Subject: Aluminum brazing

From: [email-masked] (Alan Frisbie)
Date: 22 Jul 96 20:59:47 PDT

I need some advice about welding/brazing aluminum.

The aluminum radiator for the air conditioner in my old car
sprung a leak (an adjacent sharp-edged part had come loose
and rubbed a groove in it).   Since I don't have a TIG machine
yet, I decided to try aluminum brazing.   My instructor from
30 years ago had made it look easy.   However, my current
instructor is on vacation so I had to go it alone.

I picked up a package of Forney "Easy Flo" aluminum brazing
rods.   The instructions on the package say that no flux is
needed.   It says that you just heat the part until you can
melt the rod on it without the flame, rub it in to tin the
part, scratch the surface under heat to work it into the
pores, then melt in enough rod to fill the joint.

Fortunately, I had enough forsight to practice on some scrap
first.   No matter what I did, I could not get the rod to
join with the base part.   Usually I wound up heating the
part so much that it melted in half.

Realizing that I was not skilled enough to fix the radiator,
I took it to a welding shop where they TIG welded it for $20
(a great bargain).

However, I would still like to know what I was doing wrong.
What is the correct technique (and rod) to use for brazing
aluminum?

--  Alan E. Frisbie               [email-masked]
--  Flying Disk Systems, Inc.
--  4759 Round Top Drive          (213) 256-2575 (voice)
--  Los Angeles, CA 90065         (213) 258-3585 (FAX)

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From: [email-masked] (James P. Riser)
Date: 23 Jul 1996 15:48:59 GMT

In article <[email-masked]>, [email-masked]

> --  Los Angeles, CA 90065         (213) 258-3585 (FAX)

Alan;
I was at a welding demo a few months ago and a guy was welding aluminum
with "190 rod" and a blue powdered flux.  It did a great job.  The problem
is always that the rod melts at only a few degrees cooler than the base
aluminum.  You really need to use a relatively cool flame and apply the
rod as soon as the flux beads up.  I feel that this flux and rod is much
easier to use than the fluxless type.  It's a good idea to stainless steel
brush parts first to clean the surfaces. The rod comes in two types - one
for flowing out and the other for building up (like for filling holes).  I
hope this helps.  If you get any info from others, please forward it on to
me.  Thanks.
Jim

-- 
James P. Riser
Home page:  http://www.azstarnet.com/~jriser

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From: [email-masked] (Wirdweird1)
Date: 23 Jul 1996 22:46:27 -0400

Practice makes perfect.  We do some aluminum brazing at our shop and only
one person has been able to get the hang of it.  Cleanliness of the
aluminum has a lot to do with success and failure.  Different alloys of
aluminum react differently to the process.  I will check tomorrow with our
brazer and get back to you with more info.

Alan Hall
Alan Hall, [email-masked]

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From: [email-masked] (Stan Malyshev)
Date: 25 Jul 1996 16:15:09 -0700

In article <[email-masked]>,
Al Amaral - SunSoft Engineering <[email-masked]> wrote:
[]
>I picked up a hole in an aluminum oil cooler on my old RX7 years back.
>I brought it to a radiator shop to be fixed and, believe it or not, they
>used some kind of plastic to patch it.  They said that it was too hard
>to try to weld or braze it because the tubing walls were too thin.

I think I recall seeing epoxies with Al filler in the MSC catalog.  The shop
may have used something along those lines.

-S

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From: [email-masked] (Al Amaral - SunSoft Engineering)
Date: 25 Jul 1996 19:06:14 GMT

In article <[email-masked]> [email-masked] (Alan Frisbie) writes:
}I need some advice about welding/brazing aluminum.
}
}The aluminum radiator for the air conditioner in my old car
}sprung a leak (an adjacent sharp-edged part had come loose
}and rubbed a groove in it).   Since I don't have a TIG machine
}yet, I decided to try aluminum brazing.
}
}Fortunately, I had enough forsight to practice on some scrap
}first.   No matter what I did, I could not get the rod to
}join with the base part.   Usually I wound up heating the
}part so much that it melted in half.

FWIW:

I was skeptical, but with the difference in price between a new oil cooler
and their plastic patch repair I figured it was worth a shot...

I never had a problem with it...

--Al Amaral--
-- 
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Al Amaral				  [email-masked]
"G'day, and welcome to All Things Delta.  If it's not Delta, IT'S CRAP!" 
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