of the test masses and locations are compared and the test mass and location with the highest score is selected the factors may be weighted such that for example mass and tensile load are given greater weight in the scoring than other factors and the weighting may be altered in accordance with operational requirements a material deposition process is then applied to the rotor 40 to apply the selected mass to the selected location the material deposition process could preferably be carried out with the rotor mounted on the balancing machine since the scanning and rotor simulation steps can also be carried out with the rotor mounted on the balancing machine the rotor does not have to be manually handled during the balancing process the material deposition process may comprise a u201c net shape u201d deposition process in which the deposited weight has the required shape and mass to within predetermined tolerances alternatively the material deposition process may comprise a u201c near net shape u201d deposition process in which the deposited weight has a size and mass which is greater than the required size and mass where a near net shape deposition process is utilised additional material is added during the material deposition process which is then removed by a machining step in which material is removed from the weight until the shape and mass of the weight corresponds to the required shape and mass to within predetermined tolerances any one or more of several material deposition techniques could be used including for example blown powder direct laser deposition dld plasma welding tungsten inert gas tig welding metal inert gas mig welding pvd or cvd a preferred method for this process.