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An Overview
Stereolithography (SLA) builds a part in layers by exposing liquid photosensitive polymers to ultraviolet (UV) light that solidifies the liquid. The part is built upon a platform that is placed just below the surface of the liquid. A low-powered UV laser beam focused on the surface of the liquid, traces the first layer of the part and fills in solid areas resulting in the solidification of that layer on the platform. The platform is then lowered the depth of one layer, the solidified layer is re-coated with the liquid, and the laser traces the next layer of the part. The new layer adheres to the previous layer as solidification occurs. This process is repeated until all of the layers of the part have been solidified. The part is then removed from the liquid and any excess liquid is rinsed. Any supports are then broken off of the part and the part is cured in an UV oven called a Post-Curing Apparatus (PCA).
The liquids used for this technique are liquid epoxy and acrylate resin.
SLA parts tend to have very good feature detail.
A part constructed using this technology is not considered to be strong enough to replace production plastic parts, but can be used in a number of functional test applications. This technology requires supports for the part being built to attach the part to the platform, to prevent certain geometry from only deflecting due to gravity, and to also accurately hold the layers.
This technique was the first Rapid Prototyping (RP) technique and is often regarded as a benchmark upon which all other RP techniques compared.
Machines that perform this technology are referred to as Stereolithography Apparatus (SLA) and have been in existence since 1988.
Stereolithography was invented by Charles (Chuck) W. Hull. Hull coined the term in his U.S. Patent, entitled "Apparatus for Production of Three-Dimensional Objects by Stereolithography" issued on March 11, 1986. He also invented the STL file format commonly used today in the Rapid Prototyping process.
Disclaimer
DPT may not provide some of the services and/or techniques presented in the Knowledge Center. For a full list of services we do offer, please visit our rapid prototyping page.
