Ice Box Rivets

[RidiculousM]

Hi all, can someone point me in the direction on some solid info such as a book, write up or any literature on how to prepare them? Oven types, temps, time and so on.

Thanks in Advance

Mike

[zilik]

Why? please educate us why?

[Mike S]

To soften them.

http://www.vansairforce.com/communit...ad.php?t=50763

[ralph skorupa]

These are used in commercial and military aircraft and are indeed kept in a refrigerater prior to use. The AD rivets used in RV's and production GA aircraft need not be annealed.

[Pat Falley]

"Ice Box" rivets work nicely on the lighter skins, there is noticeably less force needed to drive them, reducing skin pucker. Some of the nicer RVs were skinned using them. It's for cosmetics, so there is no need to use them on internal structures.

Basically, you are re-heat treating the rivets. Once quenched, it takes some time for them to age harden, and you can take advantage of the fact they are soft for a while. They will age harden back to full strength after a few days, they also work harden when you set them, so they don't lose strength in the process. The important thing is to have a good oven that is accurate and to quickly water quench them. You can store them in the freezer for about a week, after which they are back to normal hardness. I would throw away the ones still in the freezer after a few days and start a fresh batch.

From Sport Aviation:

Heat treating can be accomplished in a small dental oven. The critical temperature not to exceed is 935 degrees, as the rivets will be ruined above this temperature. For small batches--say 100-200 rivets--use a 15 minute 'soaking' period at 850 degrees, followed by an immediate quenching in cold water. Intergranular corrosion, the nemesis of warbird restorers, can be caused by letting too much time elapse before quenching, so be sure to get the rivets from the oven to the water in less than 3 seconds. I like to check a few rivets for overheating just to be on the safe side. This can be done by smashing a few flush head rivets with a hammer on the anvil of your vise. If the rivets got too hot, they'll crack around the thin adge of the head. If this happens, reject the whole batch. Otherwise they're ready for immediate use, and you'll be surprised at how easily they can be driven. It's actually fun! If you don't use all the rivets in a few hours, age hardening can be retarded for up to 2 weeks by storing the rivets in the freezer. The rivets will return to full strength either in the process of driving (work hardening) or by letting them sit for about 6 months (age hardening). Sport Aviation, December 1987, Pg. 54.

[fl-mike]

Originally Posted by ralph skorupa

These are used in commercial and military aircraft and are indeed kept in a refrigerater prior to use. The AD rivets used in RV's and production GA aircraft need not be annealed.

Solution heat treated, not annealed. Different things.

[RidiculousM]

Pat, Mike, and others,

Thanks for the info. Pat that's exactly why I'm interested in going down this road, to reduce that skin pucker in a few areas. I'll checkout that old sport aviation article.

Mike

[xblueh2o]

And shimming from underneath isn't an option?

[rocketbob]

I have a small dental oven retrofitted with a PID controller I use for solution treating rivets. I just make a simple "raft" out of aluminum foil to contain the rivets. Solution treat them at 930 deg. for 30 mins. Pull the raft out with a pair of pliers and drop them into a quart of cold water. Normally I just do enough for the task I am working on. I'm guessing it takes 1/4th the effort to buck rivets which is nice if one is working solo. Look better too.

[Marc Bourget]

The benefit to be gained from “icebox rivets” (2024) is achieved when you alter (expand) the rivet spacing to take advantage of their greater strength. Almost irrelevant in structure designed for 2014.

A dental oven isn’t “solution treating.” Solution treating (rivets). Is achieved by submersing in a heated salt bath.

A dental oven with an accurate controller (+/- 3deg at 900) is good. Quality digital controllers are good for +/-1 deg.

Depening on the temperature, solution treating can achieve two hardening states, “W” temper and full annealing.

One approach is to take the rivets to “W” temper, which is different from full annealing.

Full annealing is achieved at the 935 deg temp.

Skin pucker is a result of harder than necessary rivets. The shaft swells in greater proportion when the rivet is of harder temper.

2017 age hardens at room temperature. Dry Ice, as with the "ice box" rivets, slows the process.

I'd advise a dental oven, treating small batches as you go.