Liquid silicone rubber (=LSR) is used for applications in the medical and electrical industries. The excellent properties and the physiological benign properties make this material attractive for the ever rising number of applications with high requirements. After processing, the material is post-cured in order to improve the mechanical properties and to remove all volatile components, e.g. low-molecular products. In this study, different types of liquid silicone rubber were manufactured on an all-electric Arburg Allrounder 370A in the liquid injection molding process with the same processing parameters. After processing, all specimens were post-cured in a circulating air oven. The duration and the rate of this heat treatment were variable. In order to identify the influence of the different heat treatments, the mechanical properties were investigated by different tests: impact resilience, hardness, change of mass and tensile test. It was found out that, according to the testing method, the heating rate has a higher effect on the properties in contrast to the duration of the heat treatment. Some mechanical properties improve with rising temperature until a special temperature level. After passing that temperature level, the properties decrease. Post-curing is an important after-treatment process for liquid silicone rubber. It was shown that according to the application and the specimen geometry, the process could be reduced in its time in order to optimize the required properties.