What is SLA 3D Printing?

When industrial manufacturers need aesthetic prototypes or non-functional end-use parts, they often hire a 3D printing service to build them using stereolithography, or SLA. Get to know more about SLA 3D printing, how it works, its advantages and disadvantages, and the wide range of materials and finishes it offers in this article.

What is SLA 3D printing?

Stereolithography (SLA) is the most common type of 3D printing services in use today. And for good reason: the resulting builds are highly detailed and aesthetic, while the process is cost-effective for low volume orders.

SLA 3d printed godart8001 material part

One of the reasons SLA has become so popular as a manufacturing method is because it’s versatile. It can print highly detailed and geometrically complex designs in a wide range of colors.

SLA is a method of 3D printing that is often used by industries such as automotive, consumer goods, medical, and jewelry to produce prototypes or non-functional end-use parts.

How does SLA 3D printing work?

SLA printers uses a UV laser to solidify, or cure, layer after layer of resin into the shape of an object. The object is built according to a design that has been pre-programmed into a computer.

During SLA 3D printing with certain materials, such as transparent resin, the object is reinforced with support structures to help it achieve and maintain a certain shape. In post processing, when the part has cooled, the support structures are removed.

SLA 3D printing material options

When it comes to range of materials, the SLA process is much more versatile than other 3D printing methods, like selective laser sintering (SLS).

Material	Characteristics
Generic Resin	Excellent surface quality Easy to shape accurately Moderate mechanical strength
Transparent Resin	Clear appearance Can be polished to achieve greater clarity Low mechanical strength
High Toughness Resin	Stable ABS-like or PP-like mechanical properties Becomes brittle and loses flexibility due to UV light
High Temp Resin	High thermal resistance Brittle Ideal for mold prototyping, casting and thermoforming tooling
Rigid Resin	High stiffness Resistant to deformation over time

SLA vs DLP

SLA 3D printing is often compared to digital light processing (DLP) 3D printing. Both use the same types of material – resin – and they are comparable to one another in resolution, precision, and surface finish. But they operate quite differently when it comes to how they cure the resin.

While SLA printers use UV lasers to “draw” the cross section of the 3D print on the layer of liquid resin, thus curing it, DLP printers use projectors to cure the entire cross section at one time.

Thanks to its laser-drawing curing method, SLA is better than DLP for producing large batches of parts at a fast rate. The projectors in DLP printers simply can’t cover as many objects at the same time as the lasers in SLA printers.

Designing parts for SLA

SLA parts are brittle and prone to curling. To ensure better part quality and a successfully print, it is important to design according to a set of recommendations. Find out how to design walls, mating parts, pins, overhangs and more, in our SLA 3D Printing Design Guide.

Advantages of SLA

High Dimensional Accuracy: SLA is capable of producing high dimensional accuracy, making them a great choice for printing intricate details.
Smooth Surface Finish: SLA 3D-printed parts come out smooth, which is why stereolithography is perfect for building aesthetic prototypes.
Material Versatility: When it comes to range of materials, the SLA process is much more versatile than other 3D printing methods, like SLS.
Prints Small and Large With High Precision: Whether the part or prototype you want to produce is small or large, you can still achieve the same high precision results using SLA 3D printing.

Disadvantages of SLA

Support Structures Are Always Required: SLA prints require support structures to maintain their shapes. These must be removed in post processing, adding an extra step.
Brittle Parts: Stereolithography parts come out brittle and easy to break. This fact makes the process less than ideal for functional prototypes.
Degradation Over Time: SLA 3D printing is photosensitive, so the parts will degrade over time when exposed to sunlight for prolong periods of time.
Liable to Curling: SLA parts are liable to curling during the printing process.

Uses of SLA

Due to its ability to produce high precision prints with fine details, SLA is most useful for manufacturing prototypes and models for all types of industries. For example, it can be used in the medical industry to produce models of human body parts, or even limited functional parts like dental retainers.

Stereolithography has other, more entertainment-based applications, as well. For example, it is an excellent method of producing action figures or game pieces.