×
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

Aluminum with Steel screws
2

Aluminum with Steel screws

Aluminum with Steel screws

(OP)
We have 1/16" Aluminum sheeting screwed with steel self taping screws. The product gets heated 160°C maximum in a 50-70 % humidity environment. We are wondering how long (very approx.) could the thread hold the screw in place without being all "eaten up" by corrosion.

Thank you
Jonathan Dubé physics tech.

RE: Aluminum with Steel screws

You say steel screws.

Do you mean steel presumably zinc plated, or stainless steel.

KENAT, probably the least qualified checker you'll ever meet...

RE: Aluminum with Steel screws

In that aluminium thickness why don´t you use aluminium alloy rivets?

RE: Aluminum with Steel screws

(OP)
Yes...sorry, I meant Zinc screws.  I was about to change all the screws for Aluminium screws because of the corrosion (Zinc+Aluminium) But first, I need some advice about how fast corrosion can deteriorate the screw thread... I heard that there was no problem for about 2 years. On the other side, some told me that the chemical reaction Aluminium+Zinc would deteriorate threads pretty quicly and cause a nice little mess on the product.

RE: Aluminum with Steel screws

We used to avoid stainless fasteners into aluminium in Aerospace/Defense.

In fact we rarely threaded into aluminum at all, usually helicoil or similar.

On at least one design I remember using zinc plated steel pins in aluminium because of concerns over using stainless.

They lasted pretty well in a salt spray test, both with plain and anodized aluminium.

Of course this isn't threads where there are more traps etc so I guess I don't really know.

Sorry

KENAT, probably the least qualified checker you'll ever meet...

RE: Aluminum with Steel screws

The zinc coating will go first. It will sacrifice itself to protect the aluminum because it touches bare aluminum when it self tapping the aluminum sheet. So, nothing will happen to the aluminum thread as long as there is zinc on the screws. How long it will take this is a different question. In the aerospace business when aluminum sheet is riveted to the aircraft structure the instructions are to dip the rivets in a wet zinc chromate primer just before instaling the rivets.

RE: Aluminum with Steel screws

When I said they lasted pretty well I meant they were strcuturally sound.  They looked like #%@#$^@#.

If Aesthetics is a concern then in your environment zinc plated may be a concern.

KENAT, probably the least qualified checker you'll ever meet...

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