×
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

Heat treat AD rivets

Heat treat AD rivets

Heat treat AD rivets

(OP)
Recently heard one of our customers heat treat AD rivets to about 200 F for one hour prior to installation so they drive easier. As a structural repair tech and current instructor I have never heard of this practice. My concern is they are annealing the rivets and they will never handle the design loads. I told them it is unnaproved process they are using. At least leave the rivets to age harden again, and if still soft they are screwing up big time. I would appreciate some feedback from the engineer group on an explaination on why this process is acceptable or not.

Thank, Rob

RE: Heat treat AD rivets

this sounds really odd ... AD rivets should be pretty easy to drive. I agree that this is an unapproved procedure, unless they have test data (yeah, right !) although 200degF probably isn't enough to anneal the rivet material. Will (Taylor) can give us chapter and verse !

another day in paradise, or is paradise one day closer ?

RE: Heat treat AD rivets

Rob130... I thought I'd heard every conceiveable rivet heat-treat 'scheme' ... but this one is a real head-scratcher.

I totally agree with RB1957 in every aspect and can only add the following comments...

Baking AD rivets [any size] at 200F for 1-hour will have no discernable metallurgical effect on these parts what-so-ever... hence no value... but, thank God, no likely harm either [metallurgical or finish].

Rob130... Any way to find-out WHY Your customer is doing this operation? Curiosity is killing me. I suspect that there is a "wives tale" at work here; and most-certainly no valid/tested process spec.

NOTE.
I've had several friends in the fastener business, who've tested solid rivet driving forces [bucked or squeezed] VS deformability and factors such as cracking or chipping. This was a high priority from a production and quality perspective. These guys noted that when significant force variations or quality discrepancies were noted, then there was a fundamental issue with the rivet alloy or basic heat-treatment.

Regards, Wil Taylor

Trust Me! I'm an engineer!

Trust - But Verify!

We believe to be true what we prefer to be true.

For those who believe, no proof is required; for those who cannot believe, no proof is possible.

Unfortunately, in science what You 'believe' is irrelevant – "Orion"

RE: Heat treat AD rivets

(OP)
I agree with both of you guys. Their stated purpose of the heating is "they drive easier" which is crazy. Over driving was always the problem I encountered.

I do not want to disparage a particular customer re:Country Air Force, but they are notorious for over thinking the C-130 and thinking they are smarter than the dolts who designed the plane and wrote the manuals. Funny thing was when I started training them they were looking for validation of some of their repair designs and procedures. Seems like a particular Lockheed Service Center was continually charging them to undo repairs they had accomplished at the squadron level. After learning the SRM they realized that Service Center was right. This was quite a few years ago and I thought I had broken them of bad habits and now this rivet thing pops up!

Some amplifying info I picked up from them. They are heat treating the AD rivet to the same spec as DD rivets, quench then drive. Not sure of their quality control or detrimental affect this would have on an AD rivet. They are a couple of young guys who know just enough to be dangerous and they like to experiment.

I'm in Japan right now so pardon the delays.

RE: Heat treat AD rivets

that sounds effing bad ... no-one, No-one, in the industry does this. Do you think Everyone else is as dumb as door posts ? If they do think this is a better process, then qualify it; maybe even trade-mark it ?

possibly the other way to look at it is are they creating a DD type rivet ? with the quench, i don't think so, but i'll let Will lay in.

another day in paradise, or is paradise one day closer ?

RE: Heat treat AD rivets

Rob130... Are You at DNA?
----------------
THIS IS AN AIRWORTHIENESS EMERGENGY.

Re-heat-treating AD rivets was discussed ~10 years ago. VERY BAD IDEA, in theory and practice... especially when done by the techs who would attempt this non-standard process. http://www.eng-tips.com/viewthread.cfm?qid=103368

This process has destroyed the corrosion protective finish on the AD rivets! Most have chemical conversion coating, which will oxidize [disappear] and which likely contaminate/damage the rivet alloy surface. Clear anodize is the only finish that will survive the solution heat treat process. Anodize is applied to all DDs. Anodize is applied to SOME Ds which can be re-heat-treated [bucked in the -W temper].

Situation will be aggravated [temper/strength fail] if AD rivets are heat treated per AMS2770 or AMS-H-6088 per DD [2024] rivet processes... due to differeing SHT soak temperatures.

What troubles me most is that techs who 'think heat-treating ADs is acceptable', generally fail to grasp how important every aspect of the "conventional riveting" and "ice-box-riveting" process is to obtain the appropriate strength/toughness/swell/etc of the simple solid driven aluminum alloy rivet!

Murphy is alive and well...



Regards, Wil Taylor

Trust Me! I'm an engineer!

Trust - But Verify!

We believe to be true what we prefer to be true.

For those who believe, no proof is required; for those who cannot believe, no proof is possible.

Unfortunately, in science what You 'believe' is irrelevant – "Orion"

RE: Heat treat AD rivets

(OP)
Will. I agree with you in all regards. Thanks to you all I can give them engineering feed back. I said I was in Japan but it's not them. I am relaying this info from my colleague who is covering my classes back in Tampa. I am not at DNA. I wotk for CAE USA in Tampa. We train C-130 aircrew and technicians from many countries and commercial operators. I am a retired USCG metalsmith/flight engieer.

I am dumb struck that they would attempt this. If you pm me I can divulge the customer but for obvious reasons I want them to remain anonymous.

Thanks to all for feedback.

RE: Heat treat AD rivets

As a structural/stress engineer I can say that the rivets must be removed and replaced immediately. I would consider the rivets as altered hardware. AD rivets should never be hard to drive. Try using a squeeze. If that is not an option then the equipment being used must be reviewed to see if it is acceptable.

RE: Heat treat AD rivets

I also agree, AD rivets are not hard to be driven, and we have never heat treated them as well! This is dangerous and the repair should not be approved by the authority!

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