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stereo lithography commonly referred to as SLA, and selective laser centering, or SLS.

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SLA uses a UV laser or projected light source to selectively cure a liquid resin,

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forming parts layer by layer with very high precision.

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Desktop SLA printers typically build parts upside down,

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pulling them out of a shallow resin vat as each layer is cured.

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SLS works by using a laser to selectively center powdered material,

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typically nylon, fusing particles together layer by layer to form a solid part.

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After each layer, a fresh coat of powder is spread on top, and the process repeats.

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SLA offers a wide variety of materials,

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each prioritizing different properties like dimensional accuracy, optical clarity, and more.

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Though SLS also has a variety of materials, as a relatively more industrial process,

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SLS powders typically focus more on mechanical properties like durability, stiffness, and toughness.

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Both processes are capable of printing elastic parts.

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Most SLA parts require support structures to combat warping or print failure,

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which have to be removed by hand.

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For SLS, as parts are made in a bit of powder,

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any unused loose powder acts as support for the next layer, so no supports are needed.

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Part orientation can be virtually arbitrary, and parts can also stack on top of each other in the build chamber.

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SLA generally produces better surface finish and finer details than SLS,

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allowing smooth surfaces and minimum feature sizes around 0.1 mm.

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SLS, which fuses powdered thermoplastics, can achieve good dimensional accuracy and strong functional parts,

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but its surfaces are naturally rougher due to the powder particles.

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The surface feels grainy to the touch and fine details below 0.3 mm may be difficult to reproduce.

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Both processes create near-isotropic parts with good mechanical properties,

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but there are differences as well.

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In general, SLA parts are usually more brittle and may be prone to cracking,

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especially after prolonged use, whereas SLS parts tend to be more durable and robust.

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SLA parts need a solvent wash to remove excess resin,

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post-curing through UV or heat to reach full strength, and manual support removal.

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This all needs to be done with proper protection,

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as the uncured resins are hazardous to touch.

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SLS parts need to first cool down, as the thermal shock from early removal can lead to parts warping.

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Then, the excess powder must be removed to reveal the produced parts.

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Sand or bead blasting is often used to remove any remaining powder and improve surface finish,

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though it is optional.

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As the powder used for SLS is very fine,

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it can be harmful to inhale and protection or containment is needed.

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A SLA printer is usually cheaper with some desktop models available,

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and although household SLS machines do exist now,

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most are more expensive and orientated for industrial use.

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In terms of operation, SLS can be slightly cheaper than SLA,

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due to efficient material use and less consumables needed, though this may vary by use.

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SLA excels at producing highly detailed, smooth and visually precise parts,

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making it ideal for jewelry, dental models, figurines, and aesthetic prototypes.

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SLS produces strong, durable, and stable components with good dimensional accuracy,

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suitable for functional prototypes, end-use parts, jigs, fixtures, and complex assemblies.

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Thank you for watching!

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To learn more about these two manufacturing processes, check out the CustomPartNet website.