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Gluing copper to mild steel ?

AlexO

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Sep 12, 2004
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RSA
Could anybody recommend a good adhesive for gluing copper to steel ? I need to glue 1mm thick 6" dia copper disks on mild steel.
 
Almost any quality epoxy should work. More important is the temperature and environment (wet? oily?) the parts must live in. And surface preparation and cleaning prior to assembly is more critical than getting the exact right adhesive.
 
Almost any quality epoxy should work. More important is the temperature and environment (wet? oily?) the parts must live in. And surface preparation and cleaning prior to assembly is more critical than getting the exact right adhesive.

I can clean everything very well. Must I etch the copper ?
 
You get much better performance if you are able to sand blast both surfaces. Literally 10X the holding power compared to just cleaned smooth surfaces. I've seen Dan Gelbart perform this exact experiment in his 100 ton press with aluminum cylinders glued into holes. The difference is amazing. Maybe you can't mask or blast the surfaces completely but do the best you can.
 
You get much better performance if you are able to sand blast both surfaces. Literally 10X the holding power compared to just cleaned smooth surfaces. I've seen Dan Gelbart perform this exact experiment in his 100 ton press with aluminum cylinders glued into holes. The difference is amazing. Maybe you can't mask or blast the surfaces completely but do the best you can.

Good idea. I can't have any contamination of the copper surf but I'll see if salt for example, won't work.
 
structural 2K acrylic adhesive would be my choice. Not so fussy about cleaniness as epoxy.
 
Hopefully the application will keep the part at a narrow range of temperatures. There is quite a difference in thermal expansion between copper and steel. Copper coefficient is 16-16.7 and steel's is 11-12.5 so bad things can happen if the part heats up or cools down a lot.

metalmagpie
 
What ever you use a light sanding would be a asset to gluing and then no touching the glue area with fingers...
Needing electrical passage solder or brazing needed.. light sanding needed for solder or braze.
A small sliver of silver makes braze flow better..Think braze make +.005 in height..If I remember right

Qt wild bill [Call Loctite and ask them (800) 562-8483 U.S.] good advice...
 
Hopefully the application will keep the part at a narrow range of temperatures. There is quite a difference in thermal expansion between copper and steel. Copper coefficient is 16-16.7 and steel's is 11-12.5 so bad things can happen if the part heats up or cools down a lot.

metalmagpie

Yes, CTE is a good reason to stay with adhesive. I think I would stay with epoxy over acrylic adhesives due to better water resistance, which could be an issue in a lapping machine.
 
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You get much better performance if you are able to sand blast both surfaces. Literally 10X the holding power compared to just cleaned smooth surfaces. I've seen Dan Gelbart perform this exact experiment in his 100 ton press with aluminum cylinders glued into holes. The difference is amazing. Maybe you can't mask or blast the surfaces completely but do the best you can.

Yes, I agree sand blasting will improve adhesion. HOWEVER, sand blasting will warp that copper like a potato chip.
 
Or a toaster oven. I have an old one in my shop with one coil broken. It still heats up enough for soldering. I have done PCBs and some small mechanical parts with it. For one project I combined some large fender washers with some tubular spacers into some steel wire spools.



Soft solder. You can do it in a frying pan.
 
I'm assuming you are trying to lap the copper disks and want to use a steel plate to back them. In that case, you could also use a spray adhesive. 3M has an extensive line of adhesives that may work. Epoxies will hold the parts together, however if you plan on removing the copper from the steel backing it will probably not survive. Solder will allow the copper to be removed, but the solder itself may prove difficult to get off the copper.
 
Now, that sounds interesting. How do I make sure the two surfaces touch one each other, stay flat ?

Clean and tin both surfaces. Clamp them gently, heat til the excess solder squishes out.

Stay flat? That wasn't part of the original problem. If both steel and copper are thin, there will be some dishing because of different thermal expansion rates. But if the steel is thick and the copper thin there will be little distortion. If flat is important I suggest you provide stock allowance for post-solder machining.

Soft solder takes place at 400 to 550 F depending on solder alloy. 2500 to 4000 PSI bond strength, again depending on solder alloy. I suggest a 95+% tin, 3% silver 0.8% copper alloy as being stronger, having better wetting, and lowest melting temperature of all but 37% tin 63%lead solder. Use the right flux.
 








 
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