×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

Indium as a Vacuum Seal - torque specification for screws

Indium as a Vacuum Seal - torque specification for screws

Indium as a Vacuum Seal - torque specification for screws

(OP)
Hi,

We have a system that functions at ~10^-6 Torr. Two of the gaskets we use are an Indium wire of 1mm. One is 350mm in perimeter and one is 280mm.
Both wires are in a standard gland, and are tightened with 8 NC10-24 screws. Currently there's no torque specification for these screws, and I'm trying to define one.

I'm using A.Roth's book: Vacuum Technologies, p. 308 in order to try and determine the force needed to exert on the seal.
It gives two examples: 0.8mm dia. wire: 7 kg/cm, and 1.5mm dia. wire: 56 kg/cm.
I sort of extrapolated a 25 kg/cm requirement for the 1mm dia. wire I'm using.
Next I tried calculating the torque needed for each screw, and got ~9.2 in-lbf.

This seems a rather small value, since most general torque charts I found stated around 25-30 in-lbf. Therefore, I'm a little worried give the 9.2 in-lbf. spec for our system.
What do you think? What happens I theoretically I specify a 25 in-lbf torque and I exert a force far greater than the theoretical calculated?

Thanks

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!


Resources