What is HP's Multi Jet Fusion (MJF) 3D printing?

Today, designers and engineers have numerous options for 3D printing materials and technologies. This article highlights Multi Jet Fusion (MJF), HP's exclusive 3D printing technology, which is a practical solution for intricate and industrial applications. We delve into its functionality, advantages, and suitability for your specific parts.

If you want to learn more about Hubs' 3D printing technology, visit our page on 3D printing services.

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HP Multi Jet Fusion printers

What is Multi Jet Fusion (MJF) 3D printing? #

MJF is a 3D printing process that quickly produces accurate and highly detailed complex parts with powdered thermoplastics.

Thanks to its ability to consistently and rapidly deliver parts with high tensile strength, fine feature resolution, and distinct mechanical properties, MJF 3D printing services have rapidly become the go-to additive manufacturing solution for industrial applications. It is often used to produce functional prototypes and end-use parts that require consistent isotropic mechanical properties and have intricate and complex geometries.

How was MJF developed? #

HP Additive introduced MJF to the market in 2016, leveraging the company's knowledge in inkjet printing technology and precision mechanics. The origins of MJF date back several decades, however.

In the 1990s, additive manufacturing (AM) started transitioning from solely being used for research and development to having practical, industrial applications in manufacturing. However, speed became a major obstacle during this transition. Compared to injection molding or metal stamping, many 3D printers took a long time to produce parts.

Early adopters of 3D printing technology took the approach of using "farms" or arrays of multiple machines to speed up production by printing higher quantities with extra machining power. HP, on the other hand, opted for a more integrated approach focused on automation.

At their worldwide AM center in Barcelona, HP designed a system that manufactures parts by building layers in a large powder material bed, with additional machinery for effortless post-processing. This system, akin to Selective Laser Sintering (SLS) and other powder bed fusion designs, has now advanced into the current MJF technology.

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Multi-jet fusion print bed

How does Multi Jet Fusion (MJF) work? #

MJF utilizes an inkjet array to deposit fusing and detailing agents into a bed of powder material, which are then fused into a solid layer. The printer subsequently lays down more powder on top of the bed, and this process is repeated layer by layer.

Here is a step-by-step breakdown of how MJF fabricates parts:

  • First, the moveable build unit is placed into the
  • printer, and then the material recoater carriage moves across the build area, depositing a thin layer of powder material.
  • The print and fuse carriage travels over the build area, heating the powder to a specific temperature for material consistency.
  • Inkjet nozzles fuse agents onto the powder bed in sections that match the geometry and characteristics of the part.
  • After each layer is completed, the build unit retreats to allow space for the next material layer to be deposited.
  • This process is repeated until the build is finished.

When the print job is complete, the build unit will contain the printed component along with unfused powder. To cool and unpack the part and reclaim any extra powder, you'll use a separate processing station that is connected to the movable build unit. The next step would be bead blasting to eliminate any residual powder before starting with additional cosmetic steps.

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Top view of MJF printer
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Unfused powder and the fused part
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Applying fusing and detailing agent

What materials does MJF use? #

Generally, the materials used for MJF can be divided into rigid and flexible plastics. Rigid plastics comprise Nylon PA11, Nylon PA12, and PP, while flexible plastics include Estane 3D TPU M95A. The HP system primarily concentrates on polyamide materials, which were developed by HP and its partners.

We have provided a list of the available MJF 3D printing materials on the Hubs platform.

Material Description
HP PA 12 (Nylon 12) Nylon 12 is a robust thermoplastic with all-around excellent physical properties and chemical resistance, ideal for functional prototypes and end-use applications.
Glass-filled HP PA 12 Glass-filled nylon is reinforced with glass bead and creates parts with higher stiffness and thermal stability than standard nylon.

How does MJF post-processing work? #

To prepare a part for prototyping or end-use applications, further processing is necessary, as with other manufacturing processes. However, MJF post-processing is relatively light compared to other AM technologies.

After finishing a print job, a build unit filled with a three-dimensional bed of unfused powder, with the part buried inside, is left.

These are the primary steps in MJF post-processing:

  • Cooling. This process occurs in the build unit, although HP provides module units for natural cooling, allowing for a new print to occur without waiting for the powder and part to cool.
  • To reclaim unfused powder, after the build unit cools down, transfer it to the processing station and vacuum the unfused powder into a container for future use.
  • Bead blasting is then used to eliminate any remaining powder using methods such as bead blasting, air blasting, or water blasting. You can perform this task manually or with the use of a tumbler, ultrasonic cleaner, or vibratory finishing machine.

Once all residual powder material has been removed, additional post-processing may be necessary depending on the part. For example, casting processes may call for further machining on mating surfaces, bores, tolerances surpassing MJF's capabilities, and internal threads. Moreover, adhering to specific technical requirements may necessitate manually sanding the part.

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Vacuuming of the unfused powder

What are the advantages of MJF? #

MJF (Multi Jet Fusion) is a 3D printing technology that offers several advantages, making it a popular choice for various applications. Here are some key advantages of MJF:

  1. Speed: MJF is known for its fast printing speed. It utilizes an array of print heads to jet a fusing agent onto a powdered material bed and then selectively applies an energy source (typically a thermal source) to fuse the material. The ability to simultaneously jet multiple agents allows for rapid and efficient production of parts, significantly reducing printing time compared to other 3D printing technologies.
  2. High Resolution and Detail: MJF can achieve excellent detail and high-resolution prints. The print heads deposit the fusing agent precisely, resulting in fine features, intricate geometries, and sharp edges. This makes MJF suitable for applications where accuracy and fine details are crucial.
  3. Material Versatility: MJF supports a wide range of materials, including various thermoplastics, such as PA12 (Nylon), PA11, TPU, and more. These materials offer different properties, including strength, flexibility, and temperature resistance, allowing for diverse applications in industries such as automotive, aerospace, and consumer goods.
  4. Functional Parts: MJF produces parts with good mechanical properties, including strength and durability. The fusion of the powdered material results in solid and dense parts that can withstand demanding functional applications. This makes MJF suitable for producing end-use parts, functional prototypes, and jigs and fixtures.
  5. Volumetric Scalability: MJF allows for the simultaneous printing of multiple parts within the build chamber, irrespective of their size or complexity. This enables efficient batch production, reducing production time and increasing productivity. Additionally, MJF can consolidate multiple components into a single print, reducing assembly requirements and improving overall part performance.
  6. Cost-Effectiveness: MJF can be a cost-effective option for producing medium to large quantities of parts. The high printing speed and the ability to produce multiple parts in a single print job help reduce per-unit costs. Additionally, MJF eliminates the need for tooling, reducing upfront expenses and making it economical for prototyping and low to medium-volume production.
  7. Post-Processing Flexibility: MJF parts require minimal post-processing compared to some other 3D printing technologies. The excess powder can be easily removed, and the parts may require minimal finishing, such as sanding or dyeing, to achieve the desired surface finish. This reduces post-processing time and labor costs.

MJF offers a combination of speed, resolution, material versatility, and cost-effectiveness, making it a compelling choice for various industries and applications. Its ability to produce functional parts with high accuracy and efficiency sets it apart as a competitive 3D printing technology.

Why is MJF ideal for manufacturing end-use parts? #

MJF (Multi Jet Fusion) is considered ideal for manufacturing end-use parts due to several key factors:

  1. Strength and Durability: MJF produces parts with excellent mechanical properties, including strength and durability. The fusion of the powdered material during the printing process results in solid and dense parts that can withstand demanding functional applications. This makes MJF suitable for manufacturing end-use parts that require high-performance characteristics.
  2. Material Versatility: MJF supports a wide range of materials, including various thermoplastics like PA12 (Nylon), PA11, TPU, and more. These materials offer different properties, such as strength, flexibility, and temperature resistance. The ability to choose from a variety of materials allows manufacturers to select the most suitable material for their specific end-use part requirements.
  3. Design Freedom: MJF provides design freedom, enabling the creation of complex geometries and intricate details that may be difficult or impossible to achieve with traditional manufacturing methods. The precise deposition of the fusing agent by the print heads allows for fine features and sharp edges. This design flexibility enables the production of customized end-use parts tailored to specific applications.
  4. Speed and Scalability: MJF is known for its fast printing speed. The simultaneous printing of multiple parts within the build chamber, regardless of their size or complexity, allows for efficient batch production. This scalability and printing speed make MJF suitable for manufacturing end-use parts in medium to large quantities, reducing production time and increasing productivity.
  5. Cost-Effectiveness: MJF can offer cost advantages for manufacturing end-use parts. The ability to produce multiple parts in a single print job helps reduce per-unit costs. Additionally, MJF eliminates the need for tooling, which can be expensive and time-consuming in traditional manufacturing processes. This reduces upfront expenses and makes MJF economically viable for low to medium-volume production.
  6. Post-Processing Efficiency: MJF parts require minimal post-processing compared to some other 3D printing technologies. The excess powder can be easily removed, and the parts may require minimal finishing, such as sanding or dyeing, to achieve the desired surface finish. This reduces post-processing time and labor costs, contributing to overall manufacturing efficiency.

By offering strength, material versatility, design freedom, scalability, cost-effectiveness, and post-processing efficiency, MJF is well-suited for the production of end-use parts. It provides manufacturers with a reliable and efficient manufacturing solution that meets the requirements of various industries, including automotive, aerospace, consumer goods, and more.

MJF vs SLS 3D printing: what’s the difference? #

MJF (Multi Jet Fusion) and SLS (Selective Laser Sintering) are two popular 3D printing technologies that share some similarities but also have distinct differences. Here are the key differences between MJF and SLS:

  1. Printing Process: In MJF, a thermal energy source is used to selectively fuse powdered material together, layer by layer. It involves jetting a fusing agent onto the powdered material bed, followed by an energy source to fuse the material. SLS, on the other hand, uses a high-power laser to selectively fuse powdered material particles together. The laser scans the powdered material bed, fusing the particles to form the desired shape.
  2. Printing Speed: MJF is generally faster than SLS. MJF employs an array of print heads to simultaneously jet the fusing agent, allowing for rapid and efficient production of parts. SLS, on the other hand, relies on a laser to scan and fuse the material, which can be a slower process.
  3. Surface Finish: MJF typically produces parts with smoother surface finishes compared to SLS. The fusing agent used in MJF helps to create a more uniform surface texture. SLS parts may have a slightly rougher surface due to the laser sintering process.
  4. Detail and Resolution: MJF can achieve higher levels of detail and resolution compared to SLS. The precise deposition of the fusing agent in MJF allows for finer features and sharper edges. SLS, while capable of creating detailed parts, may have limitations in achieving intricate geometries and fine details.
  5. Material Selection: Both MJF and SLS offer a wide range of materials. However, the specific materials available may vary between the two technologies. SLS is known for its extensive material compatibility, including various thermoplastics, metals, and ceramics. MJF primarily focuses on thermoplastics, such as PA12 (Nylon), PA11, and TPU. Material availability and options may depend on the specific machine and manufacturer.
  6. Part Consolidation: MJF has an advantage in part consolidation, where multiple components can be combined into a single printed part. The ability to print multiple parts simultaneously and fuse them together during the printing process makes MJF suitable for creating complex, consolidated parts. SLS can also achieve part consolidation, but it may require additional post-processing steps or support structures.
  7. Cost: The cost of MJF and SLS can vary depending on factors such as material, machine capabilities, and part complexity. MJF is generally considered more cost-effective for medium to large quantities of parts due to its faster printing speed and ability to produce multiple parts in a single print job. SLS can be cost-effective for smaller batch sizes or when using specific materials not available in MJF.

Both MJF and SLS offer unique advantages and are suitable for various applications. Choosing between them depends on factors such as desired part quality, speed, material options, surface finish requirements, and budget considerations.

MJF vs. Injection Molding: which is better for your application?  #

Deciding between MJF (Multi Jet Fusion) and injection molding for your application depends on several factors. Here are some considerations to help you determine which option may be better suited for your specific needs:

  1. Production Volume: Injection molding is typically more cost-effective for high-volume production runs. The initial setup costs for injection molding can be significant, but the per-unit cost decreases as the volume increases. On the other hand, MJF is well-suited for low to medium-volume production or prototyping, as it offers faster turnaround times and lower upfront costs compared to injection molding.
  2. Complexity and Design Freedom: If your application involves complex geometries, intricate details, or the need for design flexibility, MJF may be a better choice. MJF enables the creation of complex and customized parts with high accuracy and resolution, allowing for design iterations and customization without the need for costly tooling. Injection molding is better suited for simpler geometries with consistent wall thicknesses and may have limitations in achieving intricate designs.
  3. Material Selection: Injection molding offers a wide range of material options, including various thermoplastics, elastomers, and engineered resins. The material properties can be fine-tuned to meet specific application requirements. MJF also provides material versatility, but the range of available materials may be more limited compared to injection molding. Consider the required material properties, such as strength, heat resistance, and chemical resistance, to determine which technology can fulfill your application needs.
  4. Time Constraints: If you have time constraints and require faster turnaround times, MJF is advantageous. MJF has shorter lead times due to its additive manufacturing process, allowing for rapid prototyping and production. Injection molding, on the other hand, requires the fabrication of molds, which can take weeks or months, depending on the complexity. Once the molds are ready, the production process is generally faster, but the initial setup time should be considered.
  5. Cost Considerations: Cost is a significant factor in the decision-making process. Injection molding requires the upfront investment in molds, which can be expensive, particularly for complex designs. MJF eliminates the need for molds, reducing upfront costs. For low to medium-volume production runs, MJF can be a cost-effective solution. However, for very high-volume production, injection molding can offer lower per-unit costs due to economies of scale.
  6. Iterative Design and Prototyping: If you need to iterate designs, test prototypes, or make frequent design changes, MJF is advantageous. MJF allows for rapid prototyping and quick design iterations without incurring the costs associated with modifying molds. Injection molding, while capable of producing high-quality prototypes, may involve additional costs and time for mold modifications.

Ultimately, the choice between MJF and injection molding depends on your specific application requirements, production volume, time constraints, design complexity, and cost considerations. It may be beneficial to consult with experts or service providers in both technologies to assess which option aligns better with your project's needs.

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3D printed part in dyed black + vapor smoothed surface finishing

What are examples of Multi Jet Fusion in action? #

Multi Jet Fusion (MJF) has been applied across various industries and has found utility in numerous applications. Here are some examples of MJF in action:

  1. Automotive Industry: MJF is utilized in automotive manufacturing for producing functional end-use parts, prototypes, and tooling. Examples include interior components like air vents, brackets, and dashboard trim, as well as exterior parts like grilles and mirror housings. MJF's ability to create complex geometries and consolidate multiple components into a single print makes it suitable for automotive applications.
  2. Aerospace Industry: MJF finds applications in the aerospace sector for producing lightweight and durable components. It is used for manufacturing parts like air ducts, brackets, housings, and prototypes for testing. MJF's capability to produce parts with high strength-to-weight ratio and its design flexibility are particularly valuable in aerospace applications.
  3. Consumer Goods: MJF is employed in the production of various consumer goods. It can create customized and personalized items such as phone cases, eyewear frames, jewelry, and fashion accessories. MJF's ability to achieve fine details and its material versatility allow for the production of aesthetically appealing and functional consumer products.
  4. Medical and Healthcare: MJF has found applications in the medical field for producing custom prosthetics, orthotics, and anatomical models. It enables the creation of patient-specific devices with intricate designs and precise fit. MJF's speed and accuracy make it suitable for producing prototypes and end-use parts used in medical research and development.
  5. Industrial Manufacturing: MJF is used in industrial manufacturing for producing functional components and tooling. It is employed in the creation of jigs, fixtures, and manufacturing aids that streamline production processes. MJF's ability to produce complex shapes and consolidate multiple parts improves efficiency and reduces assembly requirements in industrial settings.
  6. Architecture and Design: MJF is utilized by architects and designers for creating architectural models, prototypes, and intricate designs. It enables the production of detailed and visually appealing models that assist in design visualization and client presentations. MJF's ability to produce high-resolution and complex geometries supports the realization of architectural concepts.

These are just a few examples of how MJF is applied across various industries. The versatility, speed, design flexibility, and material options offered by MJF make it a valuable technology for a wide range of applications, from functional prototyping to end-use part production.

MJF: Handy tips and tricks #

Certainly! Here are some handy tips and tricks for working with Multi Jet Fusion (MJF):

  1. Orientation Matters: Proper part orientation can significantly impact the quality and strength of MJF parts. Consider the geometry and features of your design when deciding on the orientation. Orientation affects factors like surface finish, dimensional accuracy, and build time. Experiment with different orientations to find the optimal balance for your specific part.
  2. Wall Thickness: Design your parts with appropriate wall thickness to ensure structural integrity. MJF performs best with uniform wall thicknesses. Avoid extreme variations in wall thickness, as it can lead to warping or inconsistent part quality. Consult the MJF design guidelines provided by the manufacturer to determine the recommended minimum and maximum wall thicknesses for your chosen material.
  3. Support Structures: MJF typically requires support structures for overhangs and complex geometries. These structures provide stability during the printing process. Keep in mind that support removal can be time-consuming and may leave marks on the part's surface. Optimize your design to minimize the need for excessive support structures, balancing the part's functionality and support requirements.
  4. Surface Finishing: While MJF produces parts with good surface finish, you can further enhance the appearance by applying post-processing techniques. Sanding, polishing, or dyeing the parts can help achieve a smoother or more aesthetically pleasing surface finish. Experiment with different post-processing methods to achieve the desired look and feel for your parts.
  5. Part Consolidation: Take advantage of MJF's capability for part consolidation. When designing complex assemblies, consider combining multiple components into a single printed part. This can reduce assembly time, improve part strength, and optimize the overall design.
  6. Material Selection: Understand the material properties and characteristics of the available MJF materials. Different materials offer varying levels of strength, flexibility, heat resistance, and chemical resistance. Choose the material that best suits the requirements of your application. Consult the material data sheets and technical specifications provided by the manufacturer to make informed decisions.
  7. Iterative Design: MJF is well-suited for iterative design and prototyping due to its fast turnaround time. Leverage this advantage by testing and refining your designs through multiple iterations. Use the feedback from each iteration to improve the final design and ensure optimal functionality and performance.
  8. Collaborate with Experts: If you're new to MJF or have complex requirements, consider collaborating with experts or service providers who have experience with the technology. They can provide guidance on design optimization, material selection, and post-processing techniques, helping you achieve the best possible results.

By keeping these tips and tricks in mind, you can maximize the benefits of MJF and optimize your design and production processes. Remember to refer to the specific guidelines and recommendations provided by the MJF machine manufacturer and material supplier for the most accurate and up-to-date information.

Frequently asked questions #

What are the advantages of MJF? #

MJF enables the production of numerous distinct parts without the need for arrays of multiple printers. Additionally, it can eliminate expensive casting or molding processes, and current HP systems include a bulk post-processing station to reduce manual finishing steps.

What are the disadvantages of MJF? #

MJF incurs higher costs compared to modular printing technologies like FDM, despite offering better quality and consistency for industrial applications.

Are 3D printed parts made with MJF technology water resistant? #

PA 12 Nylon is one of the few 3D printing materials that exhibit water resistance. MJF parts can be made water-resistant by ensuring the thickness of the walls is at least 1 mm. Any walls over 4 mm thick can seal parts, making them watertight. Moreover, MJF parts offer chemical resistance against alkalies, greases, oils, and aliphatic hydrocarbons.

What is the dimensional accuracy of MJF? #

MJF's dimensional accuracy is ± 0.3%, with a lower limit of ± 0.3 mm (0.012 inches).

What is the biggest size MJF can build? #

With V1, the biggest size for building MJF parts is 380 x 285 x 380 mm (14.9 x 11.2 x 14.9 inches).

MJF can print features as small as 0.5 mm (0.02 in). #

What is the minimum feature size that MJF is capable of printing? MJF can print features as small as 0.5 mm (0.02 in). MJF can print features as small as 0.5 mm (0.02 in). The print layers in MJF are 80 microns (0.0003 in) thick, enabling it to produce intricate surface details.

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