Balance is a major factor in determining the reliability and service life of turbine rotors used in jet engines or power plants. The task of balancing a completed rotor can be greatly simplified if the individual blades are first measured and sorted according to static unbalance moment. They are then assembled in the rotor in matched pairs, resulting in an assembly that is approximately balanced. The blade is then inserted in the adapter. A force transducer determines the moment.
Most Manufacturers use a knife edge and load cell to measure moment.
This results in poor accuracy and reliability Machines manufactured by Space Electronics use crossed-web flexure pivots and force restoration technology, resulting in an instrument which is at least 10 times more accurate than other methods and is also more resistant to damage in a production environment. In our scale, a laser detects a shift due to blade moment and a feedback circuit applies an electromagnetic force to counteract the deflection. The current applied is converted to a measurement of force. Our pivot consists of strips of spring steel which are oriented to create a single center of rotation . We do not use knife edges, because they are not capable of the 0.000,050 inch pivot accuracy required.