SLS vs. SLA: Key Differences & Practical Comparison

Another advantage SLS offers is that you don’t need any support structures during printing—the surrounding powder can actually provide support for any overhanging parts. A lot of our customers use it for their time-sensitive projects as it’s very quick. If you’re interested in buying one of these printers for your business, prepare to make a substantial investment. SLS machines are not only expensive to buy, but they also use up a lot of electricity, racking up those utility bills. You’ll also want to make sure you’ve got enough space in your office or lab for them as they’re on the bulky side. 

What are the Advantages of SLS Compared to SLA?

There are advantages to using SLS vs. SLA. Some are listed below: 

1. SLS parts need no support structures during production while SLA parts do. The surrounding powder serves to support overhanging components during the building process. SLA parts need to be designed with supporting structures or built in such a way that makes the parts self-supporting.
2. The SLS production process is faster than SLA. That makes it handy for rapid prototyping activities.
3. The parts produced via SLS are tougher than those of SLA, so they’re more often used as functional parts.

What are the Disadvantages of SLS Compared to SLA?

Though SLS is very capable, it still has its disadvantages. These include:

1. SLS machines are more expensive than SLA machines.
2. The SLS laser demands a lot of electricity. This means the print needs to be completely enclosed and shielded. The laser beam in SLA uses less power; users can view the print while it is enclosed behind plastic or tinted glass. 
3. SLS machines are bulkier. They typically fill an entire laboratory workbench. In contrast, SLA machines are often designed as desktop devices.

SLA Definition and Comparison to SLS

SLA, an abbreviation for stereolithography, is also a form of 3D printing that’s considered the oldest around. Invented in 1986 by 3D Systems’ founder Chuck Hall, SLA builds parts in a more peculiar way… upside down. It uses a type of laser, but this time it’s an ultraviolet laser that cures photosensitive resin into whichever shape you’ve chosen. While it prints, the build plate is always in contact with the resin tank. The laser points at specific parts until they’ve solidified, and then the plate raises out of the reservoir so the next layer can be cured. As this happens, each layer fuses with the one prior, and the whole process almost looks like the part is rising out of the liquid. You can see how these printers work in the following image:

Attribute

Sensitivity to UV light

SLS

No

SLA

Yes

Attribute

It makes rough surface finishes

SLS

Yes

SLA

No

Attribute

It’s limited regarding material compatibility

SLS

Yes

SLA

No

Attribute

The process is quick

SLS

Yes

SLA

No

SLS vs. SLA Comparison

The polymer resin used in SLA is sensitive to UV light. As such, it should be kept away from sunlight or any other source of light that contains UV radiation. SLS products do not have this shortcoming, and nor do they need supporting structures during manufacturing. The unfused powder particles are sufficient to provide support.

SLS vs. SLA: Technology Comparison

The high-powered laser in SLS is completely enclosed, giving operators no view of the print. SLA laser output is significantly lower in power and requires only tinted glass or a plastic enclosure to prevent the UV light from escaping.

SLS vs. SLA: Material Comparison

The polymer powder in SLS is easy to handle but users must wear gloves while handling SLA parts. The resin used in the production process is slightly harmful. Some commercially available production materials used in SLS include: polyaryletherketones, thermoplastic elastomers, polystyrenes, and nylon. SLA materials include but are not limited to: epoxy photopolymer, acrylic photopolymer, and some others with polypropylene-like and ABS-like properties.

SLS vs. SLA: Product Applications Comparison

SLS produces parts that are tougher than those of SLA. This makes them better options for mechanical or end-use applications.

SLS vs. SLA: Print Volume Comparison

Thanks to its size and the sintering time, SLS prints faster than SLA both on large- and small-scale models. In addition to this, SLS requires no supporting structures during the building process.

SLS vs. SLA: Cost Comparison

SLS devices are generally more expensive than SLA devices. In both cases, the cost is compounded over time since materials such as resin or powder have to be purchased regularly. SLS machines can be purchased for as little as $10,000 or as much as $650,000. The cost depends on the maximum build volume, minimum layer thickness, print speed, laser type, and the build materials it can accept. SLA machines, on the other hand, usually fall in the range of $3,750 to $5,000, depending on the size. They can be classified into four different types: DIY, advanced hobbyist, professional and performance, and business and industrial.

What are the Mutual Alternatives to the SLS and SLA?

Of course. The mutual alternative to both would probably be MJF—or multi-jet fusion. It can be used to make functional prototypes, proofs of concept, and end-use parts and doesn’t need a high-powered laser to do so. 

What are the Similarities Between SLS and SLA?

SLS and SLA share some basic similarities:

1. Both technologies employ lasers to fuse material. 
2. Both require post-processing. SLS parts have to be cleaned to remove excess powder and may need extra work to match surface-quality specifications. Similarly, SLA parts have to be cleaned to get rid of uncured resin.

What are the Other Comparisons for SLS Besides SLA?

Listed below are the 3D printing technologies that can also be compared to SLS:

Here are some specific SLS alternatives:

1. SLM (selective laser melting) uses metallic powder rather than polymer. To learn more, see our full guide on SLS vs. SLM.
2. EMB (electron beam melting) melts and prints metal parts under a vacuum with an electron beam.
3. FDM (fused deposition modeling) uses a heated nozzle to melt and create layers of filament material.

What are the Other Comparisons for SLA Besides SLS? 

Listed below are the 3D printing technologies that can also be compared to SLA:

1. MJ (material jetting) machines use an inkjet-like print head that sprays liquid photopolymer in the pattern of the cross-section of the part. After the spraying, a UV light is used to cure the polymer.
2. DLP (digital light processing) printers expose only parts of photopolymer resin to UV light to cure them. Unlike SLA, though, DLP printers use a projector light and thousands of tiny mirrors to direct it to or away from the print bed. To learn more, see our full guide on SLA vs. DLP.

Frequently Asked Questions About SLS and SLA

What other compatible materials are there for SLS and SLA printers?

There are a few different materials that can be used with these machines. When it comes to SLS printing, it’s quite normal to use materials like thermoplastic elastomers, polyaryletherketones, polystyrenes, and nylon. For SLA, you’d normally use something like epoxy photopolymer, acrylic photopolymer, and other materials with polypropylene- or ABS-like properties.

How much do SLS and SLA printers cost?

Obviously, the cost involves more than just purchasing the machine and your first batch of material. Costs will accrue depending on use. But as a general rule, SLS machines can be found for as low as $10,000 and can be as expensive as $650,000, depending on the type of machine and what you want it to do. SLA machine prices are a lot easier on the eyes—and wallet—with costs varying between $3,750 and $5,000, depending on size. Usually, when purchasing a machine like this, it might help you to understand which category it falls under: DIY, advanced hobbyist, professional and performance, or business and industrial.

Kat de Naoum

Kat de Naoum is a writer, author, editor, and content specialist from the UK with 20+ years of writing experience. Kat has experience writing for a variety of manufacturing and technical organizations and loves the world of engineering. Alongside writing, Kat was a paralegal for almost 10 years, seven of which were in ship finance. She has written for many publications, both print and online. Kat has a BA in English literature and philosophy, and an MA in creative writing from Kingston University.

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