jimlux wrote:
>
>> As a rough comparison, the springy Aluminum alloys are much like a
>> steel spring. They can be bent, but exceeding the minimum bend
>> radius (which can be quite large) will end up fracturing the
>> material just like bending a flat coiled spring too far will cause
>> it to break or shatter at the bend.
>>
>> With the advent of TIG welding, the ability to weld Aluminum has
>> become far easier. Oxyacetylene welding of Aluminum can be done, but
>> takes practice (One that I never managed to master). Even then it's
>> easy to get a "granular" weld which is not all that uncommon on
>> Aluminum tower cross braces. The reason "Torch welding" is so
>> difficult with Aluminum is the ability of Aluminum to transfer
>> heat. TIG welding creates a lot of heat concentrated in a small
>> area from an electric arc. The welding rod is fed into this arc with
>> the two making the weld relatively easy to control.
>
> Aluminum is difficult to weld for another reason. Unlike steel/iron,
> which turn red/orange well before they get to the melting point,
> aluminum melts at a low enough temperature that you can't tell by
> looking how hot it is. The visual cues are important
That goes along with it's tremendous ability to transfer heat. By the
time the tiny spot you are working on is ready to melt so it the whole
area around it. <:-)) Voice of experience.
> (and with a good TIG welder with foot pedal control, you get good at
> it, at least that's what I'm told.. I'm a terrible welder)
TIG is quite easy to do if you can already stick, or torch weld. (I
don't like the foot switch, but prefer the trigger in the torch handle)
I have a MIG welder (which is great for steel and even easier than stick
welding) and have gone through over three large spools of wire and 3
tanks of cover gas (Argon/CO2) It'll actually do a reasonably good job
of welding aluminum IF you can keep the wire from sticking in the tip.
Too hot and it'll burn off and stick, too cold...same thing, Too fast a
feed..yup. Too slow a feed and it'll burn off. Not that it's difficult
to do<:-))
>
> And, oxidation is a big issue with torch welding.
>
That is actually fairly easy to take care of, by running a reducing
flame. Just let the "feather" extend out a bit beyond the primary cone.
(IOW slightly Oxygen poor or Acetylene rich) The big problem is running
as small a tip as you can while pushing enough through it to melt the
smallest spot. A couple of the guys at the airport can weld two sheets
of thin 6061 and leave a seam that is barely visible. (I'm not one of
them) Of course they always tell me how easy it is to weld Aluminum with
a torch<sigh>
Although it'd be a poor choice of torch, I always wanted to try using a
Hydrogen torch for welding Aluminum. There the flame itself is almost
invisible and man do you use a lot of gas. The actual flame temperature
is notably less than Oxyacetylene, but you can put so much of the stuff
through a small tip you can get a lot of BTU to work with.
OTOH Oxidation can be a problem with TIG as well if you don't get enough
cover gas. That means welding in a protected area or using a LOT of
cover gas. Even MIG welding of steel with even a slight breeze ends up
popping and spitting at you.
73
roger (K8RI)
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