What is MJF 3D Printing?
Multi Jet Fusion (MJF) is an Industrial 3D Printing developed by HP in 2016. It enables the creation of three-dimensional objects layer by layer from a 3D digital model. This technology creates unique parts and functional prototypes quickly and cost-effectively by using a Powder Bed Fusion. In the MJF process, the initial material, such as powdered nylon, is melted and consolidated through the use of infrared heat lamps and melting agents. The result is parts with high-quality finishes, detailed resolution and excellent mechanical properties. Because of its precision and strength, MJF 3D printing is widely used in applications requiring complex geometries and well-defined mechanical properties.
(Image Courtesy of HP)
Nylon PA12
The 3D Printed Material
Nylon PA12, also named polyamide 12, is one of the mainstays of this technology. Its high density, low porosity, excellent abrasion resistance, and durability make it suitable for a wide range of industrial applications. Nylon PA12 is a versatile thermoplastic that can be molded into wear-resistant parts, functional components, and reliable end user parts. Its strength and chemical resistance also make it an ideal material for parts that deal with challenging environmental conditions.
Advantages of MJF Printing
What advantages does MJF offer compared with other methods like Selective Laser Sintering (SLS), Fused Deposit Modeling (FDM), Stereolithography (SLA)?
HP Multi Jet Fusion (MJF)
HP Multi Jet Fusion (MJF) is one of the most commonly used 3D printing technologies for printing parts that are highly accurate and durable. Compared to its powder bed fusion counterparts like selective laser sintering (SLS), MJF prints are more cost-efficient at scale and produce less waste.
Selective Laser Sintering (SLS)
Selective Laser Sintering (SLS) is a 3D printing process that uses high-powered lasers to sinter, or bind, finely powdered material together into a solid structure.
This process is similar to MJF but finished SLS parts have a rough surface and are porous which allows moisture to infiltrate into the material. Additionally, they have low impact strength and are brittle. Lastly, because the print powder is subjected to high temperatures for it to sinter, this does mean that as it starts to cool it shrinks which can produce a dimensionally less accurate part than other additive manufacturing technologies. Depending on the design, the shrinkage rate can be as high as 3% to 4%.
Fused Deposition Modelling (FDM)
Fused Deposition Modelling (FDM), also known as the material extrusion additive manufacturing technique, utilizes polymers as the raw material (filament). The filament is usually heated to a molten state and then extruded through the nozzle of the machine (3D printer).
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The downside to this process is that the layers from printing are visible throughout the entire part and require rework and finishing that can alter the final dimensions and fitment, while not offering a high-end/high resolution looking finished product. Additionally, achieving consistent quality from print to print is challenging with this method.
Stereolithography (SLA)
Stereolithography (SLA) is one of the most widely used vat photopolymerization technologies. It creates objects by selectively curing a polymer resin, layer by layer, using an ultraviolet (UV) laser beam. The materials used in SLA are photosensitive thermoset polymers that come in a liquid form.
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Drawbacks for this method include final parts that are brittle and lack overall strength. The need for support structures during printing requires additional finishing that affects the finished look of the product. Lastly, the prints a prone to degrading and warping when exposed to sun and high temperatures.
