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An SLA produced part
An example of a complex SLA 3D printed electronic circuit board PCB with various components to simulate the final product.
Felix 3D Printer[1]

Stereolithography (SLA or SL; also known as Optical Fabrication, Photo-Solidification, Solid Free-Form Fabrication, Solid Imaging, Rapid Prototyping, Resin Printing, and 3D printing) is a form of additive manufacturing technology used for creating models, prototypes, patterns, and production parts in a layer by layer fashion using photopolymerization.[2]


3D printing was first known as Rapid Prototyping and was invented with the intent of allowing engineers to create prototypes of their designs in a more time effective manner.[3][4] The technology first appeared as early as the 1970's and it was Japanese researcher, Dr. Hideo Kodama who first invented the modern layered approach to stereolithography using ultraviolet light to cure photosensitive polymers.[4] The term “stereolithography” was coined in 1986 by Charles (Chuck) W. Hull.[2] Chuck Hull patented stereolithography as a method of creating 3D objects by successively "printing" thin layers of an object using a medium curable by ultraviolet light, starting from the bottom layer to the top layer. Hull's patent described a concentrated beam of ultraviolet light focused onto the surface of a vat filled with a liquid photometer. The UV light beam is focused onto the surface of the liquid photopolymer, creating each layer of the desired 3D object by means of crosslinking (or degrading a polymer). In 1986, Hull founded the world's first 3D printing company, 3D Systems Inc,[5][6][7] which is currently based in Rock Hill, SC. Stereolithography's success in the automotive industry allowed 3D printing to achieve industry status and the technology continues to find innovation uses in countless fields of study.[3][8] Attempts have been made to construct mathematical models of stereolithography processes and to design algorithms to determine whether a proposed object may be constructed using 3D printing.[9]


Stereolithography apparatus
Variety of items made by 3D printing [10]

Stereolithography is an additive manufacturing process that works by focusing an ultraviolet (UV) laser on to a vat of photopolymer resin.[11] With the help of computer aided manufacturing or computer aided design software (CAM/CAD),[12] the UV laser is used to draw a pre-programmed design or shape on to the surface of the photopolymer vat. Because photopolymers are photosensitive under ultraviolet light, the resin is solidified and forms a single layer of the desired 3D object.[13] This process is repeated for each layer of the design under the 3D object is complete.

In models featuring an elevator apparatus, such as models made by Amtech[14] an elevator platform descends a distance equal to the thickness of a single layer of the design (typically 0.05 mm to 0.15 mm[citation needed]) into the photopolymer vat. Then, a resin-filled blade sweeps across a cross section of the layer, re-coating it with fresh material[citation needed]. The subsequent layer is traced, joining the previous layer. A complete 3D object can be formed using this process. Designs are then immersed in a chemical bath in order to remove any excess resin and cured in an ultraviolet oven.[citation needed]

Stereolithography requires the use of supporting structures which attach to the elevator platform to prevent deflection due to gravity. and to hold cross sections in place in order to resist lateral pressure from the resin-filled blade[citation needed]. Supports are created automatically during the preparation of 3D Computer Aided Design models and can also be made manually[citation needed]. With more expensive stereolithography models, these supports must be removed from the finished product manually.[citation needed]

Advantages and Disadvantages[edit]

One of the advantages of stereolithography is its speed; functional parts can be manufactured within a day.[3] The length of time it takes to produce a single part depends upon the complexity of the design and the size. Printing time can last anywhere from hours to more than a day.[3] Many 3D printers can produce parts with a maximum size of approximately 50×50×60 cm (20×20×24 in)[citation needed] and some printers, such as the Mammoth stereolithography machine (which has a build platform of 210×70×80 cm),[15] are capable of producing single parts more than 2 meters in length[citation needed]. 3D printed prototypes and designs are strong enough to be machined and can also be used to make master patterns for injection molding, thermoforming, blow molding, and various metal casting processes.[citation needed]

Although stereolithography can be used to produce virtually any synthetic design,[12] it is often costly; the cost of photopolymer resin ranges from $80 to $210 per liter, and the cost of a 3D printer itself ranges from $100,000 to more than $500,000.[citation needed]

Recently, public interest in stereolithography has inspired the design of several consumer models of 3D printer which feature drastically reduced prices, such as the Titan 1 by Kudo3D, the Ilios HD by GizmoForYou, the Form 1 by Formlabs, the Pegasus Touch by FSL3D, and the Nobel 1.0 by XYZPrinting. There has also been a reduction of the cost of photopolymer resins, with USA based providers such as MakerJuice Labs offering consumers photopolymer resins with prices as low as $55 per Liter, and European based providers such as spot-A Materials offering materials for €68 per Liter.[citation needed]

See also see[edit]


  1. ^ Juursema, Jonathan. Felix 3D Printer- Printing Head. 2014. Wikimedia Commons. Web. 15 Nov. 2015. <>.
  2. ^ a b U.S. Patent 4,575,330 (“Apparatus for Production of Three-Dimensional Objects by Stereolithography”)
  3. ^ a b c d Hull, Chuck. “On Stereolithography.” Virtual and Physical Prototyping. Vol 7. (2012): 177. Web. 11 Oct, 2015
  4. ^ a b Gibson, Ian, and Jorge Bártolo, Paulo. “History of Stereolithography.” Stereolithography: Materials, Processes, and Applications. (2011): 41-43. Web. 7 October 2015.
  5. ^ 3D Systems Inc Company Info
  6. ^ Stereolithography
  7. ^ What is Stereolithography?
  8. ^ Jacobs, Paul F. “Introduction to Rapid Prototyping and Manufacturing.” Rapid Prototyping and Manufacturing: Fundamentals of Stereolithography. 1st Ed. (1992): 4-6. Web. 7 October 2015.
  9. ^ B. Asberg, G. Blanco, P. Bose, J. Garcia-Lopez, M. Overmars, G. Toussaint, G. Wilfong and B. Zhu, "Feasibility of design in stereolithography," Algorithmica, Special Issue on Computational Geometry in Manufacturing, Vol. 19, No. 1/2, Sept/Oct, 1997, pp. 61–83.
  10. ^ Kline, Doug. Cubify 3D Printing. 2012. Los Angeles, CA, USA. Wikimedia Commons. Web. 15 Nov. 2015. <>.
  11. ^ Crivello, James V., and Elsa Reichmanis. "Photopolymer Materials and Processes for Advanced Technologies." Chemistry of Materials Chem. Mater. 26.1 (2014): 533. Print.
  12. ^ a b Lipson, Hod, Francis C. Moon, Jimmy Hai, and Carlo Paventi. "3-D Printing the History of Mechanisms." Journal of Mechanical Design J. Mech. Des. (2004): 1029-033. Print.
  13. ^ Fouassier, J. P. "Photopolymerization Reactions." The Wiley Database of Polymer Properties 3 (2003): 25. Print.
  14. ^ "Stereolithography (SLA)". Retrieved 2015-11-16. 
  15. ^ Mammoth stereolithography: Technical specifications.


  • Kalpakjian, Serope and Steven R. Schmid. Manufacturing Engineering and Technology 5th edition. Ch. 20 (pp. 586–587 Pearson Prentice Hall. Upper Saddle River NJ, 2006.

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