What Is SLS 3D Printing? Selective Laser Sintering Guide.

by Mike Brooks | Last Updated: May 3, 2022

Selective Laser Sintering (SLS) is one of the Additive Manufacturing technologies in 3D printing.

What Is SLS 3D Printing?

SLS technology uses a high-power laser to sinter small polymer powder particles into a solid structure 3D model.

Due to machinery, material, and software advancements, the selective laser sintering process enjoys wide acceptance in the 3D printing industry.

Many businesses now use these additive manufacturing processes compared to a few years ago when just a few high-tech industries could afford it.

More significantly, Selective Laser Sintering (SLS) is popular among 3D printing hobbyists and professionals because it offers low cost per part, high productivity, and the use of established material.

What Is the Difference Between SLS and SLA?

Stereolithography (SLA) is the most common and popular resin 3D printing technology.

It is widely used in various applications because it offers you the ability to produce high-accuracy isotropic and watertight prototypes and end-use parts.

So what are the main differences between the SLS process and SLA?

There is a material difference in that SLA works with polymer and resin but not metal. Conversely, SLS works with special polymers like nylon and polystyrene, and at the same time, it handles metal such as steel and titanium, among others.

SLA works primarily with liquids, while SLS uses powder in its 3D printing process.

Both techniques use lasers but operate distinctly at different wavelengths to cure epoxy within the resin.

SLS uses a higher-powdered laser to sinter and compact metal powder. At the same time, SLA can be used at lower peak power.

SLS remains tougher and inexpensive. On the other hand, SLA offers parts with a more formidable dimensional tolerance.

What Is Injection Molding?

Injection molding is a manufacturing process that produces objects or parts by injecting molten material into a mold.

It uses numerous materials such as glasses, elastomers, metals, confections, and thermoplastics.

Is SLS or FDM Better?

SLS and FDM 3D printing are additive manufacturing processes prevalent in the 3D printing industry.

Each of these methods has pros and cons, and you need to identify their fundamental differences so that you can choose what suits your unique 3D printing needs.

Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF) is additive manufacturing technology.

The FDM 3D printer extrudes molten thermoplastic filaments like the ABS and PLA through the printer’s hot end. The heated nozzle applies the plastic layer by layer on the plastic parts until the process is completed.

On the other hand, Selective Laser Sintering (SLS) is an additive manufacturing process that lets lasers compact and sinter powdered particles into solid structures based on the 3D model.

SLS 3D printing technique has a wide range of industrial applications in aerospace, healthcare for medical devices, and electronics. Consequently, the SLS method calls for the use of large SLS 3D printers that are very costly.

For its part, FDM 3D printing technology remains the cheapest additive manufacturing layer technology. It remains the preferred choice of people who lack big budgets, as with large industrial companies.

Depending on the printer, SLS lead time proves shorter than the FDM lead time. Moreover, the printing speed for SLS reaches 48 mm/h. On the other hand, the FDM speed ranges between 50-150 mm/h.

Post-processing is another area where the difference between SLS and FDM manifests. SLS post-processing is simple. It would help clean up the unsintered powder that acted as the support structure during the 3D model build-up process.

You can post-process the SLS 3D print manually or use compressed air.

Contrastingly, post-processing methods in FDM are complicated. The improper dissolving of support structures can lead to 3D print model damage.

Also, you need to use specialized equipment like an ultrasonic bath or glass containers that add to the post-processing cost.

What Are the Advantages of SLS?

SLS 3D printing technology offers numerous advantages that make it popular for industrial applications and individual use:

• Provides high dimensional accuracy
• Comparative high-resolution levels
• Fast lead times
• High tensile strength and stiffness
• Produce robust 3D printed parts
• Economic printing cost

What Is the Difference Between SLS and SLM?

3D Selective Laser Sintering (3D SLS) works by atomically fusing bulk powdered industrial material using high-powered lasers.

On the other hand, Selective Laser Melting (SLM) combines powdered materials by heating them till they reach melting point.

Generally, the two are almost similar processes but differ significantly on the material they use. More importantly, Selective Laser Melting (SLM) behaves similarly to the SLS but can do more functions.

For example, SLM uses laser technology to beam and heat powdered material until it reaches melting point.

Thus, while SLS fuses the powdered material particles, SLM melts the same into a homogeneous part.

SLM creates more robust 3D models than the SLS in the long run. Furthermore, SLM leaves fewer or no voids; hence no or minimal part failures are witnessed.

What Is Selective Laser Sintering (SLS)?

Selective Laser Sintering (SLS) 3D printing is an additive manufacturing process associated with the powder bed fusion family. In SLS 3D printing process parameters, the SLS printer achieves rapid manufacturing by using laser technology.

The lasers selectively sinter and fuse small particles, creating a 3D model layer by layer.

SLS printing allows the prototyping of functional parts with good mechanical properties.

How Does SLS Work?

The Selective Laser Sintering Process

In the SLS 3D printing process, you apply a thin powdered material to a build platform and heat it. Use the laser to heat the powdered material below the melting temperature resistance.

Next, use your SLS 3D printer laser to trace the cross-section of the part geometry of the first layer. Also, the laser provides sufficient energy to melt the powdered material.

Additionally, the various composite material powders need a low viscosity and surface tension to merge and form a recognizable melt pool.

Surrounding composite material powders stay solid, keeping the shape of the molten geometry intact.

At this point, the lower build platform increase by one layer height. It will make room for the next layer. At the same time, a sweeper will move across the surface, picking up excess material from the reservoir.

It then deposits powdered particles on the build platform to create the next layer. You shall repeat the powder coating process and layer meting until you finish building the whole part.

How Strong Is SLS 3D Printing?

The mechanical properties of SLS 3D printed nylon parts make them strong, sturdy, stiff, and durable. It is the primary reason SLS 3D printing remains famous for building durable and impact-resistant final parts.

The Nylon 12 Powder remains a popular SLS 3D printing material that is known for its strong material tensile strength and durability;

• Tensile strength 50 MPa
• Tensile modulus 1850 MPa
• Elongation at break (X/Y) 11%
• Elongation at break (Z) 6%

How Is SLS Different From Normal 3D Printing?

Selective laser sintering (SLS) 3D printing technology is different from traditional 3D printing because it uses lasers to heat powdered nylon material to create 3D models.

Conversely, a normal 3D printing process utilizes the hot end to heat and extrude plastic filaments on a heated bed to build 3D models.

Also, SLS 3D printing produces higher resolution and dimensionally accurate printed parts than regular 3D printing. Nylon material properties make SLS parts come out with high tensile strength and stiffness.

More importantly, selective laser sintering doesn’t need support structures as the unsintered powder bed surrounds and holds the parts during print building.

The traditional manufacturing methods are known for the low volume production of plastic parts.

So normal 3D printing process significantly improved the production of multiple components and heralded an increase in production volumes.

However, the SLS machines saw the production of complex geometries. For example, SLS allows you to produce interlocking parts that can move. In short, an SLS machine enables you to print a highly complex desired three-dimensional shape.

How Fast Is SLS Printing?

SLS machines print additive materials with consistent mechanical properties such as the Nylon 12 powder to create 3D models. But how fast is the SLS printing machine?

The SLS printers enable the printing of complex geometric shapes. It prints at the speed of 20 mm/h and has a minimum layer thickness of 0.05 mm. The printer’s speed can reach a maximum of 48 mm/h

Does SLS Use a Laser?

Yes! The selective Laser Sintering process uses a laser to produce parts such as those used for functional prototyping. Equally, it doesn’t require support structures to build features.

SLS, an additive manufacturing layer technology, uses a high-power laser such as a carbon dioxide laser to fuse and sinter small particles of coated powders into a mass of desired three-dimensional shape.

Pros & Cons of SLS

SLS 3D printing is popular for printing complex geometries complete with detailed interior components and other mechanical joints that support the part movement.

However, it is essential to familiarize yourself with both the advantages and disadvantages of SLS 3D printing before you decide to use this technology.

Pros

• Enables easy batch printing
• It doesn’t require support structures for printing
• Produce detailed and complex prints
• Suitable for use in experiments
• It offers a high-speed 3D printing
• Produce robust printed replacement parts
• It provides a high dimensional accuracy

Cons

• Raw material variety is limited
• Challenging to shift from FDM/SLA to SLS 3D printing
• Recycling of material is not possible
• Potential health risks
• Brittle parts
• Difficult post-processing

Is SLS Printing Expensive?

Traditionally, SLS 3D printing has remained expensive and inaccessible to many businesses. Expensive SLS printers account for the high costs.

The SLS machines are costly because of the integration of high-powered and quality lasers; an SLS machine preheats powdered particles and the SLS machine’s complex configuration.

Consequently, the SLS printing system is costly as it requires the training of experts.

Market values of the industrial SLS 3D machines start at around $100,000, making them inaccessible to many.

Is SLS Stronger Than SLA?

SLS printing means selective Laser Sintering. It produces 3D printed parts that are stronger than the SLA (Stereolithography) technique that creates highly detailed prints with a smooth surface finish though brittle.

Depending on the resin resolution, SLA printed parts are strong though brittle. As such, SLS remains a more robust option that is highly flexible and durable.

SLS parts’ toughness and flexibility make it readily sought out for building mechanical parts. However, it doesn’t offer the advantage of a smooth surface finish. SLS materials produce 3D parts with a rough surface.

Conclusion

Selective Laser Sintering (SLS) is a popular 3D printing technology that uses a laser to sinter and compact powdered SLS materials. It is used in 3D rapid prototyping and other industrial applications that need durable, flexible, and printed solid parts.

SLS 3D printing uses powdered nylon instead of thermoplastic polyurethane commonly used in FDM 3D printing. SLS technology is an additive manufacturing technology, meaning you print the parts layer after layer until it is complete.

Michael Brooks is the founder of M3DZone.com. He sees a very bright future for 3D printing that's why his mission is to try and make this easy for everyone. Discover your hidden talent and creativity. You can follow here: Facebook, Twitter & Pinterest.