Stereolithography (SLA) 3D Printing

This technology is ideal for high-resolution finishes regarding medium- to large-sized parts. It is an extremely cost-effective solution for creating durable, aesthetically pleasing parts of considerable size on a tight deadline. SLA resins with extremely high heat deflection are available and are great candidates for molds or inserts.

How does the stereolithography technology work? SLA cures photopolymer resin with an ultraviolet laser. The laser traces a shape dictated by the original file across the surface of the resin bath. The resin touched by the laser hardens, then the build platform descends in the resin bath and the process is repeated until the entire part is complete.

SLA 3D Printed Parts and Images

*Parts over 250mm in any dimension require quote review.

Depending on the material chosen, SLA parts can have high impact strength, high temperature performance, water resistance, and stiffness and rigidity.

SLA Finishes

We offer several finishing options for your SLA parts–please inquire about the finishing you would like to achieve with a Fathom expert. Our finishing services provide you with a one-stop-shop for all your prototype and production needs, including painting, texturing, engraving and plating.

Our SLA Finishing Levels Include:

• Strip and Ship – Supports are removed and minimally sanded in order to remove the support nubs left behind with some nubs remaining in hard to reach areas. Build lines are visually present and the parts have a granulated/gritty texture.
• Sanded and Bead Blasted – Supports are removed and then the parts are bead blasted and sanded smooth. Build lines are somewhat present, but parts have a smooth texture. Bead blasted parts will make clear parts look frosty/cloudy.
• Rapid Paint – Supports are removed, and then the parts are sanded and bead blasted. Paint is applied directly to parts without primer which means the build lines will be somewhat present through the paint.
• Rapid Clear – Supports are removed and then the parts are sanded and bead blasted. Basic clear coat is applied to parts, but the build lines will still be somewhat present under the clear coat.
• Show Quality Paint – Supports are removed, and then parts bead blasted and extensively sanded until all build lines are removed. Primer is applied before painting. Pantone color or color chip will need to be supplied to match color. Parts are smooth and build lines are completely removed. Parts look as close to production quality as possible.
• Optically Clear – Supports are removed, and then parts bead blasted and extensively sanded until all build lines are removed. Multiple coats of clear are applied. Parts are smooth and build lines are completely removed. Parts are completely clear–almost glass like.

Applications of SLA 3D Printing

Fathom supports businesses across multiple industries to innovate and meet their goals using stereolithography technology. Some applications of SLA include:

• Medical technology
• Educational research
• Dentistry
• Engineering and product design
• Manufacturing
• Prototyping

What is the Difference Between SLA and SLS?

Stereolithography (SLA) is a 3D printing method that uses both a UV laser and a resin that can be cured by UV light. A single laser is directed to specific areas to cure the resin and create a solid pattern. SLA is popular because it can print parts with greater precision than traditional fuse deposition modeling (FDM) machines.

Selective Laser Sintering (SLS) is another 3D printing process that uses a laser to melt, sinter, or fuse together particles, which result in a 3D part. SLS printers are commonly used for plastic, metal and ceramics. These materials are usually in powdered form. SLS does not require support as the unsintered powder around the part provides support. SLS has a broader range of materials available.

There are a number of differences between SLA and SLS. Selective laser sintering machines use a very powerful laser and as such, they are entirely encased, blocking the view of the part as it is printed. SLA machines are typically enclosed in tinted glass or plastic, which allows the operator to view the part as it is built.  SLS does not use toxic resins and the powdered material is considered easier to work with. Objects made by SLA machines are complex and detailed but can be brittle. SLS parts are not as detailed, but still complex and are considered suitable for mechanical use.

Fused Deposition Modeling (FDM) vs. Stereolithography (SLA)

FDM deposits thermoplastic filament through a hot extruder, layering the material in the print area, resulting in a 3D part. Stereolithography also builds parts layer by layer but utilizes a laser and resin instead. In FDM, the part’s smoothness and precision largely depend on the extruder’s movements and nozzle size. SLA is capable of producing accurate and smooth parts. This is because the laser used does not press as much force on the workpiece. The ability to make parts with finer details is why SLA may be preferred for specific projects. There are also differences in post processing. FDM parts may need to be sanded to achieve a smoother surface. SLA parts have a sticky residue after being removed from the machine and must be washed in a bath of isopropyl alcohol. FDM is considered the right choice when precision is not essential and for rapid prototyping. Stereolithography is useful for projects requiring intricacy and smooth surfaces, and when strength and durability are not critical. SLA is also an excellent choice for creating molds for casting.

Stereolithography Questions Answered

Q: What finishes are offered using SLA?

A: Please refer to our list of finishes above.

Q: Can SLA models be machined?

A: Yes, SLA parts can be milled, drilled, tapped, or lathed.

Q: What geometries are best suited for stereolithography?

A: SLA can be used for small and large parts. These parts may have tight dimensional tolerances and require smoother finishes, which are all possible with SLA.

Q: Is stereolithography a faster process than fused deposition modeling?

A: SLA is slower than FDM because the SLA printer’s laser has a smaller surface area and takes more time to complete each layer. In FDM, the printer can print thicker layers, which results in a reduction of time.

History of Stereolithography

Here is a summary of the history of stereolithography:

• 1970s: Dr. Hideo Kodama created the layered approach to stereolithography and used ultraviolet light to cure photosensitive polymers.
• 1986: Charles W. Hull patented stereolithography and founded 3D Systems, which commercialized stereolithography.
• 2000s: Desktop 3D printers using fused deposition modeling are introduced.
• 2011: Desktop 3D printers using stereolithography are launched.

Why Choose SLA 3D Printing?

Brands use SLA for many reasons. SLA is an excellent choice if your project requires fine features, smooth surface finishing, part precision and accuracy, isotropy, mechanical attributes, water tightness or versatility of materials.

There are many advantages to stereolithography, including:

• Fine features
• Smooth finish
• Accuracy
• Material versatility
• Design freedom
• Water tightness
• Isotropy
• Faster turnaround time
• Quick design changes
• Budget-friendly
• Scalable

SLA offers a combination of high-quality resolution and surface finish at large volumes. SLA is also very effective at faithfully capturing the intricacies of even the most complex parts. Clear SLA resins can achieve colorless clarity with additional post processing to mimic clear plastics. Consistently used for trade show models, aesthetic parts and snap fits/functional assemblies, SLA specializes in creating parts that are highly cost-intensive to produce using any other method of manufacturing.