Basically, stereolithography is a process in which liquid photopolymer is cured in a tank in a targeted manner by light-activated polymerisation.

The component to be manufactured must first be read in by CAM software as a CAD model, usually in STL format. The optimal orientation of the component to the manufacturing platform is then determined in this CAM software. Critical overhangs must be connected to the building board via so-called support structures in order to realize the component in the desired geometry. However, the aim is to use as few support structures as possible in this process, as these have to be removed from the component afterwards. After determining the orientation, the so-called "slicing" takes place. The layer-by-layer information of the component required for the system is generated.

Originally, in stereolithographic processes, polymerization was carried out using a UV laser. However, this can also be replaced by LEDs or halogen lamps. This technology is known as "Large Area Maskless Photopolymerization" (LAMP) or "Digital Light Projection" (DLP). The exposure can take place both from above and from below. Since the DLP process does not work point by point, but rather cures the entire layer at the same time, components can be manufactured much faster than when exposed to UV lasers.

The stereolithographic process is characterized above all by the high level of detail. Commercially available printers achieve a lateral resolution of up to approx. 50 µm, with minimum layer thicknesses of up to approx. 25 µm. In this way, even extremely filigree structures can be manufactured with great precision.

With the use of stereolithography, the possibilities in the area of CAD/CAM-supported production at CADdent have expanded by many structures. Although model production was already possible in subtractive manufacturing, but was expensive, these structures can now be offered economically for laboratories.

Stereolithographic production is particularly widespread in the 3D printing of resins. In the dental industry, primarily models, trays and drilling templates are manufactured using this process. However, resin 3D printing is also ideal for the manufacturing of burnable component to produce in a casting mold.

In January 2022, we at CADdent also introduced the ceramic 3D printing process and have since been able to produce ceramic components using an additive manufacturing process.

The so-called LCM process (Lithography-based Ceramic Manufacturing) is used for this. This is closely related to classic stereolithography. Very fine ceramic particles are mixed into the liquid, light-curing polymer. During the subsequent shaping process using light curing, the ceramic particles are enclosed in the cured resin. The component created after shaping – which in this state is referred to as a green body – is thermally freed from the plastic particles in the subsequent “de-binding process”. In order to obtain the final ceramic component, the material is sintered after this process - as you already know from subtractive processes such as milling zirconium - at temperatures of well over 1000°C in some cases. This post-process gives the ceramic component its desired material properties.