Liquid Additive Manufacturing (LAM) describes the process of processing liquid silicone rubber (LSR). It is one of the latest manufacturing processes that can be used to produce 3D printed parts from LSR. LAM is one of the extrusion-based additive manufacturing processes. The LSR, which consists of two components, is conveyed into a mixer and extruded through a die onto a build platform. The silicone is then thermally crosslinked, layer by layer to create a finished component. In contrast to other silicone additive manufacturing processes, the generated part can be used directly because it is already completely vulcanized.

As with all extrusion-based manufacturing processes, the printing parameters significantly influence the printing result. In this work, different liquid silicone rubber, which are usually used in injection molding, will be investigated with regard to the influence of the printing parameters on the isotropy. For this purpose, various liquid silicone rubbers are produced by injection molding as well as by the LAM process, because 3D printed parts should ideally have the same properties as injection molded ones.

In order to determine the influence of the printing parameters on the component quality, the following parameters are investigated during this work, the influence of the temperature and the extrusion multiplier. For this purpose, in-line process parameters such as the temperature of the build platform or the pressure in front of the die are recorded on the one hand, and on the other hand the printed components are characterized mechanically and optically.

For the mechanical tests, elongation at break, tensile strength and hardness are compared. Optical analysis is carried out by means of a confocal laser microscope. Surface roughness is compared between the manufactured parts and the printing results are evaluated.

Subsequently, all test results are compared to determine the influence of the significant process parameters.