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MJF vs. FDM: What you need to know

The additive manufacturing industry is older than many people think. In fact, roughly the past 40 years are peppered with significant advances in 3D printing. Engineers started using stereolithography (SLA) technology for manufacturing prototypes in the 1980s and use of fused deposition modeling (FDM) quickly followed in the early 1990s. Fast forward to 2016, Multi Jet Fusion (MJF) hit the market and transformed the additive manufacturing industry yet again.

 

FDM is one of the oldest 3D printing technologies, and MJF is among the youngest, but both can quickly produce accurate parts. Which is best for your next project? Here’s what you need to consider before you make a final decision.

What is MJF 3D printing?

HP’s expertise in inkjet printing technology and precision mechanics informed the company’s 2016 foray into the 3D printing sector. MJF technology builds parts up layer by layer in a bed of powder material to create strong and accurate components with fine details, consistent mechanical properties, and quality surface finishes.

 

Capable of producing 100% filled, functional, and detailed parts that don’t require support structures, MJF is suitable for creating robust prototypes or low-volume production runs. Popular applications include jigs, fixtures, electronic housings, and mechanical assemblies.

How does Multi Jet Fusion work?

At the beginning of the Multi Jet Fusion 3D printing process, your engineer will place the moveable build unit in the printer, and the printer will deposit a layer of powder material, such as polyamide 11 (PA 11), polyamide 12 (PA 12), or TPA. Then, the printing and fusing carriage will move across the build area, and the inkjet nozzles will apply fusing agents. Once the layer is complete, the build unit will retract, the machine will deposit another layer of powder, and the process will repeat. Once the print is complete, the operator will then remove the build box, cool and separate the part from loose powder, and use a bead, air, or water blaster to remove any leftover powder.

What are MJF 3D printing’s advantages and disadvantages?

MJF is up to 10 times faster than other 3D printing technologies, making it well-suited for rapid prototyping and mid-sized batches of end-use parts. Support structures aren’t required, which means you can save on materials and reduce production time. Plus, since MJF printers can print ultra-thin layers, you can produce dense parts with low porosity, high resolution, good mechanical properties, and consistent strength in all directions.

 

However, the technology is more expensive than some other additive manufacturing technologies, and it’s only compatible with a few materials.

What is FDM 3D printing?

FDM is cost-effective and offers a range of printer sizes. It is ideal for printing during the initial concept development and mid-fidelity prototyping phases to gain a general idea of how your final part will look, feel, and fit with other components. FDM can also be used for end-use products.

How does FDM printing work?

Creating a part using FDM requires a printer, a digital model, and a spool of filament. Acrylonitrile butadiene styrene (ABS), acrylonitrile styrene acrylate (ASA), polycarbonate (PC), and nylon (PA) are among the most popular filament materials.

 

After slicing your digital 3D model, your printer will melt and extrude the plastic filament from a nozzle as it moves along the X, Y, and Z axes. The build platform will move down (or the extrusion head will move up) after each layer, and the process will begin again. Most layers are 0.1 mm to 0.5 mm tall, but you may need to use smaller layer sizes if you need smoother surfaces, a curved print, or a high level of detail.

What are FDM 3D printing’s advantages and disadvantages?

FDM has lots to offer, from fast turnaround times to compatibility with a wide range of materials and colors. When using an FDM printer, you can use ABS, nylon, and more to create strong and functional prototypes or end-use parts. Industrial FDM machines have build sizes as large as 1,000 mm x 1,000 mm x 1,000 mm, and you can just as easily print a custom part as you would a mass-produced part.

 

Close up of FDM printer

 

FDM also has a few drawbacks. For one, it doesn’t offer the same quality, reliability, or dimensional accuracy that other 3D printing technologies do. Nozzles can clog up, or print beds can become miscalibrated, causing failed prints. Like with MJF, if your part cools at different rates, you may notice warping. You might also see visible layer lines and lower resolutions.

 

Additionally, FDM parts are anisotropic and often require support, so you’ll need to consider orientation and support structure placement while designing your part. You may also need to post-process your parts via sanding, polishing, acetone vapor smoothing, or epoxy coating or choose a more expensive dissolvable support material.

Multi Jet Fusion vs. Fused Deposition Modeling

When comparing FDM vs. MJF, each process has pros and cons, and there are certain situations where it makes sense to use one over the other. You need to consider:

 

  • Your part quality: If you’re creating a simple prototype, you should use FDM. However, if you need an end-use part with a smooth, high-quality, consistent finish, opt for MJF and avoid additional post-processing.

 

  • Your part’s desired strength, durability, and other properties: While MJF prints are nearly isotropic, FDM prints are weaker in the Z dimension due to the heat and stretching from the extrusion process. Additionally, MJF parts are often stiffer, denser, and more durable than FDM parts, so if you need a long-lasting functional part, consider using MJF. If you need a conceptual prototype, use FDM to reduce costs.

 

  • Your design’s complexity: MJF doesn’t require support structures and uses smaller layers, so you have more design flexibility and the ability to print more complex structures.

 

  • Your part’s material: MJF is only compatible with a few materials, so you should opt for FDM if you want a wider selection of material and color options.

 

  • Your production requirements: If you need to produce several functional parts or have a tight turnaround time, you should consider MJF. MJF machines can print around 300 cm3 per hour, compared to FDM’s average production speed of 10 cm3 per hour. Plus, you can more effectively use your print volume to scale production.

 

  • Your environmental impact: Since an FDM print can use 20% of its material in its support structures, FDM has the largest waste of all 3D printing technologies. MJF has a relatively low environmental impact because around 85% of MJF powder can be recycled.

3D print with Fast Radius

MJF and FDM both offer relatively short turnaround times and quality parts. When deciding between the two, you need to consider production requirements, environmental goals, and the desired part quality, complexity, material, and properties.

 

If you’re unsure whether you should use MJF or FDM, Fast Radius’ experts can help you choose the technology that best suits your project. We can also optimize your design and produce your parts using industrial-grade printers and materials. Contact us today to get started.

 

Visit our resource center for more information about additive manufacturing, including the importance of layer height, 3D printing costs, and more.

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