About SLA 3D printing

What is SLA 3D printing ?

Many industrial 3D printing processes exist today (FDM, SLA, SLM and SLS), and one of them is SLA 3D printing (stereolithography).

SLA is an additive manufacturing process that is a liquid polymers polymerization  technology. In SLA 3D printing, a UV laser selectively cures a polymer resin of a polymer liquid together layer by layer. The material used in SLA is a photosensitive thermoset polymer.

Contrary to SLS, SLA has the part printed from the bottom of the bin of liquid polymer layer by layer whereas the SLS has the part printed from the top of the bin of powder of polymer layer by layer. Other difference, SLS material is powder of polymer, SLA material is liquid of polymer.

How does SLA work ?

1.      Bin of liquid polymer and the platform are located above the UV laser system.

2.     The UV laser creates the layer by selectively curing and solidifying the liquid resin. The UV laser activate the monomer carbon chains in the liquid of polymer.

3.     After printing, the printed part is not fully cured, it requires further processing under UV light to meet mechanical and thermal requirements.

4.     When a layer is complete, the process repeats until the part is completely printed.

Unlike SLS, SLA 3D printing need support structure in the same material as the printed part, then removed manually after printing. It produces parts with variable mechanical properties that need to be post processed to achieve better mechanical properties.

One of the biggest problems of SLA is curling of the parts, need to avoid large thin and flat areas.

Advantages:

1.      SLA parts have a smooth surface finishing, ideal for aesthetic prototypes.

2.     Good for manufacturing small parts.

Disadvantages:

1.      SLA parts are more brittle so not suitable for functional prototypes.

2.     The mechanical properties and visual appearance will degrade over time.

3.     Support structures are required and need to be removed manually.

4.     Need to post process by UV light to achieve better mechanical properties