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Although HP Multi Jet Fusion (MJF) and Selective Laser Sintering (SLS) are both types of Powder Bed Fusion (PBF) 3D printing technology, there are significant differences between the two. You will need to take these into consideration when you’re choosing which is right for you.
Evaluating MJF vs SLS will typically include factors such as your budget, mechanical properties, and specs for your application and how your 3D printed part needs to be finished.
Your ultimate choice of technology will be determined by the nature of your industry and the type of 3D printed part you want to produce.
It will also be important to have an idea of how many 3D printed parts you anticipate producing and how quickly you need to produce them.
Your decision will also be influenced by where you’re at with design and production. So, if your priority is developing a design, you’ll be more interested in printing cheaply and quickly and not worrying so much about the finish and scaling a full manufacturing process.
When you’ve perfected your design, you’ll be able to focus more on the look and feel and producing in larger quantities.
Once you know what you’re looking for, as best you can, you can decide on the process that most suits you.
This article offers an overview of the benefits of SLS vs MJF to help you begin the process of deciding which is best for you.
PBF technologies—a comparison
SLS and HP MJF belong to the PBF family of technologies. PBF technologies use heat or light energy, typically in the form of a laser or electron beam, to melt or fuse powder material spread over each previous layer.
This is done in different ways, including using a blade or roller. Fresh material is delivered from a hopper or reservoir below the print bed or from a top feeding system.
Apart from SLS and HP MJF, there are other PBF 3D printing technologies:
- Direct Metal Laser Sintering (DMLS). This uses the same principle as SLS but with metals and not plastics. It requires support structures usually made using the same material as the part being 3D printed, the cost of which needs to be factored into your total material cost.
- Electron Beam Melting (EBM). A reasonably recent and advanced technique to produce metal parts, primarily used in structural and medical applications, for example. Material is melted in a vacuum at high temperatures. This method also requires support structures.
- Selective Heat Sintering (SHS). SHS uses a thermal printhead to heat layers of powdered thermoplastic sintered to form the next cross-section. As with MJF and SLS, there’s no need for support structures.
Sintering is the process of using heat or pressure to compact and form a solid mass of material without it melting.
What is SLS?
SLS uses a laser as the power source to selectively melt plastic powder into a single 3D object. After each section is fused, the powder bed is lowered by one layer’s thickness, and a new layer is applied on top. The process is repeated until the object is completed.
You can use powder-based thermoplastic polymers, including nylons. PA12 is the most commonly used, but you can also work with PA11, or carbon-fiber and glass-filled or aluminum-filled nylons.
What is HP Multi Jet Fusion?
HP MJF is best described as a combination of PBF and Binder Jetting technologies.
Unlike SLS or Fused Deposition Modeling (FDM), which uses a point-by-point printing approach like a pen plotter, HP MJF technology creates one area-wide layer of many parts layer by layer. It does so leveraging proprietary HP PageWide printing technology.
With HP MJF, a layer of powder material is spread on the print bed. Next, the fusing and detailing agents are deposited at voxel-level on top of the powder, defining the regions of the layer that need to be fused or protected from fusion, respectively. A voxel is the 3D printing equivalent of a pixel.
Heat is applied to the bed and the areas where the fusing agent was deposited are fused. Once these fused layers cool down, they solidify and build the designed 3D printed part.
SLS vs MJF — key factors
SLS was among the first 3D printing technologies to be invented back in the 1980s. On the other hand, MJF first made waves in the 3D printing industry in 2016, when HP expanded from 2D to 3D printing, launching an MJF-powered industrial 3D printer.
Today, HP MJF technology is set to reinvent the way we design and manufacture and overcome the limitations of existing 3D printing technologies. The goal is to drive widespread adoption of 3D printing in manufacturing beyond prototyping and deliver new levels of productivity, speed, part quality, and cost.
MJF and SLS both produce strong, functional 3D printed parts. Thanks to its detailing agent, which modifies fusing and creates fine detail and smooth surfaces, MJF can achieve fine detail resolution while maintaining mechanical properties for functional, quality parts. This enables small holes, lattices, and textures to be printed accurately.
MJF also delivers isotropy and mechanical properties combined with productivity – throughput and cost per part. Predictable print times allow you to plan production accurately, which is critical for manufacturing environments.
Although SLS has a large build volume that enables it to deliver a variety of part sizes, print time may vary depending on the application.
Materials are an important factor in your overall cost per part, and the reusability of materials can make for significant savings.
HP 3D High Reusability materials, compatible with MJF industrial 3D printing systems, deliver consistent performance with up to 100% surplus powder reuse1, which impacts the total cost of ownership and running costs.
HP MJF also enables you to print a functional prototype that behaves like a final product, allowing you to move seamlessly from design to production stage.
Case study: HP MJF helps Bowman International disrupt the bearing industry
Bearing cages can be one of the most significant factors in bearing performance. They're also the most complex part of a bearing.
Bowman International is a leading manufacturer and supplier of plain bearings in the United Kingdom and throughout Europe.
Its standard range of bearing cages would have traditionally been produced using steel, bronze, or aluminum. These materials can create noise and vibration during operation, compromising the material’s durability and part quality.
Data courtesy2
Extremely complex geometries made it impossible for Bowman to use traditional processes, like injection molding to produce the thousands of bearing cages they needed to manufacture per month.
Initially, Bowman used SLS to 3D print tooling and part. But they found that for their application, this technology increased the likelihood of warping and inconsistent mechanical properties in the final part and was therefore not suitable for them to produce reliable 3D printed tooling or 3D printed parts.
Faced with this challenge, Bowman sought new ways to design and manufacture their parts. They subsequently opted for HP Multi Jet Fusion (MJF) technology to take prototyping into production and then on to volume production, particularly for bearing cages and seals.
Learn how, with HP MJF, Bowman engineers invented a new design for 3D printed bearing cages and seals, disrupting the bearings industry with high-performance parts.
To learn more about MJF vs other 3D printing processes – for example, MJF vs FDM or MJF vs SLA – read our "3D printing and additive manufacturing processes" article.
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Footnotes and disclaimers
- Based on internal HP testing, May 2020. HP Jet Fusion 3D Printing Solutions using HP 3D High Reusability PP enabled by BASF provide up to 100% powder reusability ratio, producing functional parts batch after batch. For testing, material is aged in real printing conditions and reclaimed powder is tracked by generations (worst case for reusability). Parts are then made from each subsequent generation and tested for mechanical properties and accuracy showing no degradation of properties up to three generations of use.
- Data courtesy of Bowman.