There are three main technics for making fasteners: Cold forming, hot forming and cutting processes.
The most common technics is cold forming, a process that reworks the part in cold condition, in several steps with possible post-processing. The production rate is high and is suitable for large series.
Hot forming means that the material is heated and reformed in a press. The method does not give as precise tolerances and high production rates as cold forming, but lower tooling costs and the ability to produce larger dimensions make this manufacturing method sometimes preferred. Post-processing of certain properties is often necessary.
The third major technics, cutting processes, is very flexible and suitable for smaller series but has a higher cost because material is shed during the processing instead of being transformed. The fatigue strength also becomes somewhat lower because the material’s tension is not maintained as in the cold and hot forming process.