the invention relates to a method and an injection - moulding nozzle for producing injection - moulded parts from plastic with an injection mould , wherein the plastic melt in the form of at least one ribbon - like strand of melt is injected through a nozzle slit into a cavity of the injection mould before the injection - moulded part is demoulded once the plastic melt has solidified . in order to provide advantageous injection - moulding and demoulding conditions , it is proposed that the plastic melt is exposed to heat in the region of the sprue during solidifying in the cavity and that the sprue is torn off during demoulding of the injection - moulded part along the nozzle slit in the region of the sprue as a result of the temperature gradient between the solidified injection - moulded part and the plastic melt .