Stereolithography
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| History of printing |
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| Woodblock printing (200) |
| Movable type (1040) |
| Printing press (1454) |
| Etching (ca. 1500) |
| Mezzotint (1642) |
| Aquatint (1768) |
| Lithography (1796) |
| Chromolithography (1837) |
| Rotary press (1843) |
| Offset printing (1875) |
| Hectograph (19th century) |
| Hot metal typesetting (1886) |
| Mimeograph (1890) |
| Screen printing (1907) |
| Spirit duplicator (1923) |
| Dye-sublimation (1957) |
| Phototypesetting (1960s) |
| Dot matrix printer (1964) |
| Laser printing (1969) |
| Thermal printing (ca. 1972) |
| Inkjet printing (1976) |
| Stereolithography (1986) |
| Digital press (1993) |
| 3D printing (ca. 2003) |
Stereolithography (SLA) is an additive manufacturing technology for producing models, prototypes, patterns, and in some cases, production parts.
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[edit] Technology description
Stereolithography is an additive manufacturing process using a vat of liquid UV-curable photopolymer "resin" and a UV laser to build parts a layer at a time. On each layer, the laser beam traces a part cross-section pattern on the surface of the liquid resin. Exposure to the UV laser light cures, solidifies the pattern traced on the resin and adheres it to the layer below.
After a pattern has been traced, the SLA's elevator platform descends by a single layer thickness, typically 0.05 mm to 0.15 mm (0.002" to 0.006"). Then, a resin-filled blade sweeps across the part cross section, re-coating it with fresh material. On this new liquid surface, the subsequent layer pattern is traced, adhering to the previous layer. A complete 3-D part is formed by this process. After building, parts are cleaned of excess resin by immersion in a chemical bath and then cured in a UV oven.
Stereolithography requires the use of support structures to attach the part to the elevator platform and to prevent certain geometry from not only deflecting due to gravity, but to also accurately hold the 2-D cross sections in place such that they resist lateral pressure from the re-coater blade. Supports are generated automatically during the preparation of 3-D CAD models for use on the stereolithography machine, although they may be manipulated manually. Supports must be removed from the finished product manually; this is not true for all rapid prototyping technologies.
This process is a more expensive form of rapid prototyping.
[edit] Advantages and disadvantages
Stereolithography has many common names such as: 3D printing, optical fabrication, photo-solidification, solid free-form fabrication and solid imaging. One of the appealing aspects about SL is that a functional part can be created within one day. The length of time it takes to produce any one part depends on the size and complexity of the project and can take anywhere from a few hours to more than a day. Most SL machines can produce parts with a maximum size of approximately 50×50×60 cm (20"×20"×24") and some, such as the Mammoth stereolithograhy machine, are capable of producing parts of more than 2 m in a single piece (the Mammoth has a build platform of 210×70×80 cm)[1]. Prototypes made by stereolithography can be very beneficial as they are strong enough to be machined and can be used as master patterns for injection molding, thermoforming, blow molding, and also in various metal casting processes. Although stereolithography can produce a wide variety of shapes, the process is often expensive – the photo-curable resin costs anywhere from $80 to $210 per litre. A stereolithography machine can cost from about $100,000 to more than $500,000.
[edit] History
The term “stereolithography” was coined in 1986 by Charles (Chuck) W. Hull.[2] Stereolithography was defined as a method and apparatus for making solid objects by successively “printing” thin layers of the ultraviolet curable material one on top of the other. Hull described a concentrated beam of ultraviolet light focused onto the surface of a vat filled with liquid photopolymer. The light beam draws the object onto the surface of the liquid layer by layer, causing polymerization or crosslinking to give a solid. Because of the complexity of the process, it must be computer-controlled. In 1986 Chuck Hull founded the first company to generalize and commercialize this procedure, 3D Systems Inc,[3] [4] [5] which is currently based in Rock Hill, SC. More recently, attempts have been made at constructing mathematical models of the stereolithography process, and designing algorithms that will automatically determine whether or not a proposed object may be constructed by this process.[6]
[edit] See also
[edit] References
[edit] Notes
- ^ Mammoth stereolithography: Technical specifications. materialise.com
- ^ U.S. Patent 4,575,330 (“Apparatus for Production of Three-Dimensional Objects by Stereolithography”)
- ^ 3D Systems Inc Company Info
- ^ Stereolithography
- ^ What is Stereolithography?
- ^ 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.
[edit] Bibliography
- 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.
[edit] External links
- Graphical Display of the Stereolithography Process: A resource page maintained by Laser Prototypes (Europe) Ltd,
- Castle Island's Worldwide Guide to Rapid Prototyping, with comprehensive information on rapid prototyping, rapid tooling, stereolithography and solid freeform fabrication technology products and services. Complete rapid prototyping service bureau listings.
- How Stereolithography (3-D Layering) Works from HowStuffWorks.com
- Manufacturing Engineering Centre (MEC), Cardiff University, UK
- Rapid Prototyping and Stereolithography animation – Animation demonstrates stereolithography and the actions of an SL machine.
- About 3D Systems, Company History
