Methods of 3D Printing - Rapid Prototyping and Manufacturing

   Stereolithography

The term “stereolithography” was coined in 1986 by Chuck Hull. 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 photopolymer. 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. It  is currently based in Rock Hill, SC. Stereolithography had success in the automotive industry. The technology continues to find innovative uses in countless fields of study.


Stereolithography works by focusing an ultraviolet (UV) laser on to a vat of photopolymer resin. With the help of computer aided manufacturing or computer aided design software (CAM/CAD), 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. This process is repeated for each layer of the design until the 3D object is complete.

• Digital Light Processing

The digital micromirror device (DMD) found at the core of DLP technology enables companies to develop uniquely fast and accurate 3D printers. These printers make use of liquid photopolymer resins to build objects. For each crosssectional slice of the object, the DMD projects patterned light
that selectively exposes and hardens the resin. Because an entire layer is exposed with a single pattern, fast build speeds are achieved independent of layer complexity. Projection optics can also be used to control the resolution on the image plane and adjust the layer thickness, leading to smooth and accurate finished parts. These benefits, combined with its proven reliability, make DLP technology the ideal solution for 3D printing systems.
http://www.ti.com/lit/ml/dlpb008a/dlpb008a.pdf




• Inkjetted photopolymers
• Thermoplastic extrusion
• Selective Laser Sintering of plastics
• Selective Laser Melting of metals
• Blown metal powder • Welding
• Sand binding
• Binder jetted into metal powder (by ExOne)
• Smooth Curvature Printing (by Solidscape)
• Selective Deposition Lamination (by Mcor Technologies)
• Hybrid CNC



http://3dprintingindustry.com/3d-printing-basics-free-beginners-guide/processes/