Hello Machine Bros!
Now the question is: FDM or SLA: Which 3D printer to buy?
Perhaps just as it happened to me in my early days, you are looking to start in this fascinating world of 3D printing. So, you may be having a hard time deciding what type of 3D printing technology to use.
Among the various types of 3D printing technology, the following two methods currently stand out greatly: FDM and SLA.
Therefore, whether you are just starting out in this world of 3D printing, or you are already using one of the 3D printing methods, but you want to learn more about other forms of 3D printing, this article is for you.
¿What is the FDM Technology?
The FDM (Fused Deposition Modelling) technology is a technique that consists of depositing flat layers of molten material superimposed on each other, to achieve an object with volume.
In short, they are called FDM 3D printers that print layer by layer, from the casting of plastic filament, making use of an extruder.
¿What is the SLA Technology?
The SLA (StereoLithography Apparatus) technology is a process that uses the photopolymerization principle to create 3D pieces from resins sensitive to UV (Ultraviolet) rays. The material solidifies layer by layer through the passage of a laser.
In summary, SLA 3D printers or also known as resin 3D printers, are those that print from solidifying resin, layer by layer, using a UV laser.
If you still don’t understand well the operation of any of these 3D printing technologies, then, next will find two videos to help you understand these technologies a little better.
| Note: Resin 3D printers, which are becoming more common on the market, are of the LCD type. These base their operation in the same way as SLAs, except that, instead of using a laser to solidify the resin, they use an LCD (liquid-crystal display). |
If you want to know about other 3D printing technologies, we recommend you to check the article What is 3D Printing?
Now that we have more insight into what each 3D printing technology does, let’s now talk about the 3D printers.
FDM Printers VS SLA Printers
To compare both types of 3D printers, we will look for a common point between both types of technologies, in our case, it will be the price of the 3D printer.
Which will serve as a basis to compare the print volume obtained by two 3D printers of similar prices, but using the two printing technologies SLA and FDM.
| Important note: Prices may vary according to your location or discounts applied by the shop. |
3D Printers between $200 and $300
| Technology | Printer | Printing Volume (millimeters) (inches) | Price (USD) |
| FDM | Creality Ender 3 | (L x W x H) 220 x 220 x 250 mm 8.6 x 8.6 x 10 inch | |
| SLA | ELEGOO Mars 2 Pro | (L x W x H) 130 x 82 x 160 mm 5.1 x 3.1 x 6.3 inch |
3D Printers between $300 and $600
| Technology | Printer | Printing Volume (millimeters) (Inches) | Price (USD) |
| FDM | ANYCUBIC MEGA X | (L x W x H) 300 x 300 x 305 mm 11.8 x 11.8 x 12 inch | |
| SLA | ANYCUBIC Photon Mono X | (L x W x H) 192 x 120 x 245 mm 7.55 x 4.72 x 9.84 inch |
3D Printers of more than $600 USD
| Technology | Printer | Printing Volume (millimeters) (Inches) | Price (USD) |
| FDM | QIDI TECH X-Plus | (L x W x H) 270 x 200 x 200 mm 10.6 x 7.9 x 7.9 inch | |
| SLA | Phrozen Sonic Mighty 4K | (L x W x H) 200 x 125 x 220 mm 7.9 x 4.9 x 8.7 inch |
We can see that FDM 3D printers have a higher volumetric capacity than similarly priced SLA 3D printers.
Consumables for 3D Printers
In the case of FDM printing, we need filament coils, which usually come in 1Kg presentations and 1.75mm or 3mm diameters.
On the other hand, SLA printing uses light-curing resins that usually come commonly in 500mL and 1L presentations.
Both FDM and SLA printing have different types of materials, so I will show you some technical characteristics.
It should be noted that both FDM and SLA technologies have the possibility of printing in various colors.
Filaments for FDM 3D Printers
Next, we will show you a table that contains the technical specifications of the most used filaments.
| Material | Max. stress supported (Mpa) | Defo- rmation temp. °C (°F) | Rigidity (Scale) | Durability (Scale) | Printability (Scale) |
| PLA | 65 | 52 (125) | 7,5 | 4 | 9 |
| ABS | 40 | 98 (208) | 5 | 8 | 8 |
| PETG | 53 | 73 (163) | 5 | 8 | 9 |
| TPU | 26-43 | 60-74 (140 – 165) | 1 | 9 | 6 |
| Nylon | 40-85 | 80-95 (176 – 203) | 5 | 10 | 8 |
Resins for SLA 3D Printers
We could start listing the types of resin according to their application:
- Standard resin: It is used for general prototyping.
- Engineering resin: It has specific improvements in terms of its mechanical and thermal properties.
- Flexible resin: As its name implies, this resin is more flexible than the others.
- Medical and dental resin: They have biocompatibility certificates.
- Castable resin: This type of resin leaves no residue after casting, it is commonly used in jewelry applications, to be used in a process known as investment casting or lost wax process. If you want to go deeper into this topic, I will leave you two links and one video: Link 1, Link 2, video.
Below you will find a table showing certain mechanical and thermal properties of some resins used in 3D printing.
| Resin Type | Maximum stress supported (Mpa) | Deformation temperature (°C) |
| Standard | 62 | 70 |
| Engineering | 91 | 128 |
| Flexible | 5 | 60 |
| Castable | ||
| Dental | 46 | 61 |
| Note: Not all 3C printers can work with all materials, there are materials that will require specific conditions or additional conditions to be processed, to obtain a well-made print, therefore, 3D printers with better performance would be required. This includes both FDM technology and SLA technology. It is worth mentioning that the SLA printers that are more accessible for an average user economically speaking, are those that use standard resin. |
SLA 3D printers have two other consumables apart from the resin.
The tank, which must be changed approximately after every 3 or 4 liters of use, this has an approximate cost for the ELEGOO Mars of $25 USD each tank.
The other consumable of SLA is the platform, although it is not so common to have to replace it every so often, this is usually damaged as the printed parts are removed from it. The platform for the ELEGOO Mars has an approximate cost of 64.99 USD.
If you want to know more about the other types of resin, check this link.
Performance Comparison Between an FDM and SLA 3D Printer
Now let’s compare the performance of the two technologies.
We will start by choosing common printing materials to study 3D printing costs, thermal and mechanical properties (Theoretical), equipment costs, material costs, among others.
First, let’s do an STL file created by ourselves, which we will analyze in the Simplify3D software.
The model volume is 34.6 cc, this is calculated knowing that the density of the PLA (for which the slicer is configured, at this time) is 1.24gr/cc.
We know that the volume can be easily calculated by dividing the mass (42.91gr value given by the software) between the density, that is 42.91/1.24 Which gives a result of 34.6 c.c.
| 3D Printer | 3D Printer price | Material price | No. of models that you can print (theory) | Material printing cost | |
| FDM | Creality Ender 3 Printing vol.: 12.100cc | 23 pieces (with 1Kg of material) | 1,15USD (each piece) | ||
| SLA | ELEGOO Mars 2 Printing vol.: 1.548cc | 28 pieces (with 1L of material) | 1,64USD (each piece) |
Regarding other variables such as printing time and finishing, generally the finishes and precision tend to be better in SLA 3D printers.
Regarding 3D printing times, this depends on many variables, among them the performance of the 3D printer, and the quality with which you want to print.
Therefore, we show you the following information obtained from apm-designs, where they mention that the printing times would be approximately these:
- FDM: 0,76-4,32 cm/hr
- SLA: 0,76 – 1,78 cm/hr
3D Printing Post-Processing
Once the 3D printing is finished either in FDM or SLA, there is still work to do.
FDM Technology Post-Processing
- Mandatory:
- Allow the hotbed to cool until you can easily remove the 3D print without damaging the bed or print.
- Remove the supports.
- Allow the hotbed to cool until you can easily remove the 3D print without damaging the bed or print.
- Optional:
- Smooth the model by using solvents or sanding (depending on the material).
- Apply annealing (heat treatment) or sealing (with epoxy resins) to give better thermal and mechanical properties to the 3D print.
- Paint the model.
- Smooth the model by using solvents or sanding (depending on the material).
SLA Technology Post-Processing
- Mandatory:
- Remove the model from the printing base (which is usually more difficult than in FDM printing).
- Dip the model in the solvent (usually isopropyl alcohol) to remove the excess liquid resin.
- Clean the printing base, although this does not have to do with the model treatment, it is important to remember to clean the printing base with solvent (Normally isopropyl alcohol).
- Drying of the model, in order to remove the remains of the solvent.
- Post-curing the model, this is not mandatory for the standard resin but highly recommended, as it greatly improves the thermal and mechanical properties of the print. For example, you can increase the tensile strength from 38Mpa to 65Mpa, and the deformation temperature from 42 °C to 58 °C. Post-curing consists of applying ultraviolet rays and/or heat for a certain time.
- Removing the support material, it is advisable to do this after post-curing, since the print is exposed to light and heat without the support material could deform the model.
- Remove the model from the printing base (which is usually more difficult than in FDM printing).
- Optional:
- Sand to remove marks from the supports.
- Paint the model with the desired color.
- Apply acrylic varnish against UV rays, to give the model a greater resistance against UV rays.
- Sand to remove marks from the supports.
In this link, you will be able to observe a detailed and graphic explanation of the post-processing of the parts manufactured with SLA.
Also, in this other link you can see some post-processing that can be applied to the PLA printed by FDM and in this other link, you will find a basic guide to painting your model 3D printed in an FDM printer.
Advantages & Disadvantages of Both Technologies
FDM
Advantages
- Use fewer consumables.
- FDM 3D printers tend to have a higher print volume, for the same price.
- More economical to print a model.
- More variety of materials, being able to choose materials with better mechanical and thermal properties without reaching significantly high costs.
- It is generally easier to remove the pieces from the heated bed.
- By changing the extruder to larger diameters allowable by the printer, shorter printing times are obtained.
- Fewer mandatory post-processing.
- Greater resistance to ultraviolet rays.
- Less support material is required.
Disadvantages
- Less smooth, aesthetically less attractive finishes (by not applying any post-processing).
- Less accurate impressions.
- Generally lower quality prints.
SLA
Advantages
- Better aesthetic finishes.
- Smooth surfaces.
- More accurate impressions.
- Generally higher quality prints.
Disadvantages
- They use more consumables
- SLA printers tend to have a lower print volume, for the same price.
- The standard resin is more expensive than a common filament.
- Acquiring more resistant resins both mechanically and thermally is more expensive, in addition to this, the simplest SLA printers will not be able to use the resins that offer these best properties.
- More expensive to print on this technology.
- It is generally more difficult to remove impressions from the bed.
- Printing times may be longer, under certain conditions.
- Lower resistance of the pieces to UV rays (although it can be improved by applying post-processing).
- Generally, the pieces require more support material.
- More mandatory post-processing.
| EXPLANATORY NOTE: This comparison is made assuming that we are analyzing two printers (One FDM and one SLA) of similar prices. |
Some of the Most Popular Slicers for 3D Printing
Slicers for FDM printers
- Cura (Free)
- Simplify3D (Paid)
- Slic3r (Free)
- KISSlicer (Free and paid version)
Slicers for SLA printers
Which Technology to Choose Between FDM and SLA?
If you are looking for precision, quality, a smoother and more aesthetic finish, SLA printing is for you, although it will be a more expensive investment, with more consumables and depending on the chosen 3D printer, you may or may not choose to use better performance resins (the which also have a high price).
If you are looking to print more economically, with higher print volumes, better print times, fewer consumables, and accessibility to greater varieties of materials, FDM printing it’s your best option.
Conclusions About FDM vs SLA
In summary, for the same level of print volume, FDM printers are cheaper than SLAs.
Printing material is also cheaper for FDM than for SLA, also the SLA requires a greater quantity of consumables. We could mention that to 3D print with materials that give greater mechanical and thermal properties, it is more economical to purchase an FDM printer.
When it comes to print quality and accuracy, SLA printers generally have the upper hand in this. Since they give products with a higher resolution and with dimensions that are more similar to the real CAD. SLA prints require more laborious post-printing treatment than prints made with FDM.
Each printing technology has its advantages and disadvantages, each has its time and use for which it performs best. We could even say that one could be complementary to the other.
But technology is constantly advancing. So, this gap that separates the pros and cons of both 3D printing technologies could be narrowed further and further.
For example, in the past acquiring an SLA printer was extremely expensive, a common user could not get one, the same was for acquiring resins and other consumables.
I hope this article has been useful to you and will help you decide what type of technology to use to materialize your designs.
so, FDM or SLA: Which 3D printer to buy? Hope you find here your answer and if you have any questions about this subject, let us know in the comment section!
Cheers.
See you soon Machine Bros!
