Processes - Additive Manufacturing
Stereolithography (SLA)
Stereolithography (SLA) is the most widely used rapid prototyping technology. It can produce highly accurate and detailed polymer parts. It was the first rapid prototyping process, introduced in 1988 by 3D Systems, Inc., based on work by inventor Charles Hull. It uses a low-power, highly focused UV laser to trace out successive cross-sections of a three-dimensional object in a vat of liquid photosensitive polymer. As the laser traces the layer, the polymer solidifies and the excess areas are left as liquid. When a layer is completed, a leveling blade (may not appear in newer models) is moved across the surface to smooth it before depositing the next layer. The platform is lowered by a distance equal to the layer thickness (typically 0.003-0.002 in), and a subsequent layer is formed on top of the previously completed layers. This process of tracing and smoothing is repeated until the build is complete.
Once complete, the part is elevated above the vat and drained. Excess polymer is swabbed or rinsed away from the surfaces. In many cases, a final cure is given by placing the part in a UV oven. After the final cure, supports are cut off the part and surfaces are polished, sanded or otherwise finished.
Advantages
High Precision
Excellent dimensional accuracy and intricate detail making it suitable for prototypes, jewelry, dental models.
Smooth Surfaces
Looks good straight out of the printer and does not require further sanding to improve the surface finishing unlike FDM.
Complex Geometries
Capable of producing highly detailed and complex parts.
Aesthetic Quality
Ideal for presentation models and parts that need a store-ready look. It is suitable for producing high quality miniatures and models such as high-quality figurines, scale models, and collectibles.
Disadvantages
Cost
Often comes with a steeper price tag due to the higher material and processing costs associated with resin printing. In comparison, SLA resins can be more expensive than other 3D printing materials like filament used in FDM printers.
Build Size
Smaller build volumes could limit the size of individual parts. For jumbo projects, parts may need to be split and assembled post-printing. Many desktop SLA printers have relatively small build volumes, restricting the size of objects that can be printed in one piece.
Post-processing
You may need additional steps like support removal and UV curing to finish up the part, other than that cleaning is required after using it which can impact lead and labor time.
Brittleness
Resins can be less impact-resistant than FDM materials.
Capabilities
Disclaimer: All process specifications reflect the approximate range of a process's capabilities and should be viewed only as a guide. Actual capabilities are dependent upon the manufacturer, equipment, material, and part requirements.