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Multi Jet Fusion (MJF) – 3D Printing Simply Explained

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by David Pechter
Nov 8, 2018

The new industrial-strength power in additive manufacturing is here: HP's Multi Jet Fusion. Take a look at how it works and why it's a game-changer for 3D printing.

Multi Jet Fusion Behind the Technology

Powder bed printing.
Powder bed printing. Source: Wikipedia

Want to 3D print hundreds of parts? Multi Jet Fusion (MJF) can get you there. Like its competitor HSS from Voxeljet, MJF is a mash-up of two older powder bed technologies: SLS and binder jetting. In general, powder bed printing eliminates the joys of FDM, like manually removing a brim, scraping a build plate, or squeezing glue stick.

Binder jetting has applications from full-color prototypes to sand-casting molds. It has, by its nature, two components: a printed adhesive, or binder, and a powder substrate, such as sand or gypsum. The geometry of the part comes from the pattern of jetted binder sprayed onto successive layers of powder.

Selective laser sintering, or SLS, also starts out with a powder, but instead of jetted adhesive, a pulsed laser sinters tiny volumes (or voxels) of nylon powder together. Where the laser fires, a voxel is added to the part. Millions of voxels are laser-sintered together from successive layers of powder to form the part.

Multi Jet Fusion HP's New Digital Manufacturing Vision

Layers of gears produced using MJF.
Layers of gears produced using MJF. Source: static1.squarespace.com

MJF does powder bed one better and is a natural move for HP, with its heavy-duty 2D printing know-how. The new process has the speed and technologies of a printing press, as its print head and heater arms sweep across the full print area for each layer of the part.

Like binder jetting, MJF uses inkjet printing to define part geometry, but then it diverges in how it fuses the powder into a part. Each fraction of a millimeter layer is created with three steps:

  1. A layer of powder is spread across the bed.
  2. Inkjet print heads sweep across the powder, depositing millions of drops of light-absorbing ink. These define which voxels to keep and which will fall away as powder. Additional inks help mark a crisp part boundary and can provide other properties, including color.
  3. An infrared heater sweeps across the bed. The ink-marked areas absorb enough of the IR energy to sinter to the underlying part, and the rest remains as full-color powder.

Multi Jet Fusion No Supports Necessary

The freedom of powder.
The freedom of powder. Source: multistation.com

Powder bed printing stands out from FDM because, instead of generated structures, the underlying powder supports the part.

On the other hand, one benefit of FDM is lost: In MJF, you can’t print a sealed hollow volume. Any such space will be filled with powder. As such, drain openings are required.

But for most prints, that’s a small price to pay for the ability to create any unsupported shape with overhangs. No secondary processing is required to dissolve or remove supports. This also means that real bulk processing without a lot of manual work is possible.

Multi Jet Fusion Pros & Cons – MJF vs FDM and SLS

MJF offers color printing
MJF offers color printing Source: HP

Pros:

  • Quality full-function parts with more design flexibility than FDM
  • Lowest cost 3D printed parts ready for use in production designs
  • Faster overall cycle times than SLS
  • Higher percentage of powder recycled than SLS
  • Denser use of build area for nested parts vs FDM
  • Scalable to hundreds or thousands of parts
  • Color printed parts (using some HP Fusion printers)

Cons:

  • Limited to just two nylons (vs a wide range of materials in FDM)
  • Limited to two colors, gray and black, on an industrial scale
  • Large and expensive machines
  • Not home friendly

Multi Jet Fusion Setting the Bar for Industrial 3D Printing

Industrial scale 3D printing.
Industrial scale 3D printing. Source: pace.it

So why is Multi Jet Fusion a game-changer?

HP MJF…

  • builds on the advantages of powder bed 3D printing for industrial use.
  • offers the lowest part cost of any 3D printing technology.
  • produces high-quality parts.
  • eliminates manual steps and scales for small production runs.
  • offers the flexibility of fusion and detailing agents to add new material properties.
  • brings the name recognition and manufacturing clout of HP to 3D printing.
  • introduces HP’s Open Platform for new material certification.

MJF is already supported by a range of printers, including the color-capable HP 300/500 series as well as the production-scale 4200 and 4210 printers. With HP’s recent release of a binder jetting metal printer, Metal Jet, they are making it clear that MJF is part of larger HP strategy for additive manufacturing. The era of supposed 3D printing hype is over… the additive era of manufacturing is here.

Given that these machines targeted at industries, it’s not unusual that you wouldn’t have access to one. If, however, you still want to have something printed using the technology, consider a 3D printing service. To find the best one for your needs, check out our Price Comparison Service. We provide real-time quotes from the most popular companies, including Shapeways, i.Materialise, and Sculpteo:

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License: The text of "Multi Jet Fusion (MJF) – 3D Printing Simply Explained" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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