Chipless forming of external threads

External thread rolling and repairing by hand

In addition to thread cutting, thread rolling is of great importance especially in series production. Compared to cut threads, rolled threads have a higher strength due to the undestroyed grain of the workpiece surface. And because of the lower surface roughness, they are less susceptible to rust than cut threads.

Up to now, rolled threads could only be produced by machine. But recently the SilberTool company has started offering the world’s first tools for hand-rolling external threads. In contrast to thread cutting, no chamfering or chip breaking is necessary, and the tool cannot be accidentally set at an angle, as the thread is rolled from the centre outwards. A peculiarity of thread rolling, however, is the material flow that occurs during cold forming: the material is displaced from the core of the thread profile into the tips, and there is no change in volume. As a result, the preparation diameter during thread rolling is usually slightly below the flank diameter of the subsequent thread.

With the SilberTool® hand tools it is also possible to re-form damaged external threads to their original condition within seconds. No material is removed and the thread is not weakened in the process as would be the case with a thread cutter or thread file. The opposite is the case: the cold forming that takes place during a repair with the SilberTool® hand tool increases the strength of the thread.

Further information can be found on the manufacturer’s website:

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