Stereolithography (SLA) (SL)
Overview: SLA provides the ability to print very tight tolerances, smooth surface finishes and high resolution of small features. The main downside is the lower mechanical strength and not suitable for exposure to UV or sunlight.
Materials Used & Part Characteristics: Photopolymer (UV curable) epoxy or acrylic-base materials are used to manufacture fine resolution cosmetic parts.
Where used: Cosmetic prototypes that require high resolution details and smooth surface finishes. Also used in molds for casting other materials.
The SLA Process
Watch the SLA Process
Manufacturing Process:• A UV curable photopolymer is poured or dispensed into a tank.
• A build platform is lowered into the tank where there is only a thin later of liquid resin between the build platform and the bottom of the tank.
• A UV laser is directed from the bottom of the tank to selectively cure the liquid resin to a hardened plastic.
• The part is built in consecutive layers. The standard resolution is .004” per layer and ultra fine resolution can reduce to .001” per layer.
• When the layer is complete the part is lifted from the bottom of the tank letting fresh resin flow beneath the part.
• The build platform is returned back into the tank to begin building the next layer.
• If there is an overhanging and unsupported geometry during the building process structure may need to be added to support the part as the final geometry is completed.
• Upon completion the part may be removed from the build platform.
Finishing: A bead blast finish provides a fine matte texture and fine resolution parts can be polished for gloss surfaces. Parts can be painted or clear coated for UV protection. Sanding may also be required on surfaces that required supports during the build process.
Tolerances: Ultra fine layers to .001”, Tolerances for all processes are approximates as size, geometry, wall thickness, and material selection will impact manufacturing tolerances.