hey Jody here this video is brought to you by my online store at weldmonger.
com let's do it ...today we're welding up some
holes in some .050" (1.2mm) stainless steel. this is a super common task in several
industries like automotive aerospace we're gonna compare the difference
between welding up stainless steel with no backing no argon shielding with
aluminum backing and then with argon shielding so for this first hole I'm not
using anything it's just exposed to air on the back side and when you melt
stainless steel when you penetrate fully through something and it's exposed to
the atmosphere on the back side you get something called sugaring and it's a
non-technical term for excessive oxidation it's granulation and it's bad
it provides all kinds of crevices and nooks and crannies for bacteria to grow
and that's horrible for foodservice or pharmaceutical work but it's also just a
mechanical defect it's just a bunch of stress risers a bunch of pits and it's
just not a good situation also it requires a lot of heat when you got all
that excessive oxidation on the back side it requires a lot more heat just to
flow the metal and to get the thing filled up so I started off with just a
little hole and I've got quite a little plug there before I got it finally
filled up and then that looks like crap
Fido's butt so we're gonna get better than that we're gonna put the next one
against a piece of aluminum backing and what that's going to do is a couple of
things number one it's going to provide a lot of heat sink which is helpful in
stainless steel number two it's going to trap the argon and and kind of provide a
little shielding actually and number three it's going to kind of mold the
penetration it won't let the penetration drop through now copper is even better
than aluminum but a lot of people don't have a chunk of copper laying around I
save little drops of aluminum and copper of all shapes and sizes for a little
task like this but if you don't have it if you don't have a chunk of copper
aluminum is the second best thing so I'm using a little jazzy 10 cup here that
lets me extend the electrode out there where I can get the camera angles that
I need so you can see the arc here but this one's gonna go a whole lot better
I'm gonna be able to keep that heat confined to a really small area and just
kind of it takes a lot less time also to to get the hole filled up with the with
the aluminum backing clamp to the backside here I do a little swirl at the
end as I let off the amperage that's to prevent leaving a little crater I and
you can already see if you had to grind these down or sand these down flush that
second one be a lot easier to do than the first especially on this side you
wouldn't even get all the defects out of the first one this want to take minor
sanding or minor blending and get it right down nice and smooth now let's try
an argon purged box or as we used to call them when I worked for Delta a
backup box now these little devices are very common in aerospace work and it
seems like every aerospace shop has their own sort of design on how they
make them whether they use perforated copper or perforated stainless or even
aluminum but the benefit and copper is that it's so thermally conductive you
can clamp it directly to the backside of something and it won't melt now it's
really easy to make these basically it's just a sheet metal piece that's kind of
broke and welded on the corners a tube that goes the whole link with holes
drilled in the backside where there has to go through this diffuser material and
then you just weld up the perforated copper and sand it off if you want or
just leave it a dual flow meter is usually part of this equation or you
have to have a whole nother whole nother cylinder with another flow meter the
amount of flow that you need is determined by the size of the the
surface area of the backup box and for this one I run at about 20 cfh this this
little box is roughly two inches by three inches you just have to do some
trial and error there so I'm just going to clamp it with a pony clamp to that
backup box and the trick is not to have too much flow coming in there so it's
not fighting against your cup gas if you have too much flow on the backup box it
will disturb that shielding and you'll see you know sometimes you'll see Sparks
and everything it'll create a turbulent area in there but long as you kind of
lick the back of your hand just feel a nice soft flow usually
you're good to go so this hole is about sealed up and
we'll compare it to what we did against that aluminum backing here in just a
second you can see a little difference in the size of the of the plug there so
the aluminum backing definitely drew heat out better and therefore provided a
smaller weld which could be beneficial as far as distortion and things like
that and also if you've got to grind it off it's going to be quicker the main
point here is whether you use aluminum backing or copper backing or argon
shielding it's way better than using nothing