soldering aluminum wire

[Nayov]

How do I solder a piece of thin aluminum wire to a terminal that comes from the slip ring to a generator rotor?

I have a Champion generator, with less than 1 hour run time and a broken wire that feeds the terminal to one of the slip rings on the rotor. Rather than use copper, they use aluminum for the windings (cheap!). Still under warranty but I lost the receipt

Moving on.

I have it all apart on my kitchen floor. I want to repair it, or at least try to, and as last resort before using it as a $300 boat anchor.

The strand really is very thin. Will it hold up to the heat of a soldering iron? Also, the wire has a very thin layer of insulation that I'm afraid will break the wire if I try to strip it. Will the heat of the soldering melt off the insulation adequately to make a good contact?

 

[yonyon]

The wire will be fine with the heat. It won't melt at any lower a temperature than if it were a heavy gage wire. You do need to get the insulation off of it.

 

[Cujet]

I did have some success using lead based solder and common rosin flux to solder aluminum wire to copper terminals. Years ago....

The "secret" is to clean the aluminum wire with something like scotch-brite, then scrape the aluminum wire while a blob of solder/flux is on it and covering it, and it's very hot. The scraping removes the aluminum oxide coating (every piece of aluminum ever made has an aluminum oxide surface)(this is due to the INSTANT aluminum/oxygen reaction in the atmosphere)

If you use great care, scrape with something like a razor or xacto (hot, of course) (or even scrape with the sharp tip of the soldering iron) and have it covered in solder/flux, the lead based solder will stick only where the scrape happened. Then, shake it off and you will clearly see the "tinned" sections.

You can solder to these tinned sections. The more of them, the better.

 

[Nayov]

Thanks for the tips.

My biggest challenge is getting the insulation off. I just don't think it would survive a sanding job. Maybe melt it off with the soldering iron first? I'll probably end up using surgical skills I didn't know I had to somehow abrade it off.

 

[Cujet]

Remember that the wire must be scraped clean WITH the solder already covering the aluminum. That shields it from the atmosphere.

 

[Chris142]

We weld aluminum with a rod and torch. Can you use a crimp on connector instead?

 

[spackard]

Are you positive it's aluminum? You're making me picture 30awg wire, and what's the point of going aluminum at that gauge?

If it's magnet wire, omeone suggests putting the wire on top of an aspirin tablet, then holding the hot tip to the top of the wire/aspirin sandwich.

Wikipedia claims newer magnet wire insulation is made to burn back with a hot iron and solder. YMMV.

 

[Nayov]

Originally Posted By: Cujet
Remember that the wire must be scraped clean WITH the solder already covering the aluminum. That shields it from the atmosphere.


Is it possible that the "insulation" is actually a type of rosin material and should be left on while soldering?
It's not traditional plastic insulation, but a brittle caramel colored material. If so, this would prevent the problem of aluminum oxidizing due to expose to air.

 

[Rick in PA]

Originally Posted By: Nayov
Originally Posted By: Cujet
Remember that the wire must be scraped clean WITH the solder already covering the aluminum. That shields it from the atmosphere.


Is it possible that the "insulation" is actually a type of rosin material and should be left on while soldering?
It's not traditional plastic insulation, but a brittle caramel colored material. If so, this would prevent the problem of aluminum oxidizing due to expose to air.


Interesting point. The insulation is probably an enamel, but some enamels are designed to melt off when the heat of soldering is applied. Perhaps try and see if the insulation melts off before soldering.

Another thought, aluminum is a good conductor of heat. It may need a substantial heat source to bring it up to temperature. I'd try one of the old style soldering guns, they had a fairy decent wattage rating.