Method of operating a needle valve nozzle in an injection moulding apparatus, the injection moulding apparatus comprising: - a needle valve nozzle having at least one outlet opening, - at least one shut-off needle which passes through the needle valve nozzle in a longitudinally displaceable manner along a stroke path of variable length and which is adjustable by a drive exclusively between an opening position and a closing position closing the outlet opening, and - a mould cavity, which is fluidically connected to the needle valve nozzle, comprising the following steps: a. Presetting at least one process parameter for the needle valve nozzle selected from the group comprising needle stroke speed and needle stroke acceleration; b. Adjusting the shut-off needle from its closed position to its open position according to the at least one process parameter with a continuous needle stroke speed defined before the adjustment; c. Injecting a quantity of fluid mass into the mould cavity; d. Moving the shut-off needle from its open position to its closed position according to the process parameter with a continuous needle stroke speed; e. Comparing the product formed in the mould cavity and/or at least one process parameter detected during injection with at least one predefined quality criterion to determine whether the mould cavity filling quantity was too large or too small, f. in the case of an injected mould cavity filling quantity that is too large: i. Increasing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. reducing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one changed value process parameter as a new predetermined process parameter, g. in the case of an insufficient injected mould cavity filling quantity i. Reducing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. increasing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one value changed process parameter as a new predetermined process parameter, h. Performing steps a to e and for g in an iterative manner until the comparison shows that the product meets the predefined quality criterion. - a needle valve nozzle having at least one outlet opening, - at least one shut-off needle which passes through the needle valve nozzle in a longitudinally displaceable manner along a stroke path of variable length and which is adjustable by a drive exclusively between an opening position and a closing position closing the outlet opening, and - a mould cavity, which is fluidically connected to the needle valve nozzle, a. Presetting at least one process parameter for the needle valve nozzle selected from the group comprising needle stroke speed and needle stroke acceleration; b. Adjusting the shut-off needle from its closed position to its open position according to the at least one process parameter with a continuous needle stroke speed defined before the adjustment; c. Injecting a quantity of fluid mass into the mould cavity; d. Moving the shut-off needle from its open position to its closed position according to the process parameter with a continuous needle stroke speed; e. Comparing the product formed in the mould cavity and/or at least one process parameter detected during injection with at least one predefined quality criterion to determine whether the mould cavity filling quantity was too large or too small, f. in the case of an injected mould cavity filling quantity that is too large: i. Increasing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. reducing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one changed value process parameter as a new predetermined process parameter, i. Increasing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. reducing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one changed value process parameter as a new predetermined process parameter, g. in the case of an insufficient injected mould cavity filling quantity i. Reducing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. increasing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one value changed process parameter as a new predetermined process parameter, i. Reducing the needle stroke speed for a subsequent iteration for moving the shut-off needle from its closed position to its open position and/or for moving the shut-off needle from its open position to its closed position, and/or ii. increasing a needle stroke acceleration for a subsequent iteration, and iii. Setting the at least one value changed process parameter as a new predetermined process parameter, h. Performing steps a to e and for g in an iterative manner until the comparison shows that the product meets the predefined quality criterion.