I am wondering how the screw top of a container made of either aluminium or brass is manufactured at scale. A picture of the sort of thing I am talking about is below. Currently the only method I can think of is hydroforming. Can anyone enlighten me?

Example Image

  • 1
    $\begingroup$ Could it be rolled? $\endgroup$
    – Solar Mike
    Oct 28, 2018 at 14:19
  • $\begingroup$ @Solar Mike I did wonder that. However it typically looks like the entire surface has been bent to form the threads (so you can see the negative of the thread on the inside) making me think it isn't made using that sort of process $\endgroup$ Oct 28, 2018 at 14:27
  • $\begingroup$ That's what rolling does: a small wheel on the inside as the container is rotated... The material is thin enough to deform to give a simple thread... $\endgroup$
    – Solar Mike
    Oct 28, 2018 at 14:32
  • $\begingroup$ Ah I didn't think about a smaller wheel on the inside to support it, that does seem like a good method then $\endgroup$ Oct 28, 2018 at 14:35
  • $\begingroup$ Hydroforming is relatively expensive. $\endgroup$ Oct 28, 2018 at 21:25

1 Answer 1


These threads are rolled. The blank is automatically fed to sit around a central wheel which has the form of the thread. An external arm with the opposing half of the form then lowers to apply pressure and form the threads, before being automatically ejected from the central wheel, ready for the next part.

This video https://www.youtube.com/watch?v=HykVRyTsV20 shows a machine forming the threads on a cap, but the process is identical for the container itself.


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