There is a struggle between two printing technologies; the Fused Deposition Modeling (FDM) and the Stereolithography Apparatus (SLA). The two methods are different, and each has its pros and cons.
Let’s go through their differences.
FDM vs. SLA: Basics
FDM is an additive method for 3D printing technology. In FDM, the 3D model is not created in one process like moulding, but by adding many layers of melted material building up a solid 3D model from the bottom up.
Like FDM, SLA is an additive method for 3D printing technology, and models are built layer by layer. However, SLA uses a curable photopolymer, typically a liquid resin that can be easily manipulated. The resin is hardened by the curing process,(applying focused light or UV light.)
Way of Working
In FDM, the user should give the printer a path to follow so that the deposited material can create the right object. One of the easiest ways to create a 3D object is by using a 3D model file like an STL or OBJ file. They supply the FDM with information on how to “slice” the object into layers that the FDM can apply one at a time.
Note: the more complex or small an object is, the finer it should be sliced. Not all FDM printers are qualified to print such complex objects.
The printer then heats the filaments and extrudes them through the nozzle one layer at a time. When the printer finishes this process, you should wait for some time so that the layers bond.
Then, the object is ready to use!
After giving the FDM the information it needs, the printer needs to have filaments usually made from safe plastic that could be easily moulded, heated up, and pushed into ropes or threads. The filaments could also be made from various raw materials that give the printed object additional properties
On the other hand, the process of SLA starts with the resin liquid and a UV laser that can be carefully directed at the bottom layer of resin.
The SLA printer uses a very complex file of instructions to know where exactly to direct the laser beam.
Typically, the printer includes a base for the 3D object to build onto. Then, to raise the object from the depth, the base moves through the tank of liquid as the object is built layer by layer.
Such layers vary from the FDM layers in that they are one hundred microns thin and form very quickly. Furthermore, they bond on a chemical level making the object one unified material, unlike the FDM whose filaments bond via melting.
FDM vs. SLA: Properties
Materials And Colors
Traditionally, FDM printers use PLA, PETG, or ABS filament. Most FDM printers can handle nylon, PVA, TPU and a variety of PLA blends (mixed with wood, ceramics, metals, carbon fiber, etc.) Filaments are available in various colors.
You can use standard filament rolls with a 1.75 or 2.85mm diameter. For better quality, use proprietary filaments, or expensive filament boxes.
However, SLA printers have a more limited palette of resin colors. They are often proprietary and cannot be exchanged between different printers.
The choice of colors is limited; formlabs offer black, white, grey, and clear resins. However, for industrial uses, they offer more durable and highly specialized materials like dental, heat-resistant, or flexible resins.
Smoothness And Precision
FDM printers use layers upon layers to create an object. The process by which layers are formed affects the surface quality, level of precision, and the accuracy of each layer, and consequently, the overall print quality.
Read more: 3D Printers for Miniatures – Simple Guide.
This is because layers may not fully adhere to one another. They are generally clearly visible on the surface, and the process cannot reproduce intricate details that SDL can offer.
If you decide to use SLA printers, you should know that they produce more accurate objects with higher resolution than that produced by FDM printers. This is mainly due to the small size of the optical spot of the laser or the projector, which consequently makes the resolution better.
Furthermore, there is not so much pressure applied to the object; therefore, the surface finish is almost always smooth. It produces fine details that FDM printers could never produce.
Adhesion After 3D Printing
In FDM, printed objects can be easily removed from the print bed. If they stick to the print bed, they could be removed using a palette knife.
In SLA, removing the printed model from the printing platform could be a complicated process, but it could be done using a palette knife.
Industrial printer manufacturer Carbon3D came up with the idea of using oxygen to prevent the resin at the surface of the model from hardening.
If you are using FDM, you need to remove excess plastic either with your fingers or with a cutting tool after printing.
You will also need to remove supports if the model has overhangs.
SDL printers often come with rubber gloves to protect your hands from resin and alcohol. You will come in touch with them because the printed models are usually covered in sticky resin that has to be removed in a bath of isopropyl alcohol.
Depending on the model, supports may be required as well, and the user can easily remove them as with the FDM printers.
FDM printers use the same standardized filament rolls whose prices have been declining for some time now.
However, SLA is expensive because the user has to replace the resin tank after 2 to 3 liters of resin have been printed since the tank gets smudged inside over time, so the light source is no longer able to project the image in the resin precisely.
The SLA user should also replace the build platform from time to time because it gets disfigured when the user removes the printed model.
FDM vs. SLA: Uses
1. If You Have a Home Printer:
They are affordable, easy to operate, and their material is available in the market.
2. If You Need Durability:
FDM objects can be used for various purposes. The improved filaments continue to make the printers more durable.
3. If You Need It For Learning Purposes:
It is the most suitable technology to use when teaching students how to code for 3D printing, or how to use your 3D printer.
1. If You Need To Print Details:
You should use the SDL when you need to create an object of accurate details.
2. If You Need Strength And Practicality:
The various photosensitive resins give the creators more options regarding qualities they would like to install on the objects.
Such objects are stronger than FDM objects, which makes them more practical.
3. If You Need It For Testing Purposes:
This is suitable for creating prototypes of products for testing purposes.
Also suitable for mass-producing specific components.
FDM vs. SLA: Cons
FDM printers struggle with fine details. They cannot create a high-end prototype.
Moreover, they need precise coding and calibration, or else the printer will not work correctly. In other words, you need to give the printer accurate information to teach it how to do a new project. They have limited design compatibility.
SLA still struggles with moving parts, no matter how proper the slicing and layering techniques are.
It is more complex to mess around and more expensive due to its resin and complexity.
Moreover, resins are proprietary, so you have less flexibility when choosing what you want to print with.
FDM is less costly and could be used if you do not care about the precision and accuracy of the object you want to create. However, if the price is not a problem for you, and precision and accuracy are of utmost importance, then go for the SDL technology.