3D Printer: FDM and SLA Printing Technology

FDM and SLA are two different production methods in the field of 3D printers.

What is FDM and SLA?

FDM stands for Fused Deposition Modeling . In FDM 3D printers, thermoplastics, i.e. filaments, are heated to a fluid consistency by the hot print tip extruder to create the 3D model. The molten filament is then laid layer by layer in the print area to create the model.

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FDM is a widely used type of 3D printer, as it is an FDM 3D printer for every budget, as well as because the filaments are inexpensive.

SLA is an acronym for Stereolithography Device or stereolithography for short. Like FDM, the SLA 3D printer is built layer by layer in models. However, SLA 3D printers use a photopolymer (typically a liquid resin) that is hardened by applying focused light or UV light (this process is called curing). SLA 3D printers usually build models from top to bottom, and the construction platform lifts the model upwards and removes it from the resin bath.

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The light source is a laser or a digital projector, and this technology is commonly called DLP, Digital Light Processing. Lasers "draw" layers, and an entire slice of the model (a two-dimensional layer) is projected into the resin bath at once.

Laser SLA 3D printers are generally slower than DLP models due to the small surface of the laser beam. In DLP printers, each layer hardens faster because the entire image of a layer is reflected in the resin. What's more, DLP projectors use the same technology as work and home theater projectors, so they're safer and easier to maintain than customized laser systems. However, the printed models must undergo a final process.

In general, SLA 3D printers are more expensive than FDM 3D printers. Although the prices of resin 3D printers have fallen in recent years, they are generally preferred for specialized productions.

Materials and Colors

FDM 3D printers typically use PLA, PETG or ABS filament. Most FDM 3D printers use nylon, PVA, TPU and various PLA mixtures (wood, ceramic, metal, carbon fiber, etc.). Mixed with) can use. Filaments are available in a variety of colors. Some manufacturers even offer a service to produce RAL colors on demand.

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Most FDM 3D printers can use standard filament rolls available in two standard sizes (diameter: 1.75 mm or 2.85 mm) from various sources. Several 3D printers make their own brand filaments available. These are usually more expensive than standard filaments, but often provide much better quality.

Owners of SLA 3D printers have only a more limited variety of resin material. It cannot be switched between 3D printers from different manufacturers. Color selection is also limited. Formlabs, for example, offer only black, white, gray and transparent resins. On the other hand, it also offers more durable or very special materials for industrial uses such as dental, heat resistant or flexible resins.

Precision and Smoothness

In FDM 3D printers, the resolution of the printer is a factor in the sensitivity of the size of the nozzle and the movements of the extruderX-Y axes. The sensitivity and smoothness of printed models are also affected by other factors. Because the bonding force between layers is lower than SLA printing in FDM prints, and the weight of the top layers can compress the following layers, a number of printing problems may occur (e.g. Lifting the edges of the part (warping), misalignment of layers, shifting of layers, shrinkage of the lower parts, etc.

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SLA 3D printers can continuously produce higher resolution objects and are more precise than FDM 3D printers. The reason for this sensitivity is resolution. First of all, the optical point size of the laser or projector is really small. In addition, less force is applied to the model during printing. Therefore, the surface quality is much smoother. SLA 3D printers can produce details that an FDM 3D printer can never produce. These fine details are the main reason why you should consider getting the SLA 3D printer.

Surface Treatment

After printing to a model FDM 3D printer, you need to remove the supports and excess plastic with your fingers or crowburn. Sanding helps you achieve smoother surfaces.

An isopropyl alcohol bath is performed to remove excess resins from models printed on an SLA 3D printer such as Form 1+. Therefore, you should buy rubber gloves along with the SLA 3D printer to protect your fingers from resin and alcohol. Depending on the model, support may also need to be produced. Removing these supports is as easy as FDM 3D printers.

3D Printing Costs

Consumables in FDM 3D printers are nozzles and filaments. As mentioned earlier, most FDM 3D printers use the same standard filaments, and filament prices have been falling in recent years. You can buy 1 kg of PLA filament for $15. Of course, special filaments are also more expensive.

In SLA 3D printers, not only resin is consumed. In SLA 3D printers, the resin tank must be replaced after printing 2-3 liters of resin. This is due to the staining of the tank inside over time. Thus, the light source can no longer fully reflect the image to the resin. Depending on the manufacturer and model, resin tanks will cost you about $80 to $100. Another component that needs to be replaced from time to time is the construction platform. This platform can cost you up to about $150. Resin costs are also $150 – $250 for 1 liter of standard resin.

Which One To Use?

In summary, if high precision and smooth finishing are your first priority, and the cost for a print job is not important or not very important, use an SLA 3D printer. Use an FDM 3D printer if the cost is significant.

When to Use an FDM 3D Printer?

  • Rapid prototyping
  • Producing low-cost models
  • Perfect for hobbyists and makers
  • If precision and surface quality are not very important

When to Use an SLA 3D Printer

  • Complex details and/or a very soft surface quality are important
  • When the robustness and durability of the model is not very important (models made of resin can be damaged when exposed to the sun for a long time)
  • To create casting molds to facilitate mass production (e.g. for jewelry or toy manufacturers)

When to Use 3D Printing Service?

There's a third option to save your money. You don't need to buy a 3D printer to print something. You can use 3D printing services. More information about 3D printing service can be found here.