Heating device for locally heating of an injection mold cavity wall, comprising: a base plate, an actuator located on the base plate, to perform a linear movement; a heated stamp connected to the actuator and driven by the actuator, to perform a linear movement in direction to and from the injection mold cavity wall; wherein the heated stamp is located below the base plate and the actuator is located on top of the base plate, and wherein the base plate comprises an opening through which a pin extends for transferring the linear movement from the actuator to the heated stamp.