3D printing has undergone a huge increase in popularity across the past few years. This is in part thanks to filament 3D printers becoming much more accessible, both in terms of cost and use-ability.
More recently SLA 3D printing has started to challenge FDM filament 3D printers in terms of popularity. And one of the main reasons for this is a boost in both print quality and the large roster of materials available to print with.
In this guide, I’ll run you through an in-depth comparison between FDM vs SLA 3D printers. This is the ultimate filament vs resin 3D printer comparison.
FDM vs SLA – The Basics
When we talk about FDM 3D printing, we’re talking about filament printers. These were the first home 3D printers to break on to the market all those years ago. An FDM 3D printer essentially uses heat to fuse layers of plastic filament together in a pre-defined pattern.
SLA 3D printing on the other hand, utilises light instead of heat. The printing material is different to FDM, as SLA uses a liquid resin. This resin is also built up layer by layer, just like the FDM method. However the liquid resin is hardened using a laser.
What is FDM Filament 3D Printing?
FDM 3D printing is an abbreviation of Fused Deposition Modeling, and is without a doubt the most popular method of consumer 3D printing. FDM printing uses relatively inexpensive plastic filament, which is a essentially a thin fibre of plastic. The low cost of the filament itself is one of the reasons why FDM printing is so popular.
During the 3D printing process, an FDM printer creates layers of filament by forcing it through a heated nozzle. This filament is initially melted onto a printing bed which is used as the base of the object. Then the rest of the 3D model is built up in layers, a single layer at a time. This process is what gives filament 3D prints that classic layered texture before the smoothing process.
Both filament 3D printers themselves, and the spools of plastic filament are relatively low cost. This makes filament printing the most popular and widely used consumer 3D printing technique in the world.
You can view the best budget 3D printers here.
What is SLA Resin 3D Printing
SLA 3D printing is an abbreviation of Stereolithography Apparatus. SLA printing hasn’t traditionally been the most popular method of consumer 3D printing, but has been widely used in commercial scenarios.
However, over the past few years, SLA printing has become much more affordable. And you can find a fair few SLA 3D printers for similar prices as FDM printers.
Similarly to the method FDM printers use to form a model, SLA printers also build models a single layer at a time. However, SLA printers use a laser or UV light to harden (cure) liquid resin.
This method makes use of a precision laser to draw each layer of a model within the liquid resin. Essentially, where ever the laser hits within the liquid resin is hardened. These hardened areas form the model.
As I previously mentioned, SLA printing hasn’t typically been as budget friendly as FDM printing. Although, there are a good selection of budget friendly SLA 3D printers which put it very close to an FDM printer in terms of cost.
FDM vs SLA 3D Printing Comparison
Below I’ll compare filament and resin 3D printers in a variety of categories. These categories below are all important factors when looking to purchase a 3D printer.
Print Quality
My last FDM vs the SLA (half size) pic.twitter.com/crOVjbIYbU
— arturo182 (@arturo182) October 14, 2020
Both types of 3D printer use a similar layer by layer technique. However there are distinct differences in the results that are produced, which all affect the overall quality of your model.
FDM 3D printers form there models by extruding melted plastic through a nozzle, depositing it on the print bed, or the layer beneath. Due to the use of heat to melt the plastic, and also form the bond, there are a few factors which can negatively affect the overall quality.
The first being that it isn’t uncommon for layers to not adhere to each other correctly. This can cause models to break apart when handled. And also there can be small voids of air in between layers as the molten plastic is deposited. Again this can lead to overall instability.
Even once you conquer all of the potential issues above, the overall quality of FDM prints can still be lacking. You will always visibly notice each layer in an FDM 3D print. This can always be sanded away in the post-production phase.
SLA 3D printing does away with the heat element by using light to harden the liquid resin. By removing the element of heat you effectively remove the main variable which can cause warping or expansion and contraction artifacts which can occur in FDM printing.
By using a precise laser rather than a nozzle, SLA machines can form each layer of the model with much higher precision. This increase in precision also allows for much finer and smoother details when compared to FDM 3D printing.
SLA also differs from FDM by creating a chemical bond between layers due to the different curing method. This allows SLA prints to be completely water tight with no air pockets between layers.
Winner – SLA
This category is possibly the easiest to call, as SLA 3D printing has so many pros over FDM when we talk quality alone.
Print Speed
Speed of printing can be highly variable based on a number of factors such as model design, material used etc. However, in this guide I’m going to look at the most common FDM vs SLA printing method.
And with the most popular consumer 3D printers, FDM 3D printing will be faster most of the time.
This is due to the fact that the precision laser used in SLA machines covers a much smaller area than the nozzle of an FDM printer. While this does allow much higher precision, it does mean the SLA 3D printer will typically take longer to print the same surface area.
There are forms of SLA printers such as DLP and LCD machines which will increase the speed, and are even faster than FDM printers. These differ from a consumer SLA 3D printer by curing your model a whole layer at a time. This removes the need for a laser, and therefor speeds the whole process up.
Winner – FDM
9 times out of 10, an FDM 3D printer will be faster to print a model than an SLA 3D printer. However, if you increase your investment, there are SLA machines which can print much faster than FDM. Just remember, the post-processing of a resin print also takes much longer than with an FDM print, so you’ll also need to factor in this extra added time too!
Useable Materials
Consumer FDM 3D printers almost exclusively use a range of plastic materials. These most commonly include ABS and PLA. However, there are also forms of nylon which can be used in 3D printing, although these are more commonly found in commercial engineering.
When it comes to different colours, the options with FDM printers is vast. Because these 3D printers are so widely used in consumer situations, the desire for different colour filaments is large. This means that if you fancy a model in a certain colour, you can probably find a filament that fits the brief.
SLA printing on the other hand allows for a variety of material properties to be printed. However, most consumer SLA 3D printers are very restrictive in the materials that they allow.
In a professional environment, materials such as glass, wax and ceramics can all be used in SLA printing. This very much opens up the process of 3D printing to really provide bespoke solutions in an engineering scenario. And this is one of the reasons that SLA 3D printing is more popular with engineering companies than FDM.
When it comes to consumer products, most SLA printer manufacturers really restrict the type of materials you can use. Most consumer SLA printers have lasers which are designed to only cure a specific type of material. And even when it comes to colours, there are more restrictions in place. Creality for example, only offer their resins in 6 colours.
Winner – SLA
Despite some consumer SLA printers restricting users by only offering a single type of resin, in only a few colours. I still have to give the win to the SLA 3D printer. This is simply due to the amount of different material types that can be printed using a resin 3D printer.
I’m sure that in the future, these materials will become more widely used in consumer products. Whereas filament 3D printers are already restricted to a certain material palette.
Ease of Use
When we start to look at the ease of use, we have to really break down the printing process. The first part of the process, the modelling and prep is generally very similar no matter which form of printing you use. Some brands have their own software to help with the process, but other than this, this part of the process is pretty similar.
When it comes to preparing the machines to print, SLA printers do tend to come with a higher learning curve. You have to undergo a slightly more complex procedure to ready the machine to print. Whereas an FDM 3D printer only requires a simple setup.
During the printing process, most consumer 3D printers can run completely independently. You can leave them to print throughout the day and night without attending them. The only part you may need to intervene with is to ensure your material source doesn’t run out. Although some SLA printers do come with cartridges which allow for automatic refilling during the process.
The final part of the process is the post processing. This is the part of the process which is most different between FDM vs SLA. Once an FDM print is complete, you have the process of cutting away any supports, and then you can move straight on to finishing your model by sanding and painting.
An SLA print on the other hand requires a more complex process. You’ll have to ensure you rinse your model thoroughly to wash away any excess liquid before moving on to curing. To ensure your SLA print is as sturdy as possible, you will have to cure it under a UV light. This curing process will harden your model, which will then allow you to move on to the finishing touches.
There are products which will handle the washing and curing for you, but these come at an additional cost. And will require extra investment on top of the cost of the SLA printer itself.
Winner – FDM
Both FDM and SLA 3D printers use a reasonably similar process from modelling to printing. However after you’ve finished printing, your filament printed model will be ready to move on to the finishing touches much sooner than an SLA model.
Affordability
To truly compare the costs of SLA vs FDM, we have to look at both the initial investment, and the on going costs.
This is generally where FDM will take the lead over SLA, as both the printer itself, and the filament is much cheaper to purchase than the SLA equivelant.
Looking at the printers themselves, as seen in our best budget 3D printer guide, you can pick up a decent consumer FDM 3D printer for well under £200 / $200. This relatively affordable initial cost is one of the reasons why FDM 3D printing has become so popular.
In comparison, the cheapest consumer SLA 3D printers are more expensive. Although they have started to drop in price rapidly recently. It wasn’t overly long ago that the cheapest SLA machine cost well over £2000. But now you can find models such as the AnyCubic Photon for around £300 / $300.
Moving on to the print materials. Rolls of ABS or PLA filament are relatively cheap, with prices as low as £15 per kg. In comparison, a litre of resin will cost you over £40 depending on the brand.
Winner – FDM
Both of these factors lead me to look at the FDM 3D printer as the cheaper option to purchase and run over time. While it does come with drawbacks compared to SLA 3D printers, you can’t argue that it’s certainly cheaper to run!
Strength
Like many of the categories above, there are a huge amount of variables when we look at the overall strength. These can be the material used, the print density and infill amount just to name a few.
Typically FDM prints will use a percentage of infill, meaning they aren’t fully solid inside. Printing with 100% infill is very time consuming and very rarely required. The amount that you infill will determine the overall rigidity of your FDM print.
But also, there is the issue which I mentioned above of the FDM layers. When printing on an FDM 3D printer the layers are melted on top of one another. This can allow pockets of air or other artifacts between each layer, meaning you wont have 100% adhesion between layers. This can result to some instability on the Z axis with FDM prints.
SLA on the other hand doesn’t suffer from this problem of artifacts, as SLA prints when done correctly can be 100% air tight. This doesn’t mean that all SLA prints are stronger than FDM prints though.
Many consumer resins can be very brittle once cured. They aren’t designed to be strong, rather they’re designed to be affordable and produce a smooth and accurate model. With these resins which aren’t designed with strength in mind, brittleness can creep in making your model rather delicate to handle. More so than a PLA or ABS filament print.
Despite this, there are both filaments and resins which are designed to be more durable. And if you look to the top end, you will find resins which can outperform filament prints in the strength department. Although these can be costly, and are rarely needed within consumer printing.
Winner – FDM
Ultimately, on a consumer level, FDM prints will have more strength and durability than an SLA equivalent. This is mainly due to the less brittle and more durable nature of ABS and PLA over resin.
Which 3D Printing Method is Best? FDM vs SLA?
Deciding on which type of 3D printer is right for you is really dependant on your overall use. Both FDM and SLA have their own pros and cons, and both are orientated towards different applications.
If you are looking to prioritise the quality of finish and overall precision of your model, then SLA printing is right for you. If your overall budget is a factor, or you don’t fancy the longer process of resin printing then an FDM printer could well be better suited.
Situations where FDM 3D printing excels
- Low cost 3D printing
- Printing 3D models quickly
- Good entry point for beginners and hobbyists
Situations where SLA 3D printing should be used
- Priority on precision and quality of your model
- When your model isn’t designed to be strong or handled
