Thermoverschlussdüse und Verfahren zum Beheizen einer solchen

A thermal shut-off nozzle for the plastifier unit (PU) of an injection moulding machine or extruder, especially for coupling to a mould or a mould closer, comprising a housing (12) with one side connected to the PU and the other to a nozzle top which can be heated (NT) (28, 38), an inlet (14) for the melt, an outlet on the NT and a flow path between inlet and outlet, in which at least part of the NT (28) consists of electrically conductive ceramic which acts as a resistance heater under an applied voltage. Independent claims are included for (1) a method (M1) for heating the NT (see above) with a continuously-maintained electrical connection between a power supply and both the ceramic (ECC) and a coupling element, in which the current is controlled by the connection and disconnection of the NT from the coupling part (2) another method (M2) for heating the NT with the aid of a connection to a power supply through two direct connections to the ECC, in which the NT is heated before discharging the melt by applying a voltage to the ECC and then maintaining the voltage for at least a given time during the discharge process .