Abstract: A method for improving the performance of a gas turbine, in which a hub annually surrounding a rotor is machined when the rotor is in the non-stacked state and hot shield elements that are arranged on the hub are exchanged. The method includes a) dismantling of the rotor together with the surrounding hub from the gas turbine; b) horizontal mounting of the rotor in the non-destacked state; c) removing of all heat shield elements of the row which is arranged as the last row in the flow downstream direction; d) mechanical machining, in particular complete removing of the hub projection; e) machining of at least some of the existing cooling air bores and/or producing of new cooling air bores, and f) mounting of new heat shield elements, the design of which differs from that of the heat shield elements which were removed in step c).

Abstract: Provided is a mobile CNC machining machine which is designed to machine a rotor of a turbomachine, wherein the turbomachine is a rotor of a steam turbine, including an x-axis, a y-axis and a z-axis which are arranged perpendicular to one another, a baseplate, a stator which is arranged on the baseplate and is movable relative to the baseplate along the x-axis, and a tool module which is held on the stator and is movable along the y-axis and along the z-axis and is designed to accommodate a machining tool wherein, guided along a circular-arc-shaped convex guide disposed on the stator, the tool module is movable about a c-axis which extends parallel to the x-axis; in that the z-axis intersects the c-axis; and in that the y-axis extends tangentially to a circular path, of which the c-axis is the center point.