Stereolithography - precision and detail
Stereolithography , SLA, is one of the finest 3D printing techniques. With its help, extremely small and fine details can be printed with a perfectly smooth surface that does not require any additional processing. For the building material, photopolymer is used, in contrast to powder fillings and filaments. Photopolymer is a material that changes its structure under ultraviolet light, when it changes from a liquid state to a solid state.
SLA printers work with a tube filled with photopolymer and a platform that moves along a vertical axis. The machine starts building the model layer by layer with the help of an extremely precise laser or UV lamp. When one layer hardens the platform is raised (or lowered depending on the type of printer) and makes a new fine layer of polymer. The laser constantly follows the path set by the software until the object is finished. After that, the operator gently separates the object from the work platform. Depending on the printer itself and the type of polymer, it is possible that the object needs to be immersed in a bath of water to remove excess polymer, treated in a UV oven to further harden it, or immediately ready for further use. Support structures are used for hanging parts, otherwise printing would be impossible.
The key advantage is extremely high precision and printing speed. A small layer thickness of 0.02 millimeters gives a perfectly smooth surface and precision. The disadvantage is the very high cost of use.
The size of the working chamber depends on the model itself and can be very small (jewellery printers) and large prototypes can be produced.
Objects produced with SLA 3D printing technology have extremely high resolution and quality and often do not require any additional processing. They can be polished and painted.