High-consistency rubber (=HCR) is typically processed in the extrusion process into tubes or profiles. Because of the excellent properties in terms of flexibility down to low temperature, physiological harmlessness and the bride service temperature range from -80 to 250°C, there are a great number of applications for silicone rubber; especially in the field of automotive, food sector or medical engineering. During extrusion processing, there are some special phenomena, for example die-swelling. Die-swell means the swell of the extrudate after leaving the die. Due to the high requirements in terms of dimensional tolerance and the fact, that there is no calibration in the process line during extrusion of rubber, the manufacturer needs a lot of experience. With today's state of the art technology according to the used material, the process parameter are not changed to achieve the right dimensions, but the geometry of the die according to the used operating point will be customized. Those modifications are very time-consuming and because of that very expensive. The goal of this study is to identify the most influencing process parameters on the dimensional geometry of the extrudate by the help of design of experiment (=DoE) during the extrusion process of silicone rubber with a vertical extrusion line. It could be shown that the screw speed and as a consequence of that, the melt pressure and the vulcanisation temperature are the most influencing factors on the dimensional geometry of the extrudate. A profound knowledge of the whole process allows the manufacturer to change possible fluctuations in the dimension of the extrudate during processing by the change of chosen process parameters in an easy way. The running process does not have to stop or fundamental constructive changes at the die are not necessary.