Looking for reference material on riveting dissimilar metals

[John Bickham]

I'm working on my aluminum formers. In Bob's EC Jan 2013, he specifies SS pop rivets. I can definitely do that. Are there any known applications of using solid AN426 (flush) rivets when joining aluminum to steel? Well aware of the long "conversations" of the past regarding galvanic corrosion between different metals. Really looking for some documentation or an application where this applies. The solid flush rivets are preferable to me for finished look.

It is not structural, but a permanent fabric joint. The picture is the bottom side of the rear window sill former.

Rear Window Frame (5).JPG

[S Lathrop]

I have struggled with bonding aluminum belly pans to the steel tube frames I build fro race cars. The aluminum is structural to the frame. I now have a system that works well but is a PIA.

I would consider that you use a structural adhesive between the parts. I would prep the aluminum. I my case I have the aluminum anodized. I do rough up the bonding surface on the aluminum before anodizing. The adhesive is generally a lot higher strength in sheer than the rivet. The rivet is there for peal strength in the bond. I bond to bare steel that has been grit blasted. I feel that any finish on the steel is likely to reduce the bonding strength.

When I do the joints, I have rivets every 3/4 inch or less, and in more than a single row. For the application you are considering, I think a small area of adhesive around the rivet itself would worth considering. Maybe a 1/4 diameter or double the rivet diameter. The adhesive might prevent the rivet from loosening and allowing fretting of the bonded materials.

I know that Bob recommends SS rivets, but I have not had good experience with SS rivets. I find they tent to loosen and do not expand to fill the hole as a proper aluminum rivet will. I have had good luck with Avex and Cherry Q rivets for all but the most highly stressed applications. I have used these rivets in aluminum monocoque race cars where the entire structure is riveted and bonded aluminum.

I don't know if this explanation is helpful but it might be something to consider.

[alaskabearhawk]

http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook/media/FAA-8083-30_Ch06.pdf

[John Bickham]

Thanks Paul. That is exactly what I was looking for. I didn't realize those manuals were there. I'm nominating you for "The BearHawk Librarian". Jared has the "Knowledge Base Manager" with the BearHawk Tips and maybe the old google forum one day. Bless you Jared.

S(name?) - you are actually right on track with Bob. In one of my conversations with Bob concerning the aluminum formers, he mentions you could use a "flexible epoxy like they use on the Carbon Cubs". I haven't figured out exactly which epoxy is used on the Carbon Cub but I think the epoxy Mark recommends, T-88, is flexible.

Appreciate the help. Got too much to read now.

[S Lathrop]

I have used Hysol and 3M Scotch Weld adhesives. Both are available from Loctite in the same type dispenser.. Exactly which would be best might take a little study. My experience is with the rigid types. But both brands have flexible adhesives.