Different Types of 3D Printers – FDM vs. SLA

There are two main types of 3D printers, both utilizing additive manufacturing technology to create a new object from a base material. The first type, called Fused Deposition Modeling (FDM), uses a heated metal block to melt a strand of the base thermoplastic material, called filament, which is extruded through a small nozzle which applies the material to the buildplate to build the new object one layer at a time from the bottom up. Typically the printhead moves around the buildplate in the X- and Y-axis, and the buildplate moves up and down in the Z-axis as additional layers are applied, however some printers use a buildplate which moves in the Y-axis and some the printhead moves in the Z-axis. The other type of 3D printer, called Stereolithography Apparatus (SLA) uses a laser or a projector to harden a liquid resin through the process of UV curing. In these printers the build platform hangs down into a vat of liquid resin and the resin is cured against the platform by UV light from a laser or projector. As the platform rises the object grows in height, being built from the top down. Now that you know a bit about the two primary types of 3D printers, let’s examine the pros and cons of each technology.

FDM Printing
Pros:
Safer than SLA printers – FDM printers use a spool of solid thermoplastic as the base material which is melted then applied to a buildplate. While some materials may give off some noxious odors they are generally relatively harmless. SLA printers use a UV curable liquid resin which is highly toxic in its liquid state.
Produces stronger parts: FDM printers can be used to create parts that will be exposed to mechanical stress. This allows production parts to be produced and fitted quickly. Generally FDM printing materials have been reported to be 3-20 times stronger than the same part printed with SLA technology.
Wider variety of materials and colors: FDM printers can be adjusted to operate at different temperatures which allows the use of different materials including PLA, ABS, PETG, Nylon, Polycarbonate and more. Many of these materials are available in countless colors and shades from a number of manufacturers, unlike SLA printers which require a specific type of resin available in very limited colors.
Cons:
Less detail in prints: FDM printers typically use a nozzle between 0.2mm and 1mm, meaning the line of extruded plastic is at a minimum 0.2mm wide and the smallest structure that can be reproduced is 0.2mm with a 0.2mm nozzle. Most SLA printers are able to create much smaller structures, curing resin in a point as small as 0.01mm allowing for much greater accuracy and precision than is available in FDM printing.

SLA Printing
Pros:
Higher resolution than FDM: SLA Printers use a small laser or a projected image to cure the liquid resin into the solid model. Because the point of light is much smaller than the hole in a FDM nozzle SLA printers are able to produce a higher resolution item.
Less calibration required: SLA Printers use a targeted beam of light from a laser or projector and only require movement in the Z-axis, whereas FDM printers require the printhead to be moved around the build volume. Because FDM printers move in all three axis the movement must be precisely calibrated in order to ensure the melted thermoplastic is applied to the buildplate in the correct location.
Cons:
More expensive to operate: SLA Printers require a number of consumable components whereas FDM printers consume only one component, the filament. SLA Printers require liquid resin, high-strength ethanol for post processing, as well as replacement of the resin vat or film on which parts are printed.

Danger: SLA printers use a UV curable liquid resin. Once cured this resin is completely harmless, however in its liquid state it is highly toxic to humans. In order to work safely with SLA printers one must wear protective gloves at all times in order to avoid contact with the uncured resin.

In conclusion, both types of 3D printing technology have their benefits and their downsides. By utilizing both FDM and SLA technologies Access 3D Services is able to utilize the most appropriate technology for the individual needs of each customer. Whether our customers require an extremely high detail prototype or a strong, mechanical part Access 3D Services is able to meet all of their needs.

Article by Joe Eckert, Operations Director, Access 3D Services

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