Method for the production of the internal toothing on planetary roller extruders with a central spindle, planetary spindles and housing, wherein the internal toothing is located directly in the housing, or a sleeve is provided in the housing opening and the internal toothing is located in the sleeve, wherein the planetary spindles mesh both with the central spindle and also with the internal toothing and the planetary spindles revolve around the central spindle and in the housing or in the sleeve wherein the shaping of the teeth of the internal toothing is effected by means of spark erosion, wherein the housing or the sleeve is in a liquid dielectric, such that when the electrode (12, 30) is inserted into the housing or when it is inserted into the sleeve, the dielectric fills the gap between the housing or sleeve and the electrode (12, 30), wherein an electric voltage is applied to the housing or to the sleeve and to the electrode (12, 30), such that sparks are generated from the inner surface of the housing or the sleeve and reach the electrode (12, 30) and material is worn away from the inner surface of the housing or sleeve, wherein,by taking into account the required gap for the erosion,an electrode (12, 30) with an external toothing is used that can mesh with the internal toothing, characterised by the use of an electrode (12, 30) that - starting at the end face of the electrode (12, 30) - is provided with a curvature on the electrode casing, wherein electrodes (12, 30) are used with curvatures having the following radius Tool size Radius of curvature minimummaximum minimummaximum 50 150 2mm 6mm 150 300 5mm 8mm 350 400 5mm 10mm 500 1000 5mm 20mm wherein the internal toothing is located directly in the housing, or a sleeve is provided in the housing opening and the internal toothing is located in the sleeve, wherein the planetary spindles mesh both with the central spindle and also with the internal toothing and the planetary spindles revolve around the central spindle and in the housing or in the sleeve wherein the shaping of the teeth of the internal toothing is effected by means of spark erosion, wherein the housing or the sleeve is in a liquid dielectric, such that when the electrode (12, 30) is inserted into the housing or when it is inserted into the sleeve, the dielectric fills the gap between the housing or sleeve and the electrode (12, 30), wherein an electric voltage is applied to the housing or to the sleeve and to the electrode (12, 30), such that sparks are generated from the inner surface of the housing or the sleeve and reach the electrode (12, 30) and material is worn away from the inner surface of the housing or sleeve, wherein,by taking into account the required gap for the erosion,an electrode (12, 30) with an external toothing is used that can mesh with the internal toothing, characterised by the use of an electrode (12, 30) that - starting at the end face of the electrode (12, 30) - is provided with a curvature on the electrode casing, wherein electrodes (12, 30) are used with curvatures having the following radius Tool size Radius of curvature minimummaximum minimummaximum 50 150 2mm 6mm 150 300 5mm 8mm 350 400 5mm 10mm 500 1000 5mm 20mm