Abstract: A power-operated chuck for a tool spindle of a machine tool includes a chuck body and at least one chucking device which is guided in a radial guide of the chuck body and which, for exerting a desired chucking force on a workpiece chucked in the chuck, can be adjusted relative to the chuck body by a chucking-force generator via at least one drive member arranged in the chuck body. At least one chucking device has a measuring device for measuring a chucking force exerted by the chucking device on the workpiece chucked in the chuck and an evaluating device for evaluating the chucking force measured by the measuring device.

Abstract: A rotatable chuck for securing a workpiece in a machine includes a base element having a center and a plurality of jaw elements movable relative to the center. The jaw elements are movable to clamp the workpiece. The jaw elements exert a measurable clamping force on the workpiece. The clamping force exerted on the workpiece is measured and the jaw elements are moved relative to the center to vary the clamping force exerted on the workpiece. A comparator compares the measured clamping force to a predetermined clamping force and the jaw elements are moved, as the chuck is rotating, to adjust the clamping force on the workpiece relative to the predetermined clamping force.