Schunk’s Rota NCR-A Six-Jaw Power Lathe Chuck Features Efficient Design

Schunk's power lathe chuck enables maximum roundness


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The Schunk Rota NCR-A sealed six-jaw pendulum compensation chuck has seals at the jaw interface and the piston to prevent grease from being washed out. This design also keeps the chuck from gradually losing clamping force. Even in the case of low clamping forces, the chuck is said to function precisely, while the seals block chips and dirt from entering the chuck body. As a result, the chuck requires less maintenance, meaning it doesn’t have to be lubricated or cleaned as often, according to the company.


The Rota NCR-A consists of a central chuck piston, containing three inner pendulums aligned at 120 degrees. Each pendulum is connected to two base jaws. This ensures workpiece centering between six contact points, which can be adjusted in pairs. As the clamping forces are directed toward the chuck, optimum centering is achieved without redundant dimensioning of the workpiece. The chuck’s jaws oscillate precisely, adapting to the workpiece, which is said to ensure maximum roundness. Compared with the three-jaw chuck clamping, this reduces deformation of ring-shaped workpieces by a factor of 10. For finish machining or clamping of pre-turned surfaces, users can clamp the pendulums of the chuck in center position, enabling all six jaws to move concentrically. The clamping force between the first and second clamping operation can be varied by the pressure reduction on the clamping cylinder. The rigid chuck body and the long jaw guides ensure a high repeat accuracy and precise machining results.


The flat chuck design is said to enable plenty of space in machine shops for users to work. The Rota NCR-A uses standard Schunk chuck jaws, which the company says saves cost and time-consuming special designs, increases flexibility and reduces setup effort. The chuck is available in sizes from 190 mm to 1,000 mm diameters with maximum clamping forces between 36 kN and 300 kN and jaw strokes from 6 mm to 25 mm. The power lathe chucks sizes 190 to 225 are equipped with tongue and groove; size 250 chucks are equipped with a versatile fine serration (1.5 mm × 60 degrees or 1/16'' × 90 degrees); sizes 630 and up can be used on vertical lathes. Depending on the chuck size, the pendular compensation amounts between ± 1 mm and ± 6 mm, and the maximum speed is 600 rpm to 4,000 rpm.


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