CNC Metal Spinning

The figure illustrates the typical setup and the processes involved in multi-pass spinning.

The blank, in this case a plain, sheet-metal disc, is concentrically clamped against the mandrel by the tailstock and driven via the main spindle. Rotating at high speed, the workpiece is then formed by the spinning roller following a pre-set path to produce a series of strokes or passes. In so-called 'continuous' spinning, the roller remains in permanent contact with the workpiece and is driven by frictional contact, the translated motion being generated by the cross-slide. A number of passes are normally needed to form the part onto the mandrel which also prevents premature failure through splitting or buckling.
1. Disc Blank 2. Spinning Roller 3. Mandrel 4. Clamping Plate 5. Blank Support Unit
6. Trimming Plate 7. Spindle 8. Cross Slide 9. Tailstock

The blank support attachment in the forward position, is used in the early stages of the spinning operation. Its purpose is, by means of a pre-set pressure, to apply an axial, compensating load to the workpiece in the zone being worked. Sandwiched between the blank support and the work roller, the metal is thus less prone to failure through buckling. For lighter gauges, the blank is supported by a disc, as illustrated, whilst a cone-shaped roller is used for thicker materials. The roller or disc is usually driven by contact with the blank.


To improve finish and accuracy, intermediate and finishing passes, generally called planishing passes, are made. The planishing passes are designed to remove any waviness resulting from different stages in the spinning process. High feed rates are usually applied to minimize tangential flow and improve accuracy.



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