Soldering aluminium sheet metal. Which flux?

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1

I am busy on a car with MIG welded sheet metal from 1050 grade aluminium. My welder advised me to get 35/65 S7 ally welding sticks (tin/lead, 1/4" thick) to fill gaps and followed with the procedure: Wire brush surface. Pre-Heat wider surface area to 170F. Then beyond 500F on the spot while filling with S7 stick.

I figure a flux is needed. I can’t reach my other welder to tell me. Perhaps somebody here knows. I hear about zinc chloride flux and many others…

Suppose the flux has to contain tin and lead as the welding sticks?

2

Can’t help with the flux but you need to use a new stainless steel wire brush otherwise the ally can be come contaminated.

3

Thanks, every little bit helps. I went to get Dowty washer at Hansa Flex and next door happens to be a welding/soldering specialist whom I ignored for years. He had some additional info! I report back.

4

I would also type your exact question into Google and Youtube

There is a remarkable amount of videos on so many specialised tasks these days

(in fact I just did that for you and there is lots of info)

One must be selective, but even reading comments on the Youtube vids can be very illuminating

5

Yes, I shall do that more. Your point exactly: Must be selective. The metal compositions, flux and welding stick seem to be critical. As is temperature and clean surface.

Today’s priority was mechanics and cooling system. Also a manual choke. Different topics…

6

Not sure about your good friend, but the alloy certainly will… :slight_smile:

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