FDM/FILAMENT PRINTING
Fused deposition modeling, or FDM for short, is a material extrusion method of additive manufacturing where materials are extruded through a nozzle and joined together to create 3D objects.
In particular, the “standard” FDM process distinguishes itself from other material extrusion techniques, such as concrete and food 3D printing, by using thermoplastics as feedstock materials, usually in the form of filaments or pellets.
A typical FDM 3D printer, therefore, takes a polymer-based filament and forces it through a heated nozzle, which melts the material and deposits it in 2D layers on the build platform. While still warm, these layers fuse with each other to eventually create a three-dimensional part.
Generally accepted as the simplest way to 3D print stuff, FDM is accessible, reasonably efficient, and widely popular. Expert FDM printing is notable for being remarkably more straightforward than resin 3D printing and massively cheaper than powder-based methods, such as selective laser sintering (SLS). For those seeking the best FDM 3D printing services, it’s a go-to choice due to its cost-effectiveness and ease of use. At JIM’S 3D PRINT SHOP, LLC, we also offer professional FDM and resin printing to meet diverse needs.
Broadly speaking, the extrusion and deposition system can be split into two main assemblies: the “cold end” and the “hot end”. The thermoplastics used in FDM 3Dprinting often come in filament spools, and the cold end is responsible for feeding this material from the spool into the 3D printer. Like such, the cold end also controls the rate at which material is being deposited on the other end, often referred to as “flow”.
The hot end, on the other hand, is responsible for heating the moving plastic material to the point that it’s adequate for being “purged” through a nozzle, hence its name. This step involves different components, including heating cartridges, heatsinks, and of course, nozzles.
The cold and hot ends must work synergistically to extrude just the right amount of material at the required temperature and physical state for properly stacking up layers.
Scalability is one of the most significant advantages of FDM 3D printing. Unlike resin 3D printers, FDM printers can be easily scaled to any size because the only constraint is the movement of each gantry.
One of the more obvious benefits of having an easily scalable design is the cost-to- size ratio. Due to low part costs and the simple designs involved, FDM printers are continually being made bigger and less expensive.
Speaking of cost, regular FDM filaments are by far the cheapest 3D printing material, especially when compared to other 3D printing methods, such as resin-based printing.
Another advantage regarding materials is flexibility. On any FDM printer, a wide variety of thermoplastic materials and exotic filaments can be printed with relatively few upgrades and modifications, and this cannot be said of other styles where the material must be, for example, a resin.
Finally, the overall experience with FDM printing is more straightforward than resin- based printing. With FDM, there’s no extra cleaning step other than (sometimes) removing supports, as opposed to the mandatory washing and rinsing, support removal, and curing for resin prints.
With FDM, once the printing process is done, the parts are ready to go, with post-processing steps being dependent on the material, printing characteristics, and intended use. Given the versatility of FDM 3D printing, models can pop off the print bed in multiple colors, whereas other productions, like resin prints, will necessitate painting.
FDM 3D printing, however, is not without its shortcomings. Due to the simplicity and overall cost of its components, FDM printers often require a lot of tweaking and adjusting (namely bed leveling) to reach the level of reliability and quality of other printing methods.
In contrast to resin, FDM relies heavily on physical movement. Because of this, in addition to calibration, many FDM printer components require regular maintenance and attention: belt tension, extruder cleaning, rail lubrication, and even part replacement like hot end nozzles.
Lastly, FDM printing is highly dependent on feedstock material quality. Poor dimensional accuracy in a filament can lead to several extrusion issues, and the chemical composition of the plastics can also make the printing process problematic. In addition, filament spools must be stored appropriately to avoid humidity exposure– which also affects the printing process.
This is a hot topic, as many consider print quality the Achilles heel of FDM 3D printing. While this claim is not unfounded, there are different perspectives to be considered here.
Print quality is not only about the look. The mechanical performance also counts here, and FDM offers a great value for producing strong and durable functional parts, especially when compared to fragile resin 3D prints.
FDM 3D printing is also very versatile because the print quality can be sacrificed in favor of speed and even sturdiness, making it an excellent tool for producing both pleasing aesthetic parts and more functional, tough ones.
Having said that, with proper calibration and slicer setting adjustments, FDM 3D printers can achieve a level of print quality that’s amazing considering the cost of the machine and the filament, even when compared to some resin 3D printers. And given the continuous development and open-source nature of the field, with upgrades like input shaping from Klipper or Marlin firmware, aesthetics won’t necessarily be affected by higher speeds.
Though already mentioned, the flexibility and availability of different FDM materials also play an important role here. A single FDM 3D printer can produce parts with entirely different properties and appearances just by changing the type of filament.
Still, if overall aesthetics and surface finish quality is required, FDM can be troublesome. Since the material is extruded in layers with a specific predefined thickness, detailed prints are hard to achieve and often require post-processing to acquire a professional, finished look. Depending on the material, what’s needed might be straightforward sanding or a more involved process, like vapor smoothing.
Small-scale parts are sometimes impossible to be printed with FDM, too. Since the standard nozzle size is 0.4 mm, any finer detail would require a nozzle replacement (down to 0.2 mm), and even so, it simply can’t beat the precision and crispness of resin-based 3D printing.
Another downside of FDM printing is that they create an inherent weak point in the print where each layer is joined. One can argue that this is true for any 3D printing process. While that’s true, this condition is worse for FDM 3D printing, as the bonding strength between layers is lower.
We’ve mentioned the feedstock material for FDM 3D printing, which is known by many simply as filament. And that’s precisely what it is: a long strand of polymer-based material rolled up in a spool.
By convention, the diameter of the filament strand is either 1.75 or 2.85 mm, and that’s dependent on the extrusion assembly of the 3D printer. It’s worth noting that a1.75-mm extruder will only take this filament size.
The most common filaments for FDM are PLA, PETG, and ABS – in this order. PLA is perhaps the easiest material to 3D print with FDM, and it’s also biodegradable and odor-free. Its downside is its low heat resistance, softening with temperatures as low as 60 °C.
PETG, on the other hand, offers much better temperature resistance but can be a bit more troublesome to 3D print, as it’s very prone to oozing and stringing. ABS takes the lead in mechanical properties, although it can be tough to 3D print without a printer enclosure. ABS is known to release toxic fumes during the printing process, which is also why an enclosure is needed.
With all that said, the experience with each of these materials may differ with each user, equipment, and especially with the filament manufacturer.
As mentioned, one big advantage of FDM 3D printing is the flexibility of materials, colors, and their availability in the market. There’s a massive availability of exotic and odd materials, such as metallic-infused filaments, carbon-fiber plastics, glow-in-the-dark materials, and even rubber-like thermoplastics like TPU.
I use the Prusa Research MK3S+ printers with a print capacity of 25×21×21 cm (9.84″×8.3″×8.3″) (HWD)
