My first attempt at OA welding aluminum

[Timur Aydin]

Hi,

I have finally had the time to try welding two pieces of aluminum using
my OA setup. The pieces were 100x70x6 mm and I tried to butt weld these
pieces.

I had ordered the oerlikon F14 (F LH-1) powdered flux, which I mixed
with rain water so that I had a white cream. I used a stainless steel
wire brush to clean the edges of the aluminum pieces. I then applied the
flux to the weld area. Then I started the flame using a number 3 tip and
adjusted a carburizing flame. But when I started to heat the weld area,
the area quickly got covered with a black coating (carbon?) When I
applied the aluminum rod (covered with flux as well), it melted, but it
ended up being a ball of melted aluminum and didn't adhere to the base
metal. It just kept rolling around the base metal. The base metal also
melted at the joint, but not so much.

Now, one thing I am confused about is whether I was doing aluminum
welding or aluminum brazing. Either one would work for me, but I think
brazing would be easier. Do the plain aluminum rods and the above flux
work for brazing? Should I have adjusted a neutral flame instead? Maybe
my heat was too much and I just burned the flux.

Any help about what could be wrong appreciated...

--
Timur

[Timur Aydin]

I have gone over the information in this link:

http://www.tpub.com/content/construction/14250/css/14250_111.htm

=========================================================
A good example of how aluminum reacts when heated can be seen if
you place a small piece of sheet aluminum on a welding table and heat it
with a neutral flame. Hold the flame perpendicular to the surface of the
sheet and bring the tip of the inner cone almost in contact with the
metal. Observe that almost without warning the metal suddenly melts and
runs away, leav- ing a hole in the sheet. Now repeat the operation with
the torch held at an angle of about 30 degrees to the plane of the
surface. With a little practice, you will be able to melt the surface
metal without forming a hole. Now try moving the flame slowly along the
surface of the sheet, melting a small puddle. Observe how quickly the
puddle solidifies when the flame is removed. Continue this practice
until you are able to control the melting. When you have mastered this,
proceed by practicing actual welding.
=========================================================

Should this exercise be done without applying flux?

--
Timur

[Steve W.]

Adjust the flame to Neutral, you don't want a carburizing flame on
aluminum.
The reason for the troubles you had are the excess carbon from the flame.

--
Steve W.

[fran...123]

"Timur Aydin" <t...@taydin.org> wrote in message
news:TMmdndtWJIhDgb_W...@giganews.com...

maybe this will be some help.

I went to the osh kosh air show thing once and they had some guy doing flame
aluminum welding trying to sell some equipment. It was fast and I recall he
said you clean up after not before like in tig. He had an aerosol can of
magnesium cleaner for mag wheels to clean up with.

I went home and attempted to do the same. Initially I bought some flux It
is probably somewhere. Later I came across a bunch of coated electrodes for
stick welding and now if I do any aluminum welding that is what I use. It
takes a while to get going and then it goes real fast I suppose if you
aren't holding the flame in the right direction it won't go fast in the
right direction. The fumes are awful. If you have ever seen these salesmen
for low temp rods that poke holes in beer cans and fix them with a propane
torch that stuff you kind of have to scrape the rod into the metal to get it
going that might help. I have a box of some eutectic product I think is very
similar but it is hard to have real confidence in it. Maybe if I used flux
I would have more confidence. Since I have tig capability I rarely use
flame however one repair I did makes me think the weld is more flexible for
repeated flexing than tig and 4043.

Fran

[David Billington]

I've not done gas welding of aluminium in awhile but I always recall
the flux was so deliquescent that you could just leave it for a short
while, 30 minutes or so in the UK, and it would absorb enough water from
the atmosphere to dissolve itself and a rinse afterwards to be safe.

Must try it again over the weekend as I have all the stuff still. One
thing I never seemed to have an issue with was seeing the weld, I recall
the flux went water clear when upto temperature and I never had problems
with glare from the flux when using normal goggles.

Regarding aluminium brazing, I think 4047 alloy is suitable for this
when a higher melting point parent metal is used. The 4047 alloy being a
eutectic composition, or near, and melting significantly below many
common aluminium alloys that you might want to join.