Choosing a 3D printing technology: FDM, SLA and SLS. Functional and visual characteristics

Comparing FDM, SLA, and SLS 3D Printing Technologies. Choosing the Right 3D Printing Technology

Choosing a 3D printing technology. In today's world, 3D printing is applied across many industries, from engineering to manufacturing, dentistry, healthcare, jewelry, and much more. 3D printing technology offers a wide range of applications, from visual and functional prototypes to end-use parts.
Each of the 3D printing solutions existing on the market has its own advantages and limitations. This makes each technology more suitable for certain purposes than others.

In the process of selecting a 3D printer, you will need to determine the technology that best meets your requirements. Let's compare the functional and visual characteristics of the three most common plastic 3D printing technologies: FDM, SLA, and SLS.

Choosing the right 3D printing technology and material with the correct functional properties is crucial to ensuring your parts function as intended.

1. Build Volume Dimensions and Reproduction Accuracy (Tolerances)

Let's start with the dimensions of the build area.

The most common FDM printers offer a print volume with a cube side of about 200 mm, while large-format options reach sizes of 300 * 300 * 600 mm.

As with FDM, professional desktop SLA printers can come in standard or wide-format models. Most standard sizes are cubes with a 200 mm side. Larger models can offer a build area 5-10 times bigger.

The build volume of desktop SLS printers is comparable to standard FDM and SLA printers.

Build area dimensions in different 3D printing technologies:

The next thing to consider regarding functional properties is tolerances. If your parts require tighter tolerances and higher precision, then SLA and SLS are your best options. Both technologies use high-precision lasers to form each layer of material with reliable and repeatable results.

Reproduction accuracy (tolerances) in FDM, SLA, and SLS 3D printers:

2. Choosing 3D Printing Technology: Material Properties

Moving on to material properties. FDM and SLA offer a wide range of materials with properties comparable to common injection-molded plastics.

The choice of materials for SLS is more limited. However, this technology is the best choice for durable products and functional machine parts. The most common material for SLS 3D printers is Nylon—a high-performance engineering thermoplastic. SLS Nylon parts possess high thermal resistance.

FDM 3D printers use thermoplastic filaments such as ABS, PLA, and various blends.

SLA printers create plastic parts from various resins, each designed to match the characteristics of conventional plastics. SLA 3D printers offer the most flexible material choice. For instance, they use flexible and soft materials similar to silicone. Additionally, SLA printing offers materials with an operating temperature of up to 238 °C. Finally, SLA printers provide the widest selection of biocompatible materials for dentistry and medicine.

Furthermore, desktop 3D printers can be used to create metal parts by casting 3D-printed plastic patterns. SLA is a widely used technology for 3D printing investment casting patterns for jewelry, dentistry, and engineering applications, while FDM also offers several experimental options.

If you have specific requirements for strength, elongation, stiffness, durability, or other properties, we recommend reviewing the technical data sheets for each specific material.

Variety of printable materials in FDM, SLA, and SLS 3D printers:

3. Choosing 3D Printing Technology: Visual Characteristics of Printed Models

For applications such as conceptual, artistic, or commercial models and prototypes, you should choose the technology based on the appearance and visual characteristics of the parts produced by these technologies.

In FDM 3D printing, layers are extruded by a nozzle that lacks the control and ability to reach the level of detail offered by the other two technologies. This is why FDM prints usually have clearly visible layer lines.

Thanks to the use of high-precision lasers, SLA and SLS are the gold standard for producing high-quality materials and models with complex detailing and excellent characteristics. In SLA, the laser controls light with high precision. Each layer has smoothed edges. Due to this, each new layer aligns better with the previous one. This creates a smoother surface straight out of the printer with a reduced "stair-stepping effect," especially for models with thin protruding details. SLA is the gold standard for producing high-quality materials and models with intricate detailing.

SLS printers also use lasers to obtain high-detail products. However, because the lasers work by sintering powder material, the parts come out of the printer with a rough, grainy surface.

Visual appearance of parts printed on 3D printers using different technologies:

Parts printed on a 3D printer can also be sanded, polished, primed, and painted. This allows you to achieve the desired visual look.

Post-processing of SLS parts is the simplest because there are no printed supports to remove from the printed parts. SLA parts require some sanding to remove support marks when printed with supports. Meanwhile, FDM parts require significantly more sanding and polishing before priming and painting to obtain a high-quality finish.

Filaments are available in a vast variety of colors. In contrast, some SLA resins can be mixed with color pigments to obtain almost any custom color. Finally, SLA has the unique ability to create translucent or even optically clear parts. SLS parts can be dyed in various colors.

FDM, SLA, and SLS 3D printing offer a multitude of materials and options that best meet the functional and visual requirements of your application. In many cases, you may find that two or even all three technologies are suitable for your needs. In this event, you should prioritize your requirements. Additionally, you should weigh other factors such as speed, cost, workflow, or ease of use.

This is one of four articles helping you make the right 3D printing technology choice for your needs. See also other materials on this topic:

How to Choose Desktop 3D Printing Technology: FDM, SLA, and SLS. Speed

How to Choose Desktop 3D Printing Technology: FDM, SLA, and SLS. Price

What is "Resolution" in 3D Printing?