive manufacturing services
  • 3D printing materials
  • Design and engineering support
  • Rapid prototyping
  • Finishing and post-processing
  • U.S. plastic injection molding
  • China plastic injection molding

Nylon 12 is a commonly used thermoplastic that is strong enough for functional, small- to medium-size, prototyping and production parts. Nylon 12 is ideal for complex assemblies, housings, enclosures, and watertight applications. Achieve smooth surfaces and fine details with this durable material. Nylon 12 provides excellent chemical resistance to oils, greases, aliphatic hydrocarbons, and alkalis. Parts produced are a non-uniform light gray, but can be dyed a darker color for a uniform appearance.

Nylon 11 for MJF is also available upon request. Talk to a Fathom expert to learn more!

AMT PostPro3D Finishing / /

AMT’s PostPro3D technology is an automated post processing solution for smoothing 3D printed parts made with MJF. PostPro3D achieves a high quality surface finish that matches injection molding techniques when using 3D printing processes. This technology reduces lead-time, cost of manufacture, operational and maintenance costs while providing the ‘missing piece’ in the digital manufacturing chain. The PostPro3D machine makes 3D part surface finishing speed and cost competitive for high volume production.

Talk to an expert at Fathom today to take your parts to the next level using AMT PostPro3D for post processing.

MJF Parts and Images //

Advantages and Disadvantages of MJF 3D Printing //

Is MJF the right 3D printing technology for your next project? Learn more about the benefits and limitations of MJF below.

Advantages Include //

• Smooth Surface Finish // Parts will be perfectly smooth since MJF parts do not require extra support structures when printing parts with complex geometries. The unused powder in the powder bed acts as a support during printing. Parts are excavated from the powder bed after printing is completed. Excess powder is then shaken out and the part is ready for use. The result is a smoother surface with the possibility for crisp edges.
• Cost-Effective // Multi Jet Fusion can be cheaper than other additive manufacturing processes. Cost will depend on material choices and design complexity.
• Faster Turnaround // Multi Jet Fusion is a fast process. Parts can be printed quickly and put into use immediately.

Disadvantages Include //

• Limited material choices.
• Limited to small- or medium-sized parts.

Multi Jet Fusion vs. Selective Laser Sintering //

MJF and Selective Laser Sintering (SLS) both build parts out of a powder bed. SLS uses a powerful CO2 laser to sinter or fuse cross sections of the part. The platform shifts down one layer, powder is spread across the build platform, and the process repeats until the part has been made. The part is then excavated out of the powder bed after it has cooled.

MJF and SLS both use thermoplastic polymer powder material, however, there are a few key differences. The primary difference is the source of heat used during the process. SLS uses a powerful laser to heat each cross-section. MJF uses a fusing agent (ink) distributed onto the powder while an infrared light passes over the platform, curing the photosensitive ink that has fused with the powdered plastic. Fusing during MJF happens in a line while SLS fuses each cross-section point by point. The excess unused material in both technologies can be salvaged and recycled – but a greater amount is retrieved when using MJF. Post processing and finish can vary depending on the technology utilized. SLS parts are printed in white and then dyed. They may also be gray. MJF parts are printed in light gray and can be dyed black. Both technologies end up with a grainy finish, but can achieve a very smooth finish during post-processing.

Multi Jet Fusion Questions Answered //

Q // Who Invented Multi Jet Fusion?
A // Multi Jet Fusion was developed by Hewlett-Packard (HP).

Q // What Geometries Can Be Achieved With Multi Jet Fusion?
A // Parts that require internal cavities and complex geometries can be made using Multi Jet Fusion.

Q // What Color Options and Surface Finishes Are Available?
A // Parts produced are a non-uniform light gray and can be dyed in dark colors to achieve a uniform appearance. Choosing to dye parts will extend lead-time. These parts will feel grainy, similar to other power-based systems such as SLS, but can be smoothed further in post processing if desired.

Q // What Are Part Size Limitations?
A // The bounding box of the MJF 3D printing system is 284 mm x 380 mm x 380 mm (11.18 in. x 14.96 in. x 14.96 in.). Larger parts can be split and glued together during post processing.

Q // What Is The Standard Accuracy, Layer Height, and Minimum Feature Or All Size?
A // Expect an accuracy of +/-0.3 mm up to 100 mm or +/-0.003 mm per mm beyond 100 mm. The layer height is 80 microns. Fathom recommends a wall thickness minimum of 1 mm.

Q // What Is The Minimum Gap/Hole Size? Can You Tap Threads? What Is The Minimum Thread Size?
A // Minimum gap is typically 0.5 mm between features. Fathom suggests using threaded inserts for anything under ¼-20 threads when tapping threads.

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