proper grinding of tungsten?
Jeff Nelson
importance of grinding in the direction of the point when dressing tungsten
electrodes. My welding instructor at the local community college is quite
adamant that it is unnecessary. He claims that none of the journeyman
welders that he encounters use the method and therefore it isn't valid. This
guy has been teaching for a long time and has been around. He can certainly
make a pretty bead. There is no question about his ability to weld. I
however have a very hard time welding. (Nothing a few hundred hours of seat
time wouldn't help, I'm sure.) I would like every advantage, however. I
struggle enough just trying to see the puddle let alone conpensate for some
other behavior that an experienced welder might shrug off.
So, what is the considered opinion of the group as to the importance of the
direction of the grind? Thanks!
John Noon
Aligning the grooves along the axis of the tungsten;
The current flow along wires and tungsten is along the outer surface (mostly
or totally? faded memory at work here). So grooves along the axis will have
less resistance to current flow and provide you with an arc that is more
stable.
Grooves across the axis increase the resistance to current flow, as well as
providing multiple locations for an arc to form, giving you a rougher arc.
From my very limited experience with TIG welding I have noticed a difference
but it is not something that may jump out at you.
If I am way off please feel free to jump all over it.
Thank You
John Noon
"Jeff Nelson" <jeff_...@agilent.com> wrote in message
news:10306399...@cswreg.cos.agilent.com...
Gary Coffman
>The current flow along wires and tungsten is along the outer surface (mostly
>or totally? faded memory at work here). So grooves along the axis will have
>less resistance to current flow and provide you with an arc that is more
>stable.
>Grooves across the axis increase the resistance to current flow, as well as
>providing multiple locations for an arc to form, giving you a rougher arc.
DC passes through the entire cross section of the conductor. But HF current
flow is almost entirely a surface phenomena because of skin effect. So a
preferred grinding direction has the most effect when you're using continuous
HF (mostly when AC welding).
Gary
John Noon
I new my memory was coming up short just not where. Never even thought of DC
or HF current and with TIG that would be important.
This also explains why I would notice a difference in grinding method only
part of the time. Someone may ask why I was grinding my tungsten's wrong, I
was trying to determine what differences it would create in the finished
weld. This is what happens when you get bored, I even experimented with
asymmetrical grinding to see if it would be possible to aim the arc off to
one side.
John Noon
"Gary Coffman" <ke...@bellsouth.net> wrote in message
news:aunsmu828orsai1mj...@4ax.com...
David Todtman
> asymmetrical grinding to see if it would be possible to aim the arc off to
> one side.
beginner) try to make the tip symmetrical but sometimes get close but not
right on the button. I cannot discern a difference in my welds (all MS so
far).
Ciao,
David Todtman
Ernie Leimkuhler
"Jeff Nelson" <jeff_...@agilent.com> wrote:
You will find that if you grind the tungsten, with all grind scratch marks in
line with the tungsten, that you will get better control, and easier starts,
especially at low amperages or on an older TIG machine with iffy High freq.
Personally I prefer to point the tungsten up, rather than down, so no burr forms
at the tip of the tungsten.
Give yourself every advantage possible.
Go here for the full write up.
Pro-Fusion - Tungsten Data http://www.Pro-FusionOnline.com/tungsten/
There are a lot of bad habits in industry because some guy figured out that he
"can get away with it".
He then tells his buddies and pretty soon they all think they "can get away
with it ".
That does not make it good practice or worth emulating.
Trust the experts here.
Welding engineers spend a long time coming up with stuff, and it is not hooey.
Some welding engineers actually know what they are talking about.
--
--
The difference between genius and stupidity is that genius has it's limits....
(Albert Einstein)
John Noon
Tried tapers offset so one side was straight with both flat and conical
profiles.
Smaller equipment is far more practical when trying to get into tight areas.
Which explains why something like this is never mentioned in books.
John
"David Todtman" <dtodtmanR...@shaw.ca> wrote in message
news:KMvb9.229765$f05.12...@news1.calgary.shaw.ca...
Wyll Smith
grandfather. i, my shop holds several certs, aws , and a couple mil certs.it
makes no difference how you grind your tungsten. im sure the people that have
gone to school and know the theory will tell you how and why it should be done.
i grind my tungsten on an eighty grit belt. the same belts we use to clean
material. steel, stainless or aluminum. in fact, i was making some gorgeous
aluminum signs for the kimmel center (new performance/concert hall here in
philly), and i used which ever grinder was open at the time.
my point is, dont worry so much about how you grind your tungsten, concentrate
on the actual welding.
R Duncan
Eric D
> direction of the grind? Thanks!
Jeff,
You have asked something that you will get a number of suggestions as
to the right way, what matters and what doesn't. Some of this you
will have to figure out yourself. With that said, I will give you my
thoughts. I believe in doing everything the best I can. I take great
pain in doing the best grind I can on every tungsten I prepare. Most
of the welds I do have something to do with aircraft. People fly in
them and they fly over many more. It has to do with getting the best
out of everything you do. If you shortchange any part of your work
then you have not done the best you can. If you are working on things
that do not put anyone at risk then do what you want, however, if
someone's safety depends on your work then be sure it is the best you
can do.
Just my two cents worth!
Eric D
Pat Molvik
the tip of the tungsten during welding due to thermally induced fatigue. This
tungsten inclusion creates a stress riser within the weld that could contribute
to weld failure sometime in the future. If your weld will undergo a RT before
acceptance the tungsten will show up on the film as a white spot flaw and may be
rejected.
Pat