FDR vs. SLA: The Right Polymer Manufacturing Choice for Your Application

The additive manufacturing (AM) industry has no shortage of acronyms when it comes to the various methodologies of industrial 3D printing. In polymer 3D printing, there are three main methods of plastic 3D printing, here is a short overview:

Fused Deposition Modeling (FDM) is a material extrusion method of AM where a polymer-based filament is drawn down a heated nozzle and melted along 2D layers of a build platform. While it remains heated and begins to cool, the layers fuse together to create a three-dimensional part.

Stereolithography (SLA) uses a low-powered laser to harden liquid resin that is contained in a reservoir, commonly called a vat to create a desired 3D shape. The process converts photosensitive liquid plastic into solid plastic in a layer-by-layer procedure called photopolymerization.

Selective Laser Sintering (SLS) is a laser powder bed fusion (LPBF) process that uses a high-powered laser to selectively fuse powdered materials layer by layer to create a three-dimensional object. The process begins with a thin layer of powder being evenly spread across the platform, where a laser selectively sinters the powder and melts the first layer of the object being fabricated.

What is FDR and why compare it to SLA?

Fine Detail Resolution (FDR) is an industrial 3D printing technology that uses an advanced CO-laser to achieve unprecedentedly small filigree structures. Using FDR, you can build durable parts with the high level of detail resolution typically associated with SLA, at the industrial production volume and pace of SLS.

Key features of FDR

FDR is capable of part production volume comparable to traditional SLS systems because the technologies are very similar; both are forms of LPBF. But FDR utilizes CO lasers that generate ultra-thin beams with a 0.22 mm (200 µm) focus diameter — about half the size of what’s seen in SLS 3D printers. The ultra-fine laser allows for powder melting and shaping at the granular level necessary to create tiny part details: for example, detailed surface lettering and intricately shaped connectors on a microelectronic plug.

Meanwhile, fast but even powder application from the recoater ensures material densification, further contributing to part accuracy. Ultimately, depending on part geometry, FDR’s margin of error for dimensional accuracy is just +/- 40µm, which matches injection molding. The precision FDR brings to part builds also comes with stability, robustness and durability — ideal for electrical and electronics equipment, special mechanical engineering and medical device manufacturing.

Meanwhile, non-LPBF AM methods like SLA and digital light processing (DLP) — another polymer resin-based process — can produce similarly high-resolution results. But SLA and DLP parts function most effectively as proofs of concept or for experimental use. If production were scaled up to a volume necessary for industrial-level AM, the detail resolution and dimensional accuracy of SLA and DLP would not be as reliably high.

Comparing the benefits of FDR and SLA

1. Detail and dimensional accuracy

SLA: In the past, SLS 3D printing has not been able to achieve the levels of detail and dimensional accuracy of SLA technology. SLA has long held the strongest capability in polymer 3D printing of detail and dimensional accuracy, but now has a strong competitor in FDR technology.

FDR: The chief advantage of FDR is built into its full name. Alongside FDR’s high resolution and impressive surface finishes, it boasts outstanding dimensional accuracy (+/- 40µm), so the technology also improves the odds of parts in a job coming out right the first time.

2. Supportless building

SLA: Various non-LPBF polymer 3D printing methods typically require support structures. In general, the entire part must be attached to the build plate during the build process to ensure the part stays in its intended place. Any necessary support structures must be accounted for during design, printed during the build and carefully removed afterward. This slows down production, post-processing and the overall AM process chain.

FDR: Like SLS — FDR doesn’t require supports during part builds. The unfused powder particles are sufficient to hold the parts in place and support overhangs. This simplifies the design, eases placing of parts within the build volume, helps speed up post-processing and reduces material waste.

3. Higher productivity

SLA: Although SLA can match FDR in the fine detail capability comparison, it cannot approximate its production volume. This is due in large part to the slow build processes of the resin-based method, which the relatively quick laser sintering of FDR can easily outpace.

FDR: Along with the fast-paced production advantage of SLS, FDR also allows you to nest parts in multiple vertical levels (depending on part height) to take full advantage of the process chamber’s height — not only its length and width. This contributes further to increased productivity.

4. Simplified post-processing

SLA: When the printing process is completed, individual parts must be delicately set aside for post-processing. Also, further exposure to laser energy or UV light is often required to harden parts produced via these methods, even those that will only be prototypes.

FDR: By contrast, FDR requires minimal post-processing: No UV or heat treatment is necessary, and there are no supports that must be removed.

5. Strong mechanical properties and stability

SLA: SLA parts can be quite accurate, but the polymer resins featured in these processes are sensitive to UV light. As such, parts must be kept away from sunlight or any other source of light that contains UV radiation.

FDR: The polymer used for FDR, polyamide 11 (PA 11), has high impact resistance, high elongation at break and more. This ensures that FDR components can easily stand up to tough operating environments and be utilized as end-use parts. By contrast, the PA 11 used for FDR is strongly resistant to UV rays while being both chemically and mechanically heat-resistant. This helps strengthen the effectiveness and lengthen the life cycle of FDR-produced parts.

6. Sustainable and responsible material use

SLA: The photopolymer resins in SLA and DLP are toxic and require careful disposal procedures. During production, the resins produce unpleasant fumes and require you to wear gloves when handling them.

FDR: PA 11, the material used in FDR 3D printing, is made entirely from castor beans, which grow on marginal lands not suitable for food crops, and can be recycled. Also, while you wouldn’t want to eat castor beans, the PA 11 made from them is biocompatible, making it useful for the medical field as well as products that come in contact with food.

Interested in learning more about FDR technology and its capabilities? Watch the EOS on-demand FDR webinar today by registering here.