Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Thin walled tube threading

Thin walled tube threading

Thin walled tube threading

I have an 6061 aluminum tube (1"OD x 0.058" wall) that requires an end cap on one end and a retaining ring on the other to keep parts inside. The tube is turned down to 25mm OD and anodized for use as a linear shaft. For the past while we've been having the end caps welded in place, then turning the tube to size. We would like to move away from welding for a couple different reasons.

The end cap is subject to axial loads of up to +/- 200 N, high vibrations, and an operating temperature range of -20° to 70°C. I'm trying to figure out if threading the tube and end cap is a suitable alternative. CNC single point threading is the preferred method of manufacture and they would be assembled with permanent thread locker.

Say I spec'd a thread with a minor diameter equal to the ID of the tube and a thread depth of ~1/3 the wall thickness. Is it sufficient to choose a thread engagement length that results in a thread shear area able to withstand the loads by some margin? How do I go about determining the effect of the cyclic loading on the threads? Is anodizing such a fine thread kosher, or should I mask off the threads before anodizing?

Thanks in advance for any help on the matter!

RE: Thin walled tube threading

You could probably swage the end of the tube to a smaller OD, forcing the ID small enough to retain internal parts, depending on the design.
Or curl and/or fold the end over like a shotgun shell is closed.
Or emboss a ring near the end of the tube over a plug with an annular groove in its OD. I think this can be done with electromagnets with impressive speed. Or mechanically with a roller.

If the closed end of the tube needs to be watertight, consider forming the whole tube by impact extrusion from a thick disc.

Mike Halloran
Pembroke Pines, FL, USA

RE: Thin walled tube threading

Try shaft-locking compound and a close slip fit. No need for threads.

RE: Thin walled tube threading


I think that any finish on your threads other than anodizing, is not kosher. Aluminium galls.


RE: Thin walled tube threading

Use the same technique used for push-nuts or Legris fittings.

RE: Thin walled tube threading

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close