We are able to stamp retention features on parts in line with production. There are several geometries but the "star" is our most common, 4 raised flutes that give both anti-pull out and anti-rotational strength. When there is a need for a feature that doesn't protrude from wire diameter we have inscribed squares or grooves that both also give anti-rotational and anti-pull out force.
The cut-off process would seem simple but is critical to our production. Because we are forming metal into shape without removing (or adding) any material we have to have tight control of the volume of metal going in our dies. We achieve this by having an extremely accurate feed length along with a very smooth cut. Our 4-way cutters open to allow the wire to feed and clear the retention feature, then close and grip one side of the wire before the other cutter passes through and shears it cleanly.
The rolling die is where the magic happens. We roll the cut blank of wire down a carbide die, and with each revolution, the part forms more and more toward its final shape. We are putting whatever end radius is specified in this step but we also can raise a collar, put in a groove, add a knurl or spline, put in threads, or any number of other design elements that are radial around the part.