FDM vs. MJF: Differences and Comparison
Learn about the differences between these two 3D printing technologies.
FDM (Fused Deposition Modeling) is a 3D printing technology that builds parts by extruding a melted thermoplastic filament onto the build plate one layer at a time. MJF (Multi Jet Fusion) is a powder bed fusion technology that fuses thermoplastic particles with heat. MJF has much higher production speed, part quality, and mechanical properties, whereas FDM has a wider range of materials available in many different colors and is significantly cheaper. FDM is ideally used for one-off low-fidelity parts. MJF, on the other hand, is better suited to low-volume production of functional products.
This article will compare FDM vs. MJF in terms of their differences, materials, and printing technology.
FDM Definition and Comparison to MJF
Fused deposition modeling was first developed and commercialized by Scott Crump in 1988. The process involves guiding a thin filament of thermoplastic through a heated nozzle/hot end. The plastic exits the nozzle and is placed on the build plate in the pattern of the part cross-section. Once a layer is complete, the print nozzle moves up one layer and deposits the plastic on the previous layer until the part is complete.
FDM printing is usually significantly cheaper and more accessible than MJF printers; MJF printers are more of an industrial printing solution.
For more information, see our article on FDM 3D Printing.
Advantages of FDM Compared to MJF
- FDM printers are significantly cheaper than MJF printers
- FDM printers can make use of materials from multiple different suppliers. MJF materials, on the other hand, can only be bought from HP (Hewlett Packard).
Disadvantages of FDM Compared to MJF
- FDM printers produce parts with poor surface finishes
- FDM printed parts have anisotropic material properties in the z-direction. This is due to poor interlayer bonding.
MJF Definition and Comparison to FDM
MJF (Multi Jet Fusion) is a powder bed 3D printing technology. It was developed by HP in 2016. MJF works by employing a multi-step process. A powder is first applied in a thin layer on the print bed. The powder is then heated to just beneath its sintering temperatures. Next, a fusing agent is applied to the powder in the shape of the part cross-section. A detailing agent is also applied to the outer edges of the part to help create crisper and sharper edges. A heat source then passes over the plastic and sinters the plastic particles together wherever the fusing agent is applied. MJF is a more advanced technology. It is specifically geared towards high production when compared to FDM.
MJF printers can produce highly accurate parts. They also have a significantly quicker print time when compared to FDM printers.
To learn more, see our guide on What is MJF.
Advantages of MJF Compared to FDM
- MJF allows for multiple parts per print. It can make more efficient use of the entire build volume due to build-packing techniques.
- MJF parts have isotropic material properties
Disadvantages of MJF Compared to FDM
- MJF printers are some of the most expensive 3D printers available. They are significantly more expensive than even the most advanced FDM printers.
- MJF parts have very limited color options and can only be dyed black. FDM printers can print parts in a wide array of colors.
| Attribute | MJF | FDM |
|---|---|---|
Attribute Print resolution | MJF 80 microns | FDM 50 to 500 microns |
Attribute Wide range of material colors | MJF No | FDM Yes |
Attribute Minimum feature size | MJF 0.25 mm | FDM 1 mm |
Attribute Parts must cool down after printing | MJF Yes | FDM No |
Attribute Can produce high-strength parts | MJF Yes | FDM Yes |
Attribute Has isotropic material properties | MJF Yes | FDM No |
Attribute Minimum wall thickness | MJF 0.5 mm | FDM 1 mm |
Attribute Print speed | MJF 300 cm3/hour | FDM 10 cm3/hour |
Attribute Parts need support structures | MJF No | FDM Yes |
Attribute Largest print volume | MJF 370 x 274 x 375 mm | FDM 1000 x 1000 x 1000 mm |
Table. FDM vs. MJF
MJF parts are high-strength and have better surface quality when compared to FDM parts. MJF can also print significantly faster. FDM printers are cheaper with a wider range of available materials.
Our Senior Solutions Engineer, Matt Schmidt says, ""Both FDM and MJF are great platforms for both prototype and production. MJF prices are often very competitive with FDM and offer better mechanical part properties, production costs and surface quality, while FDM can offer a wider material selection, greater part size capability and colors. They are very different platforms and the decision is often based upon each platforms unique build capabilities mentioned previously and whether they fit the customers need. Cost could be a non-factor if the part does not meet a cosmetic need for example."
Common Comparisons Between FDM and MJF
Technology
FDM and MJF technologies are very different. The first FDM machine was developed in the 1980s and the fundamental technology has not changed. MJF printers were developed in 2016 and have employed some advanced techniques. FDM printers simply extrude a melted thermoplastic onto the build plate. Whereas MJF makes use of a multi-step process that starts by laying down a thin layer of plastic powder. Then a detailing and fusing agent is applied. Finally, a heat source fuses the material together.
Material
FDM printers can make use of a wide range of rigid and flexible, multi-color thermoplastics. An MJF printer, on the other hand, can only make use of a handful of materials such as nylon, polypropylene, and TPU (Thermoplastic Polyurethane). It must be noted that MJF can produce stronger parts than FDM printers.
Product Applications
FDM printed parts can be successfully used for a wide range of applications. Examples include: functional and visual prototypes, as well as, limited production runs on mechanical components. MJF parts are stronger and tougher than FDM equivalents. These items can be used for low-volume functional parts as an alternative to injection molding, which is often too expensive to justify low production volumes.
Print Volume
FDM printers can have much larger build volumes than MJF printers. However, it must be noted that MJF printers make more efficient use of the available print volume. This can be done by efficiently stacking parts within the entire volume.
Surface Finish
FDM printers can have much larger build volumes than MJF printers. However, it must be noted that MJF printers make more efficient use of the available print volume. This can be done by efficiently stacking parts within the entire volume.
Cost
MJF printers are an industrial manufacturing solution and as such are orders of magnitude more expensive than even the most capable FDM printer. A top-range FDM printer can cost approximately $6,950 whereas MJF printers start at $270,000. You can source both FDM and MJF parts easily from Xometry's 3D printing service, though, so get your quote today!
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