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3D Printing Methods: Differences between FDM, SLA, SLS

There are many 3D printing technologies, but they all have a common purpose: to create 3D parts or models. All these technologies create parts through layers, but each one of them has a different process and choosing between them can be tricky.

In this article we’ll explain in depth the three most used plastic 3D printing processes we currently offer at M Aerospace: Fused Deposition Modeling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS)


FDM technology is the most common in the world of 3D printing. It’s the most commonly used by amateurs who delve into this type of printing. It is one of the most frequently purchased printers since, in general, it has a fairly affordable price and is very easy to use.

The technique that FDM performs is suitable for simple parts, as well as prototypes and parts that could be machined. Compared to SLA and SLS technologies, the precision in FDM is very low, and therefore it is not the most suitable for printing designs with complex features. The surface finish of the parts is of poor quality and to obtain better results it is necessary to carry out some chemical or mechanical polishing.


Stereolithography was the first 3D printing technology invented in 1983. Over the years, developments in stereolithography made it accessible at the user level, resulting in much faster printing.

Stereolithography provides great precision and high resolution in its impressions, with very smooth surfaces and great detail, which is why they are regularly used in jewelry and cosmetic dentistry for the creation of molds. Materials for SLA have overdeveloped, creating resins with a wide range of optical, mechanical and thermal properties.

One drawback with this technology is that after being printed, the part must be immersed in a special solvent and, sometimes, in a UV oven to finish the curing process.

SLA is indicated for highly detailed prototypes that require tolerances and smooth surfaces, such as molds, patterns and functional parts. SLA offers a wide variety of functional applications.


Selective laser sintering is the most commonly used method for industrial applications, since it has the ability to print resistant and functional parts.

In this process, the use of support (like polishing) is not necessary as in SLA and FDM, since what it does is create the layer first and then sinter it. This makes the pieces very precise and their finishes very fine. SLS is suitable for models with complex geometries, undercuts, interior features, and thin walls.

The material used in SLS is nylon. Nylon has excellent mechanical properties, it’s light, strong and flexible.

Each of these technologies have their advantages and disadvantages and are suitable for different applications. The following table compares some of the key aspects within this industry.

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