SLA and SLS 3D printing technologies differ in several key ways. SLA (stereolithography) is a process of using lasers to harden liquid resin, layer by layer. This results in highly detailed, precision parts with smooth surfaces and fine features. SLS (selective laser sintering) is a process that uses high powered lasers to fuse powdered materials together into solid objects. It produces strong parts with good dimensional accuracy, but the surface finish can be inconsistent due to its powder-based nature.
SLA and SLS are actually two very different technologies but are often compared when evaluating between a technology to pick for rapid prototyping. In this article, we breakdown the main differences between these two fantastic technologies and explore which could be a better fit for your project.
Stereolithography is known for its fine features, smooth surface finish, and pin point precision. While both SLA and SLS are great for building highly accurate to CAD models, when it comes to fine feature details, SLA can achieve much finer and intricate details through the use of its pin-point precision laser.
SLA is a mature 3D printing process that offers a variety of material options—transparent, high temperature, generic, rigid, and more. While SLS is more limited in terms of material selection, it uses engineering-grade plastics like Nylon with excellent mechanical properties superior to that of SLA resins.
The sintering process intrinsically creates a porous solid material, as the air that was originally within the powder goes to create microscopic air bubbles on the sintered material. Although this is nothing you can see with your naked eye, unlike SLA components, SLS parts feels slightly rough to touch. This means that a much greater post processing effort is needed to achieve certain surface textures and quality.
Industrial SLA printers can handle much larger builds (up to 800 x 800 x 550mm) than SLS printers (up to 400 x 400 x 450 mm). It also has the ability to maintain excellent detail and surface smoothness to a degree that cannot be achieved with selective laser sintering.
In terms of the size of a project, if you’re looking to print smaller size parts in larger quantities with speed, SLS 3D printing may be a better option. This is because parts can be strategically stacked in not just the x and y axis, but the z-axis as well. This allows for maximum usage of space and greater efficiency.
The cost difference between SLA and SLS can vary depending on material options, print time and amount of post processing needed. SLA typically have a lower average cost for quick prototypes with high visual standards. However, if you’re looking to prototype in materials with high mechanical properties, SLS may come out as the cheaper option.
| Industrial SLA | Industrial SLS | |
|---|---|---|
| Accuracy | ★★★★ | ★★★★ |
| Surface Finish | ★★★★ | ★☆☆☆ |
| Part Strength | ★☆☆☆ | ★★★★ |
| Speed | Offers excellent speed for high accuracy and fine detailed parts and prototypes | Offers excellent speed for high accuracy prototypes with excellent mechanical properties |
| Resolution | Offers excellent resolution | Less ideal for fine detailed features |
| Applications | High resolution and fine detail models Accurate to CAD parts Visual prototypes Good for prints with large builds | Functional rapid prototyping Accurate to CAD parts High strength prototypes Suitable for low volume end-use parts |
| Build Volume | Up to 800 x 800 x 550 mm | Up to 400 x 400 x 450 mm |
| Materials | Variety of resins including generic, rigid, high temp, high toughness and transparent resin options. | Nylon, glass fibre, TPU |
Find out which 3D printing technology is right for you
Certain considerations like strength, resolution, or part size may make the decision for you when deciding between SLA or SLS 3D printing. Refer to the table above when deciding between which process is better suited than the other based on key factors.
While the table provides a good overview, every project is treated on a case-by-case basis. If you’re having trouble picking between SLA and SLS, send us your 3D CAD file HERE, and our engineers will get back to you with advice.
