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Selecting The Right 3D Printing Technology: FDM vs. SLA vs. SLS

Choosing the right 3D printer

It is widely accepted that 3D printing or additive manufacturing reduces costs, saves time, and transcends the limits of fabrication processes for product development. From concept models and working prototypes for product development to jigs, fixtures, or even end use parts in manufacturing, 3D printing technologies offer versatile solutions in a wide variety of applications.

High-resolution 3D printers are now very affordable, easier to use, and more reliable. 3D printing technologies are now accessible to more businesses, but selecting the best 3D printing solution for your needs can be confusing.

This article will compare the three most established technologies for 3D printing plastics today: fused deposition modeling (FDM), stereolithography (SLA), and selective laser sintering (SLS).

Formlabs SLA 3D printer

Fused Deposition Modeling (FDM)

Fused Deposition Modeling is the most widely used form of 3D printing at the consumer level, fueled by the emergence of hobbyist 3D printers. FDM 3D printers build parts by melting and extruding thermoplastic filament, which a print nozzle deposits layer by layer in a build area.

FDM works with a range of standard thermoplastics, such as ABS, PLA, and their various blends. The technique is well-suited for basic proof-of-concept models, as well as quick and low-cost prototyping of simple parts, such as parts that might typically be machined.

Selecting the right 3D printer

FDM parts tend to have visible layer lines and might show inaccuracies around complex features. This example was printed on a Stratasys uPrint industrial FDM 3D printer with soluble supports.

FDM has the lowest resolution and accuracy when compared to SLA or SLS and is not the best option for printing complex designs or parts with intricate features. Higher-quality finishes may be obtained through chemical and mechanical polishing processes. Industrial FDM 3D printers use soluble supports to mitigate some of these issues and offer a wider range of engineering thermoplastics, but they also come at a steep price.

 

Stereolithography (SLA)

Stereolithography was the world’s first 3D printing technology, invented in the 1980s, and is still one of the most popular technologies for professionals. SLA uses a laser to cure liquid resin into hardened plastic in a process called photopolymerization.

 

SLA parts have the highest resolution and accuracy, the clearest details, and the smoothest surface finish of all plastic 3D printing technologies, but the main benefit of SLA lies in its versatility. Material manufacturers have created innovative SLA resin formulations with a wide range of optical, mechanical, and thermal properties to match those of standard, engineering, and industrial thermoplastics.

Selecting the right 3D printer

SLA parts have sharp edges, a smooth surface finish, and minimal visible layer lines. This example part was printed on a [Formlabs Form 2 desktop SLA 3D printer


SLA is a great option for highly detailed prototypes requiring tight tolerances and smooth surfaces, such as molds, patterns, and functional parts. SLA is widely used in a range of industries from engineering and product design to manufacturing, dentistry, jewelry, model making, and education.

 

Selective Laser Sintering (SLS)

Selective laser sintering is the most common additive manufacturing technology for industrial applications.

SLS 3D printers use a high-powered laser to fuse small particles of polymer powder. The unfused powder supports the part during printing and eliminates the need for dedicated support structures. This makes SLS ideal for complex geometries, including interior features, undercuts, thin walls, and negative features. Parts produced with SLS printing have excellent mechanical characteristics, with strength resembling that of injection-molded parts.

Selecting the right 3D printer

SLS parts have a slightly rough surface finish, but almost no visible layer lines. This example part was printed on a Formlabs Fuse 1 benchtop SLS 3D printer

The most common material for selective laser sintering is nylon, a popular engineering thermoplastic with excellent mechanical properties. Nylon is lightweight, strong, and flexible, as well as stable against impact, chemicals, heat, UV light, water, and dirt.

The combination of low cost per part, high productivity, and established materials make SLS a popular choice among engineers for functional prototyping, and a cost-effective alternative to injection molding for limited-run or bridge manufacturing.

Compare FDM, SLA, and SLS Technologies

Each 3D printing technology has its own strengths, weaknesses, and requirements, and is suitable for different applications and businesses. The following table summarizes some key characteristics and considerations.

FDM V SLA V SLS

Costs and Return on Investment

Ultimately, you should choose the technology that makes the most sense for your business. Prices have dropped significantly in recent years, and today, all three technologies are available in compact, affordable systems.

Calculating costs does not end with upfront equipment costs. Material and labor costs have a significant influence on cost per part, depending on the application and your production needs.

Here’s a detailed breakdown by technology:

FDM V SLA V SLS

We hope this article has helped you focus your search for the best 3D printing technology for your application.

Explore our additional resources to master the intricacies of 3D printing, and dive deeper into each technology to learn more about specific 3D printing systems.

 

More information

Redstack offer both Ultimaker FDM 3D printers and Formlabs SLA 3D printers from store.redstack.com.au  Contact us today on 1300 667 263 for more information on which option will be best for your particular needs.

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