Method for cutting metallic threads

A machining method for a CNC-lathe for forming a predefined thread in a work piece, the method comprising the steps of:

• providing a metal work piece;
• providing a threading tool, wherein the threading tool includes a first cutting edge and a second cutting edge;
• rotating the metal work piece around a rotational axis thereof;
• moving the threading tool along a longitudinal direction through a set of passes, wherein the longitudinal direction is parallel to or coinciding with the rotational axis;
• during a first pass oscillating the threading tool in a radial direction at a first frequency such that the threading tool moves between a first radial distance and a second radial distance, where the first radial distance is greater than the second radial distance;
• during a second pass oscillating the threading tool in a radial direction at a second frequency such that the threading tool moves between a third radial distance and a fourth radial distance, where the third radial distance is greater than the fourth radial distance and smaller than the first radial distance, where the fourth radial distance is smaller than the second radial distance, and where the third radial distance greater than the second radial distance;
• during a last pass moving the tool without oscillation in the radial directions;
• setting the second frequency different to the first frequency;
• and
• arranging the second pass such that for each oscillation of the second pass a trajectory of the second pass intersects a trajectory of the first pass two times or more than two times.