Guide: 3D printing technologies: FDM vs. SLA

If you are already familiar with 3D printers , especially from China, you may already have had impressions and experiences with FDM 3D printers. Moooment. FDM? What does that actually mean? Are there any alternatives at all? Yes there is! And that is SLA 3D printer. In this area, the Chinese 3D printing manufacturers are currently doing a lot of pressure (* bada-bum-tss *). You can expect 1-29 SLA 3D printer tests from me in the future. What does SLA mean, where and above all how is the printing process used? What are the differences? This is a little guide to get you started .

[image; sla fdm comparison]

FDM stands for Fused Deposition Modeling and is basically always the same: plastic filament is melted and extruded and stacked layer by layer through a pressure nozzle. It doesn’t matter whether the layers are printed by shutting down the heating bed or by powering up the hotend. The standard thermoplastics are mostly PLA, ABS, HIPS or PETG. FDM 3D printers are mainly known from the hobby area, as they are always cheaper, more reliable and easier to use.

SLA stands for stereolithography and is – even if it was the first 3D printing process worldwide – to be found more in the advanced to professional area. Until now! The Chinese 3D printer manufacturers are now increasingly daring to use SLA printing technology and the price is falling. In the stereolithography process, liquid resin is hardened at certain points using a laser or LEDs, so that the desired shape is created. This process is also called photopolymerization.

But which method is better now? Which one more precisely? Which one is faster? And which process is more cost-effective?

What is the benefit of 3D printing with Fused Deposition Modeling (FDM)?

FDM 3D printers are fed with filament made of PLA or ABS, for example. This is usually available with two diameters (1.75 mm or 3 mm) on large rolls of up to 5 kg, with the 1.75 mm diameter filament becoming more and more standard. This filament is fed through a stepper to the hotend and heated there. Depending on the material, the hotend is between 190 and 260 degrees.

 

[fdm pressure structure image]

The hot filament is pushed on and pressed through the nozzle. This can have different diameters; 0.4 mm is a common value – the larger the diameter, the coarser the printed image. It is important that the liquid filament is cooled again immediately after the nozzle so that it does not flow.

In principle, you can compare this to a primitive (but accurate) hot glue gun . When one level has been completely covered, the hotend is raised by 0. x millimeters and the next level is filled. After usually hundreds of levels, the 3D printing is finished.

  • Filament costs: ~ 20 € for 1 kg
  • Device costs: 3D printers from China are available from ~ € 50
  • easy to maintain and modding
  • generally low operating volume
  • Print speed (depending on the type)
  • scales better in size / purchase price
  • Operating volume (3-4 steppers make “noise”)
  • high temperatures are required (= high power consumption)
  • Accuracy / resolution is “average”

Since it is “just a better hot glue gun”, it may also become clear why rebuilding / adding / tuning an FDM 3D printer is “relatively” easy. Aside from electronics, it is relatively primitive mechanics. And the most important thing here is to reduce vibrations. The Anet A8 has, among other things, triggered a 3D printing trend. Extremely inexpensive (at that time less than € 200) and relatively accurate. Of course, we also tested the Anet A8 3D printer .

Popular FDM 3D printer from China

So far we have tested almost 50 different FDM 3D printers from China. These are my three favorites, but also the favorites of the community.

  1. Anycubic I3 Mega for ~ 250 €: metal frame, 2 Z-axes, touchscreen and installation space of 210 x 210 x 205 mm
  2. Creality3D CR-10 for ~ 350 €: 3D printer with a very large community and installation space of 300 x 300 x 400 mm
  3. TEVO Little Monster for ~ 650 €: Very large Delta 3D printer with an installation space of 340 x 340 x 500 mm

Please note: There are of course other great 3D printers from China. So there are z. B. big differences in the design (Prusa i3 (Cartesian)), delta printer, cube design, etc.

What is the benefit of 3D printing with stereolithography (SLA)

Stereolithography, while seeming more complex at first, is actually the older technology . This was already in use at the beginning of the 1980s and is still used more in the professional sector. In the past, the liquid resin was usually hardened with a laser, but now there are more and more low-cost solutions with powerful UV LEDs.

 

{sla pressure build up image]

Hopefully, the graphic above illustrates (and simplifies) the printing process well. The Z-axis is immersed in the resin bath and the mirror directs the laser beam to the area to be cured. The Z-axis slowly moves up over time and dips the print object into the resin again and again.

  • The resolution is, depending on the type, very, very precise
  • low operating volume
  • low heat and power consumption
  • Often less space is required for the entire device
  • Resin costs: ~ 50 € for 500g
  • not easy to repair or no “DIY kits”
  • further accessories (UV hardener) required
  • undetectable danger (laser!)
  • Installation spaces are small

Formlabs is certainly one of the pioneers in low-cost SLA 3D printing for beginners and to see the process in action, there is a small explanatory video here .

Small conclusion: which 3D technology should I use when?

Currently, FDM 3D printing is still clearly ahead in the hobby area. There are hundreds of different models (really!), Mountains of experience, further development is easy and the filament is cheap.

sla 3d print
Including Kristian from an SLA 3D printer. Pay attention to the details of little Darth Vader!

Resin is still relatively expensive. In addition, the printing areas are relatively small. And yet: Anyone who really wants very precise 3D prints on a small scale will no longer be able to avoid SLA 3D printers in the future.

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