A method of filling the cavity of a tool used for production of a molded part from a melt, especially the cavity of an injection molding machine, wherein the melt is introduced into the cavity under pressure and is subjected to a dwell pressure towards the end or at the end of its flow path. The tool wall temperature is determined at the end of the flow path of the melt and the switching point for switching to the dwell pressure is determined from the increase of the tool wall temperature.