The History of Stereolithography (SLA)January 14, 2014
Within the field of rapid prototyping there are a variety of ways in which to create a product. From Fused Deposition Modeling (FDM), to Selective Laser Sintering (SLS), to Casting, there are options when it comes to producing a 3D rapid prototyped product from scratch. We provide three types of rapid prototype printing, which are FDM, Polyjet, and Stereolithography (SLA). In this article we want to look at the history of the SLA method of rapid prototyping as well as its pros and cons.
On March 11, 1986, a man by the name of Charles (Chuck) W. Hull patented the method of stereolithography. He also coined the name in his U.S. Patent 4,575,330, entitled “Apparatus for Production of Three-Dimensional Objects by Stereolithography”. Chuck defined stereolithography as the method of making solid objects by successively laying down thin layers of ultraviolet curable material one layer at a time through the use of the apparatus.
In this patent an ultraviolet light was concentrated on specific areas of a vat filled with liquid photopolymer. Through the concentration of this UV light, which was controlled by a computer that was following the preloaded CAD file, it hardened the curable material one layer at a time. Once the UV light is focused on the space the photopolymer polymerizes/crosslinks and is changed in a solid.
It was in 1986 that Hall founded 3D System Inc. which was the first company to generalize dn commercialize this procedure.
How it Works:
Stereolothography is a form of additive manufacturing. As mentioned earlier, a UV light is concentrated on a particular area of a vat of photopolymer resin and the object is built one layer at a time.
The SLA is placed on a elevator that is controllable up to 0.05mm at a time. After the pattern is traced the SLA’s elevator lowers by one “level” in order to allow for another layer of resin to be laid. Once the stage is done, it happens all over again, re-coating the object with fresh material and joining the subsequent layers together.
Once each layer has been exposed to the UV light, the final design is immersed in a chemical bath in order to rid the design of excess resin. The design is alsu cured in a UV oven.
This form of additive manufacturing is particularly speedy, making it extremely beneficial. There are a variety of sizes that can be made as well, depending on the size of the SLA machine. These prototypes can form the master patterns for injection molding, thermoforming, blow molding and a variety of metal casting processes.
That concludes the history of stereolithography, as well as what we hope to be a variety of helpful bits of information about this unique form of rapid prototyping.