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FDM vs. SLA vs. SLS vs. DLS: Battle of the 3D technologies

Introduction

Do you want to freshen up your memory or are you just new to the world of 3D printing and want to learn about the three classic 3D technologies? Look no further, we have most of the details available here.    

Choosing a 3D printing technology to print out a prototype, a proof-of-concept or any object at all will depend on what is expected out of the object. Each technology has their own set of strengths and weaknesses and will define the characteristics of the printed object. This week, we will be looking at three most used types of 3D printer technology: Fused Deposition Modeling (FDM)Stereolithography (SLA)DLS, and Selective Laser Sintering (SLS).

Choosing the right 3D printing technology for your project

Additive manufacturing applications are numerous, and you are now ready to make the most of this 3D printing technology. After spending some time choosing the right 3D software and creating your 3D files, you have to choose how to give life to your project. For rapid prototyping or production, additive manufacturing is the solution. But do you know which 3D printing technique you should use to develop your project? Indeed, we know that finding the right 3D printing technique and the right printing quality to manufacture your 3D objects is not that easy.
Do you want to get an FDM 3D printer, use SLA machines, or make the most of SLS industrial 3D printers using a 3D printing service? We will answer all your questions in this blog post. After this, you will finally understand what is the difference between FDM and SLA 3D printing techniques, and know how to use plastic or resin 3D printing.

Discover these 3D printing technologies

Fused Deposition Modeling (FDM)

FDM printer

Ultimaker 2

The most democratized additive manufacturing method, Fused Deposition Modeling works by extruding a thermoplastic polymer through a heated nozzle and depositing it on a build stage. FDM machines are the most affordable, especially for individuals that do not have a company’s budget. Many brands today are available pre-built like MakerBot and Ultimaker, two of the most popular desktop 3D printers, or can be built using DIY kits or going from the ground up and printing parts to create an FDM 3D printer.

 

The concept behind FDM printers is simple: a plastic filament runs through the nozzle and melts when in contact while being gradually deposited in a structured way on the printer bed until the object is finished. The plastic used in FDM filaments are generally ABS (Acrylonitrile Butadiene Styrene), PLA (Polyactic Acid) and Nylon (Polyamide), but other exotic varieties of materials can also be used, like a material blend of plastic and wood or carbon.

 

The FDM technology is a quick technique to manufacture your 3D project at home, but this technique won’t allow you to reach a professional or industrial result.

Stereolithography (SLA)

SLA Printer

Formlabs

Stereolithography was one of the first additive manufacturing technologies to be theorized and patented in the 80s. The concept behind it, though there are many variations today, is quite simple: a near-UV laser beam is focused and quickly draws a 2D section of the design on a thin layer of liquid photopolymer resin. The photosensitive resin polymer then reacts and solidifies forming a single 2D layer of the design. Depending on whether the laser comes from below (like the above image) or from above, the object is raised one layer depth while still in contact with the resin, or a new layer of resin is applied to the object, respectively. Then the process is repeated for each new layer of the design until the 3D printed object is complete. The final step is to clean the completed object soaked in resin and remove the eventual support structures.

 

SLA has also seen a popularity as desktop 3D printers but is usually sold pre-built like SLA 3D printer Form 2 from Formlabs or the Ember from Autodesk. FDM and SLA 3D technology are two really effective manufacturing methods. However, such printers are much more expensive than FDM printers, as their costs range from the thousands of dollars/euros ($3,499 for the Form 2, $5,995 for the Ember).

Carbon DLS Technology

Carbon M1 3D Printer

Carbon M1 3D Printer

This 3D printing technology works by projecting a continuous sequence of UV images, generated by a digital light projector, through an oxygen-permeable, UV transparent window, below a liquid resin bath. It creates a dead zone above the window which maintains a liquid interface below the part. Above this dead zone, the cured part is drawn out of the resin bath. This 3D printing technology was first introduced in February 2014. A few months later, the company Carbon 3D was created to commercialize it.

 

Thanks to the Carbon CLIP technology and their resin 3D printers, we can 3D print parts with high mechanical properties. These parts are as precise as SLA printed parts and can be 3D printed much faster thanks to the continuous process. Thanks to the engineering resins, you can obtain flexible material or a highly resistant one for technical parts, but also 3D printed parts with smooth surface. 

 

To learn more about the CLIP resins, you can visit our CLIP material page.

Selective Laser Sintering (SLS)

SLS-EOS-Formiga-P110

EOS Formiga P110

Last but not least, the technology mostly used at Sculpteo: Selective Laser Sintering. The concept is quite simple, but the execution is usually reserved to professional companies and online 3D printing services as ours, since SLS printers are usually large (as large as a double door American fridge) and costly. To summarize the idea behind it, a powder from a container is swept upon the build stage by a recoater, a laser then selectively scans the thin layer of powder, sintering together powder particles in the shape of the cross-section of the first layer of the design, as we can see in the image above. The build platform is then lowered one layer depth and the recoater applies a new coat of powder. Just like the first layer, the second cross-section of the 3D design is scanned and sintered while being adjoined to the first layer making a solid part. The process is iterated until the object is completed and the 3D part is built layer by layer. The tray containing the completed object is then removed, and the objects are de-powered. No further process is needed after the printing process, unless you want to apply any additional surface finishes (paint, polish, dye, smoothing beautifier…).

 

Compared to stereolithography and FDM, SLS does not require support structures since the powder acts as a self-supporting material. This allows intricate and complex geometries to be constructed, there is an almost complete design freedom. However, the cost of a machine is pretty steep, which is why it is mainly used for industrial applications. Sculpteo, however, has made it available for everyone!

Technical Characteristics

A lot can be said for each technology, as new printers come out every year with all new characteristics. However, to try to generalize trends, we set out to define a table with general terms and components to define each technology to enable everyone to choose between them according to their needs and wants.

FDMSLSSLACLIP
MaterialABS, PLA, NylonPolyamide (Nylon), Polystyrenes, Thermoplastic Polyurethane (TPU),MetalPhotosensitive ResinsSpecial Photosensitive Resins
Achievable qualityLow to MediumHighHighHigh
Layer thickness0.5 to 0.127 mm0.05 to 0.01 mm0.05 to 0.015 mm0.1 mm
Minimum wall thickness1 mm0.8 mm5 mm0.5 mm
Surface textureRough (“staircase” effect) but can be polishedSlightly rough but can be polishedSmooth, Often shinyQuite Smooth
Colors (without post-process)Opaque and translucent all colorsOpaque White, Gray and BlackOpaque and translucent all colorsDetermined by the color of the resin
Support (complex designs)RequiredNot requiredRequiredRequired
MechanicallyVariable (can be strong or flexible)Strong and flexibleStrong and brittle, New flexible compoundsDetermined by the engineering resin
Mechanical failureGradual deformation until fractureGradual deformation until fractureAlmost no deformation until sudden fractureDetermined by the engineering resin
Abrasion resistanceVariableSuperiorVariableDetermined by the resin
Post-processPolishing, Painting, Sealing, Smoothing (with acetone vapor)Polishing, Smoothing Beautifier, Varnishing, Dyeing, PaintingPolishing (rarely needed),PaintingPolishing (rarely needed),Painting
Food compatibilityLeakage due to micro-gapsYesOnly with special resins (can be expensive)No
Chemicals compatibilityLeakage due to micro-gapsHighly resistant (Nylon)Not definedNot defined
CostPrinters inexpensive,Material inexpensivePrinters very expensive,Material inexpensivePrinter medium priced,Resins can be expensivePrinter Expensive,Resins can be expensive

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