Stereolithography is a 3D print service technique which employs the use of photo polymerization to create a solid object from a liquid material. A process termed as digital light processing exposes liquid polymer to light emitted from a DLP projector. Digital light processing is done under safe light conditions. The vat of polymer gets hardened due to the exposure. Small portions of the build plate are removed to expose more of the liquid polymer to light. This procedure is repeated till the entire object has been completed. Draining the liquid polymer from the vat leaves behind the solid object. One such example of the digital light processing rapid prototyping system is the ZBuilder Ultra.
In the Objet PolyJet 3D print service system, an inkjet printer sprays ultra-thin layers of photopolymer material, one layer at a time, until the object is completed. The layers are approximately 16 micron in thickness. Immediately after a layer is jetted, it gets cured by ultraviolet light, in order to build models that do not need post curing treatment. These models can come into immediate use. The supporting material has a gel-like nature, to be able to support complex geometry. It is removed mechanically and/or by water jetting. This method can also be applied to elastomers.
When it comes to 3D print service of ultra-small features, multiphoton photopolymerization is a highly useful procedure. It is primarily employed for 3D micro fabrication purposes. In this technique, a focused laser traces out the object in a block of gel. Curing of the gel for solidification is done in only those parts which are subjected to the focus of the laser, since the photoexcitation exhibits a nonlinear nature. The excess gel is then washed away. Parts that are smaller than 100 nm can be easily fabricated with the help of this process, besides the construction of moving/ interlocked parts.
Another approach to 3D printing service is the use of LEDs to solidify a synthetic resin. So far, inkjet printing is the most economic technique. It does not have the requirement of toxic chemicals like in the Stereolithography procedure. It costs less, is a speedy process, and is easy to handle. After the printing process is completed, not much finishing work is required. The printer itself is sufficient to clear away the powder that is left behind. In order to strengthen bonded powder prints still further, wax can be used. Another alternative is thermoset polymer impregnation.