September 23, 2020
multi jet fusion mjf 3d printing guide cover

Multi Jet Fusion: Everything You Need To Know About MJF 3D Printing

Pioneered by HP, one of the most valuable 3D printing companies, and boasting performance numbers never previously seen in 3D printing, it’s no wonder Multi Jet Fusion has been adopted so quickly. HP’s new 3D printing technology is scalable, prints fast, and can print in full color — what’s not to like?

In this guide, we explain the details behind the MJF process, how it works, compatible materials, it’s applications, and all advantages and disadvantages over other technologies such as selective laser sintering and binder jetting.

This guide is also part of our FREE 3D printing technologies EBook. You can download it here.

Multi Jet Fusion 3D Printing Process

Multi Jet Fusion is unique in that it doesn’t just involve a 3D printer, but features a wheelable build unit that slots into the printer to print on. When you add the processing station to cool parts fast, that makes three different parts used in Multi Jet 3D printing.

Once the built unit has been inserted into the 3D printer, you can start printing. HP offer their own 3D printer software that helps with printing by efficiently packing the build chamber to make the best use of the printing material.

multi jet fusion printing process mjf
An infographic explaining the Multi Jet Fusion Printing Process. Credit: additive.blog.

Once printing has commenced, a layer of build powder is applied over the print area. A fusing agent is then applied on the dimensions for the print to be solidified. This is very similar to binder jetting in that the fusing agent improves heat absorption — meaning that area will solidify under the heat while the rest of the material is unaffected.

A detailing agent is applied simultaneously around the edges of the part to be printed. This helps create sharper surface finishes with more detail on the boundaries.

multi jet fusion 3d printed part
A part created with Multi Jet Fusion. Note the lack of supports necessary and the resulting smooth surface finish.

The build area is then heated, so that the intended areas solidify — while the other areas remain in powder form. Multi Jet Fusion is faster than SLS 3D printers as the heat source scans the whole layer at once, rather than tracing the area via a single point. This is repeated, layer by layer, until the print is finished.

This may sound similar to SLS 3D printing, and it is. The process is similar to Selective Laser Sintering, though instead of using a laser to sinter the part, MJF uses these ink agents to solidify the part using infrared.

Multi Jet Fusion Materials

One of the few drawbacks of Multi Jet Fusion is the lack of variety of materials available to print with. HP’s Jet Fusion 300 and 500 3D printers can only print Nylon PA12, with other printers only able to print TPU, PA11 and PA12.

Nylon is a fantastic printing material with engineering grade properties, so being restricted to just Nylon isn’t the worst possible situation. You’re still able to create great prints with strong mechanical properties. But still, other 3D printing technologies like Fused Deposition Modeling offer far more 3D printer filament options and versatility.

hp jet fusion 300 and 500 3d printers
HP 3D printers like their Jet Fusion 300 and 500 models are limited to just PA12 Nylon parts.

As with SLS, Multi Jet Fusion does not require supports while printing, in contrast to technologies like FDM or SLA. This is because the part rests on the surrounding powder and therefore is not deformed by gravity.

As a result, MJF parts never have ‘scars’ from support removal, and have some of the smoothest surface finishes of any 3D printing technology. This also saves on material costs for supports.

Multi Jet Fusion Applications

Rapid prototyping: Though prototypes can be created with any 3D printing technology, MJF can create strong prototypes with good mechanical properties to really test function and form.

Low volume production: HP’s Multi Jet 3D printers’ scalability means MJF is a real contender to take low volume manufacturing away from other production methods. This is especially true for very complex parts with intricate parts, such as casings and delicate pipe parts.

multi jet fusion prototype production
Multi Jet Fusion is perfect for iterative testing of prototypes and low volume production.

Compete with injection molding for manufacturing contracts: MJF is the first 3D printing technology to be considered a viable competitor for injection molding. Though it cannot compete on large scale production, at lower numbers Multi Jet Fusion can be considered a real alternative to injection molding, especially since it can create full color parts, and stronger parts that with injection molding.

Advantages and Disadvantages

Multi Jet Fusion Advantages

  • Cheap cost per part: Multi Jet Fusion has some of the lowest per part costs of any 3D printing technology, though it is not as accessible as an FDM 3D printer.
  • Fast printing process: MJF is faster than Selective Laser Sintering as it heats a whole layer at once, rather than tracing each area.
  • More environmentally friendly: With SLS 3D printers you usually get around 50% material good enough to reuse after a print. MJF is far better than this, and is aided by the processing station which sucks excess material back in to the printer to be reused, and can also clean prints. Less wasted plastic powder means less environmental damage.
  • Ability to print color parts: Whereas technologies like Stereolithography can only print a few block colors, HP offer a range of printers that can print in full color. This eliminates the need to paint or dye the print after printing.
  • Very smooth surface areas: the Multi Jet Fusion printing process creates crisper edges than technologies such as Selective Laser Sintering, so often MJF parts will appear smoother.

Multi Jet Fusion Disadvantages

  • Limited material options: HP 300 and 500 3D printers can only print with Nylon PA12, while other printers can only use PA12, PA11 and TPU. For those who need a versatile range of 3D printer materials, this creates problems.
  • Very expensive 3D printers: With these industrial 3D printers you’re unlikely to spend less than $50,000 – $70,000. This represents a lot of cost upfront before any benefits are realized.