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 printers are significantly cheaper and more accessible than MJF printers; MJF printers are more of an industrial printing solution. A typical FDM printer is shown in the image below:
A typical FDM printer.
Image Credit: Shutterstock.com/Ja Crispy
What Are the Advantages of FDM Compared to MJF?
Listed below are some key advantages of FDM vs. 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).
What Are the Disadvantages of FDM Compared to MJF?
Listed below are some key disadvantages of FDM vs. 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. The image below shows an MJF printer:
Image Credit: https://3dprint.com/wp-content/uploads/2020/09/hp-jet-fusion-5200-3d-printer-front-view-1.jpg
What Are the Advantages of MJF Compared to FDM?
Listed below are some key advantages of MJF vs. 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
What Are the Disadvantages of MJF Compared to FDM?
Listed below are some key disadvantages of MJF vs. 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.
50 to 500 microns
Wide range of material colors
Minimum feature size
Parts must cool down after printing
Can produce high-strength parts
Has isotropic material properties
Minimum wall thickness
Parts need support structures
Largest print volume
370 x 274 x 375 mm
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.
FDM vs. MJF: Technology Comparison
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.
FDM vs. MJF: Material Comparison
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.
FDM vs. MJF: Product Applications Comparison
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.
FDM vs. MJF: Print Volume Comparison
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.
FDM vs. MJF: Surface Finish Comparison
FDM parts have a poor surface finish and require post-processing to improve this. MJF parts have a slightly rough matte surface finish that has the appearance of a sand-cast part. MJF parts can be dyed with a black dye to give a uniform finish, as the parts come out of the printer with an uneven gray color.
FDM vs. MJF: Cost Comparison
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.
What Are the Mutual Alternatives to FDM and MJF?
Despite the benefits of FDM and MJF, there are alternative technologies that can achieve similar results:
- Polyjet: Polyjet printing works by spraying photopolymer drops onto a build plate. A UV light then passes over these droplets to solidify the layer. The next layer is then deposited on the top of the previous one until the part is complete. Polyjet printers have extremely high resolution. They can print parts from many different materials, with different properties and colors in the same part. MJF printers use liquid photopolymers instead of powder-like source materials. An inkjet type head deposits these photopolymer droplets similarly to how the MJF printer deposits its fusing and detailing agents.
What Are the Similarities Between FDM and MJF?
Listed below are some of the similarities between FDM and MJF:
- Both MJF and FDM can only produce plastic parts. However, specialized FDM filaments have a metal powder in a polymer matrix that needs to be post-processed in a furnace to achieve a truly metal part.
- Both MJF and FDM use heat to bond plastic together to produce final parts
What Are the Other Comparisons for FDM Besides MJF?
Listed below are the comparisons for FDM besides MJF:
- FDM vs. SLS: Selective laser sintering also manufactures parts from thermoplastics using heat. SLS prints almost exclusively in polyamides, whereas FDM has a much wider range of material options. SLS also melts the plastic with a laser instead of a heated nozzle. SLS printers can produce much higher quality parts when compared to FDM printers. For more information, see our article on SLS vs. FDM.
What Are the Other Comparisons for MJF Besides FDM?
Listed below are the comparisons for MJF besides FDM:
- MJF vs. SLA: Stereolithography is a printing process that also uses a UV light source to polymerize a photopolymer. SLA can produce parts with higher quality surfaces when compared to parts made using MJF.
This article summarized the differences between FDM and MJF 3D printing technologies.
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