Stereolithography (SLA)

UV curing resin.

What is Stereolithography?

Stereolithography (SLA) is a form of additive manufacturing that uses UV light to cure UV sensitive resin. Stereolithography is similar to fused deposition modelling as it relies on building successive layers on top of one another. A UV light is directed to a location on a build plate submerged in resin causing it to solidify. This process is repeated over and over again to slowly develop the part.

3D Printed SLA Mould
3D Printed SLA Mould

3D Printed SLA injection mould for silicone and expoxy.

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SLA 3D Print Cured
SLA 3D Print Cured

A cured test bench showing the level of detail in a SLA 3D print.

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SLA 3D Print Fine Detail
SLA 3D Print Fine Detail

SLA 3D Print showing fine detail possible due to accuracy and precision of the stereolithography process.

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3D Printed SLA Mould
3D Printed SLA Mould

3D Printed SLA injection mould for silicone and expoxy.

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The main distinguishing factor between the SLA and FDM is the resolution and layer height that can be achieved. The layer height of SLA printers is generally 0.025mm to 0.1mm, significantly smaller than FDM. With a resolution of around 0.5 um the final product appears almost completely smooth. This precision allows for small parts to be produced with ease.

Fused Deposition Model Layer Lines
Fused Deposition Model Layer Lines

Layer lines of a FDM 3D print showing the effects on a final part.

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SLA Layer Lines: Cured
SLA Layer Lines: Cured

Smoothed layer lines on a cured SLA print.

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SLA Layer Lines: Uncured
SLA Layer Lines: Uncured

Layer lines from a SLA print that has not been cured.

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Fused Deposition Model Layer Lines
Fused Deposition Model Layer Lines

Layer lines of a FDM 3D print showing the effects on a final part.

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When to use Stereolithography

Stereolithography is usually reserved for small or highly detailed parts as each additional layer results in significant increases in manufacturing time. Typically most larger parts can be handled by FDM processes. There are cases however when SLA may be necessary on larger parts.

SLA like FDM is suitable for small runs and prototyping. Especially when the component has complex geometry that cannot be produced with subtractive manufacturing.

If you need help selecting the right process to manufacture your part please contact us.

Materials

SLA is restricted to UV sensitive resins. Despite the restriction there are still a number of colours available to choose from.