SLS vs SLA: when to choose powder or resin

SLS and SLA offer different design options. We select by part, material, surface and required checks. Both processes are in the workshop; a functional model may need powder or a suitably selected resin.

Supports and cleaning

Unsintered powder supports SLS parts. SLA supports and orientation are planned around surfaces and washing. Powder also has to leave internal spaces; resin has to be washed and post-cured to its material requirements. A channel is not cost-free just because it can be drawn in CAD.

When to consider SLA

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  A transparent Clear Resin V5 model: agree the visible surface and finishing.
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  A larger model: PA12 has a 159.8 × 159.8 × 295.5 mm part limit; Form 4L has a 353 × 196 × 350 mm build volume. Supports and orientation also use space.
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  A model for painting or a silicone mould: identify surfaces where support marks matter.
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  Fine details: select the resin and profile. Layer height alone is not a dimensional tolerance.

When to consider SLS

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  A complex shape that is difficult to support separately, with access for powder removal.
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  An integrated mechanism with designed gaps and motion that can be checked after cleaning.
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  A series packed throughout the chamber volume. Compare pricing for the actual model and finishing.
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  A functional part in selected PA12, PA11 or TPU 90A. The material sheet and operating conditions remain the basis for evaluation.

Why does the calculator price powder, while resin is priced by a human

The automatic PA12 result is indicative. For SLA, a technologist checks resin, height in the chosen orientation, parts per platform, supports and finishing. Send the model through the quote page with SLA selected or the resin enquiry form. Fitting a bounding box into Form 4L does not confirm a supported print layout.

How to resolve this on your own file

Specify quantity, function, force, temperature, environment, fits and visible surfaces. Resin properties refer to the post-cured state in its TDS; specimen results do not establish part service life. See SLA printing, powder data sheets, Tough 2000 Resin V2 and design rules. Send a model or a brief without a file.

Sources: Fuse Series SLS Design Guide, Formlabs Form 4L.