View Full Version : DC TIG on Alum ????
cnitrofumes
05-08-2008, 06:49 PM
What's the setup for DC Tig welding of alum. I've done quite a bit of AC High freq welding but never DC. A lot of the stuff I weld is repairs on racing engines...kind of dirty stuff. Will DC float the crap to the top like AC ??? Sometimes between cheap castings and years of oily usage It's almost impossible to get a clean weld even with all the pre-cleaning and such.
weldgault
05-08-2008, 07:06 PM
You would have to use DCEP for Aluminum and that current will Distroy your Tungsten. ACHF or MIG DCEP for aluminum. John
Winnfield
05-09-2008, 12:45 AM
DCEN is the way to go, but you will need lab grade helium as your shielding gas. I didn't think this would work very well, until Pangea on this board suggested it a while back, and I think he is a very experienced professional, if I am not mistaken. I tried it with some ordinary helium with better-than acceptable results, and now I see no reason to use AC again if I can get some lab-grade gas.
Look here: http://www.hobartwelders.com/weldtalk/showthread.php?t=30217
hankj
05-09-2008, 12:57 AM
The original "Heliarc" ( a trade mark) process WAS DC, with, as mentioned, Helium (hence Heliarc) as the shielding gas. It was very successful.
The GMAW process may be the most evolved of all of the accepted portable welding processes, IMHO.
Just an opinion, brothers!
Hank
10Speed
05-09-2008, 05:43 AM
The original "Heliarc" ( a trade mark) process WAS DC, with, as mentioned, Helium (hence Heliarc) as the shielding gas. It was very successful.
The GMAW process may be the most evolved of all of the accepted portable welding processes, IMHO.
What thickness of aluminum can be welded with aluminum with helium as the shielding gas. Is the only problem with using DC on aluminum is a chance of blowing through the aluminum more easily. I would like to know b/c I don't weld al that often but have come across a lot of like new Maxstar 200's.
Thanks
10speed
whateg0
05-09-2008, 12:31 PM
...Is the only problem with using DC on aluminum...
Short version...
With DC, you are either going to be getting good penetration or good cleaning. With AC you get a little of each.
Dave
weldgault
05-10-2008, 08:05 AM
I have never heard anyone recommend DC on Aluminum. Not Union Carbide, Linde, L-Tec. or ESAB. I hope there is a challenge to this. John
cnitrofumes
05-10-2008, 05:41 PM
I heard about it...tried it briefly with straight Argon....DCEN.....ended up with a black, lousy looking bead with no penetration. That's why I asked about the setup. Kind of resembled a bad Mig alum bead....ropey and black.
Winnfield
05-10-2008, 11:19 PM
I heard about it...tried it briefly with straight Argon....DCEN.....ended up with a black, lousy looking bead with no penetration. That's why I asked about the setup. Kind of resembled a bad Mig alum bead....ropey and black.
Thats what you'll get if you don't use Helium - thats an important detail.
Rocky D
05-11-2008, 01:12 AM
I have never heard anyone recommend DC on Aluminum. Not Union Carbide, Linde, L-Tec. or ESAB. I hope there is a challenge to this. John
DC straight with helium produces high heat and greater penetration, and is used on heavy weldments...should be used on 3/8" and above.
SundownIII
05-11-2008, 08:03 PM
I fully agree with Rocky's description of welding with DC electrode neg and helium gas. It is an extremely hot weld used almost exclusively for heavy weldments.
While Pangea clearly states that he is a rocket ship welder (welded on the shuttle), and claims to hold many certs in tig welding, I did find his posting on the effect of Hi-freq (cleaning) to be very confusing to the inexperienced tig welder.(another posting)
I would be very interested in hearing how Pangea would set up (amps, tungsten (size, type), cup, and gas) to weld say, an 1/8" butt weld with DC Neg and helium.
cnitrofumes
05-12-2008, 08:09 PM
SOOO.. is hi freq necessary with DCEN on Alum. ???? I was thinking this would be the way to go on these heavy castings. I preheat the whole engine block with the patches jigged right into place. I'm thinking if I can get more heat and penetration with DC it would make for less weld time and less chance for distortion.
I was also toying with the Idea of a spoolgun with my CV supply for real ease and speed. Would the Helium and DCEN apply for this process as well ????
Rocky D
05-12-2008, 08:58 PM
Let's put this in perspective...DCEN on aluminum has all but become obsolete due to Aluminum MIG. It's rarely, if ever done anymore. MIG is the way to go, and with argon, not helium. That said, engine blocks can be welded quite satisfactorily with AC TIG.
SundownIII
05-12-2008, 09:32 PM
Rocky--Agree wholeheartedly.
Seems that Pangea has started a "dc tig movement" for welding aluminum. Can't, for the life of me, understand where he's coming from. His comments in another post about the effect of hi-freq cleaning the weld at 60,000 cyc/sec left me scratching my head.
cnitrofumes,
Hi-freq is not needed for dc tig welding, except to start the arc. Most people use lift-arc or scratch start on steel. Hi-freq has no "cleaning effect" on the weld. Hi-freq is used in AC Tig welding to maintain an arc as the wave cycles between DC+ and DC-. The older tig welders (Miller 330 A/BP, Dialarc, Cybertig, etc) were pre-squarewave machines. Hi-freq was used to prevent the arc from extinguishing with each cycle change. The later Tig machines employed a squarewave design and made the transition much faster, but still required hi-freq. The newest, advanced squarewave machines (Dynasty, TA, etc) use inverter technology and make the transition very rapidly and rely on hi-freq to start the arc only.
I'm still waiting for Pangea to chime in with a complete description, to include setup, of how he would weld, let's say a T-joint with 1/8" or 1/4" material. I can't find any reference in any of the tig manuals I have. I'd also like to know where to obtain that "lab grade Helium" he constantly makes reference to.
I've only been tig welding aluminum for a little over 40 years (was welding our aluminum fuel tanks for our race boats in '65) so I guess I've been doing it wrong for a long time.
Pangea
05-13-2008, 05:50 AM
Wow. Looks like I have been "called out into the street" over a practice that has been used over 25 years in aerospace and is still used today. In fact, if I wasn't going to an overhead crane training class today, I'd be welding some DCEN on some .250 2195 aluminum. The AREA/Orion will be made out of 2195 and a little 2219 also. These will be friction stir welded and we hope to have -0- fusion welds on the whole project. The only fusion welds will be start/stop tabs.
DCEN. I have welded .125 with DCEN on 2195 and 2219 for certs and on flight hardware. Most of the DCEN is on .250 and .375 as that is what the rocket is made of. The .125 is on fittings for penetrations to the domes. Using a #7 cup and 2% thoriated tungsten, set your machine amperage to about 160. You have to have the good helium. Our bottles are laboratory grade on them because that is what is called for on the WPS. Grind your tungsten to a point, then flatten the tip a little. Weld it like you would steel. You wont see a puddle. you just have to know when to add your wire.
I've tried to weld DCEN on castings and it doesn't like it at all. The castings that I tried it on were outboard motor parts. Finally had to AC those parts. All of my welding on boat motor castings and chainsaw castings(magnesium) are done AC.
As far as having been accused of starting a DC movement on aluminum, somebody is giving me way too much credit. That was started around the time I was born I think.(1958) Maybe it was done in my honor? Pangea, messiah of DCEN? Nah.
vicegrip
05-13-2008, 12:14 PM
Wow. Looks like I have been "called out into the street" over a practice that has been used over 25 years in aerospace and is still used today. .................................................
As far as having been accused of starting a DC movement on aluminum, somebody is giving me way too much credit. That was started around the time I was born I think.(1958) Maybe it was done in my honor? Pangea, messiah of DCEN? Nah.
I have neither the skill or patience for DCEN on aluminum.
BUT the pro's I hang with, would validate his assertions,
and throw their lot in with his.....but that they don't do forums.
Open minds, and comprehention RULE every time.
vg
Hey guys what's up? I have been in the industry for some time now and
started my own shop here beside my home in Martinez CA two years ago.
I'm 60 years old and do a lot of production job shop welding but now and then I find myself involved with someones proto type project. I googled my question
and it brought me here to your site, so I decided to get aboard with you guys and maybe make my life a little easier with all these other experienced fellas
on here to pick brains once in a while. Plus maybe share some of my knowledge in the process. There isn't too many of my welder friends left anymore to share info with so I sometimes have to guess or do a lot of testing
to get the results I'm looking for...I have used the straight DC helium (Tig)
method of welding aluminum many times, mostly for heavy thickness applications. I use grade 5 helium or what gas companies call ultra high grade
Sometimes I even blend some argon in with it (mixer) which mellows it out a bit. Making the welding eaiser to control on thinner material. The aluminum
must be extremely clean and a weld prep machined into the weld area helps
also...Do any of you guys ever use the helium/argon mix like I mentioned?
BC
Wow. Looks like I have been "called out into the street" over a practice that has been used over 25 years in aerospace and is still used today. In fact, if I wasn't going to an overhead crane training class today, I'd be welding some DCEN on some .250 2195 aluminum. The AREA/Orion will be made out of 2195 and a little 2219 also. These will be friction stir welded and we hope to have -0- fusion welds on the whole project. The only fusion welds will be start/stop tabs.
DCEN. I have welded .125 with DCEN on 2195 and 2219 for certs and on flight hardware. Most of the DCEN is on .250 and .375 as that is what the rocket is made of. The .125 is on fittings for penetrations to the domes. Using a #7 cup and 2% thoriated tungsten, set your machine amperage to about 160. You have to have the good helium. Our bottles are laboratory grade on them because that is what is called for on the WPS. Grind your tungsten to a point, then flatten the tip a little. Weld it like you would steel. You wont see a puddle. you just have to know when to add your wire.
I've tried to weld DCEN on castings and it doesn't like it at all. The castings that I tried it on were outboard motor parts. Finally had to AC those parts. All of my welding on boat motor castings and chainsaw castings(magnesium) are done AC.
As far as having been accused of starting a DC movement on aluminum, somebody is giving me way too much credit. That was started around the time I was born I think.(1958) Maybe it was done in my honor? Pangea, messiah of DCEN? Nah.
Are you using a Gas lens...and what size tungsten? Thanks BC
Does anyone ever answer your questions here?
Rocky D
06-18-2008, 10:13 AM
...Plus maybe share some of my knowledge in the process. There isn't too many of my welder friends left anymore to share info with so I sometimes have to guess or do a lot of testing
to get the results I'm looking for...I have used the straight DC helium (Tig)
method of welding aluminum many times, mostly for heavy thickness applications. I use grade 5 helium or what gas companies call ultra high grade
Sometimes I even blend some argon in with it (mixer) which mellows it out a bit. Making the welding eaiser to control on thinner material. The aluminum
must be extremely clean and a weld prep machined into the weld area helps
also...Do any of you guys ever use the helium/argon mix like I mentioned?
BC
You're the first guy that I have ever heard of that does DC aluminum in a job shop. I also have never known it to be used on thin material, like you say, so I'm all ears...could ya elaborate on the params you use, and for what thicknesses?
Are you using a Gas lens...and what size tungsten? Thanks BC
To qualify, I've been in this business half a century, and have always used a gas lens with DC TIG...AC HF tends to eat them up, so that's when the collet body is needed.
Pangea has just got a job as a lead weldor in a FSW project, so He's got his hands full, ...is prolly why he's not answering....I didn't want you to think we here are dissing ya, so I jumped in.
LOL, That's cool...Being the "New Kid" I probably shouldn't have shook the fence....I picked up the Straight DC alum deal when at a local semi-conductor company. They incorporated 96 CNC stations and I was the only tig station..
So the machinists had me making tomb stones for holding their parts all the time. It would be thick aluminum (1 inch) and there was no way I could pre-
heat it so AC was out...I had pretty good success with the Straight DC with
grade 5 helium in welding that thick aluminum.....It didn't have to be "Show car
welds" just stick it together strong enough to hold for that run of parts.
As time went on I decided to try the DC on small aluminum parts...Especially
the ones that needed good pen for High Vac situations....It worked great,
Not always as pretty as AC but very good pen. It definitely is something that takes practice since it is totally different from what we are used to.( being OLD
guys) with old habits LOL I have a job out there in the shop right now that I'm going to weld up with DC. I'll post some pics...
Thanks for the come back, BC
NMWelds
06-18-2008, 02:50 PM
I really enjoy learning all the different ways there are to do one job. Learning that you CAN weld alum. with DC when set correctly is news to me.
I would like to ask you though, is that how you learned to weld thicker alum parts and thats why you TIG with DC or is there an advantage to it over using MIG? I've never run into THICK aluminum but if I do I'm sure I could MIG weld it better than TIG. Should I practice this on some thicker pieces just in case?
Pangea
06-18-2008, 05:25 PM
I use a gas lens; because that's what my WPS calls for, and 3/32" 2% thoriated tungsten. Never heard of mixing argon with helium but what ever you can get by with within your spec, go for it. Unlimited thickness aluminum can be welded DCEN just like ferrous metals, using multi pass welds of course. The thinest that I have used DCEN on is 1/8".
Sorry for not posting sooner. I have been concentrating on my work and it is very demanding.
You use the same set up that I use as far as the tungsten and gas lens 7 cup
When I get really thick plates I go to the larger torch (5/32 ) that can handle
higher amp settings...(as you already know) I would like to see some of your
projects at work...Must be challenging.. I know that the copper welding was really different ( I worked in the clean room at Semens building accelerators
for the cancer treatment machines. Very rewarding work, till the Germans
took everything back to Germany and we were out of a job....They were in Concord for 26 years and when Varian took the lead in technology they bailed.
Hated to see that happen..But being a wise old man I survived...I was telling Rocky I had a couple aluminum jobs today in the shop and I would get some pics. So check back later and by then I would have them uploaded to my
web storage site and I'll get them over here..
Later BC
http://im1.shutterfly.com/procserv/47b8d839b3127ccec4304902794200000026100AcNGjdq4ct2 IPbz4Qhttp://im1.shutterfly.com/procserv/47b8d839b3127ccec430928ab80f00000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec4313aac983100000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec430eef7397c00000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec430164739b000000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec430883a398200000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec43198bb987700000026100AcNGjdq4ct2 IPbz4Q
http://im1.shutterfly.com/procserv/47b8d839b3127ccec431f5c9d8ab00000026100AcNGjdq4ct2 IPbz4Q
I like these kind of small jobs, thet get machined all over so show car welds aren't necessary..
Just good pen and get er done....
http://im1.shutterfly.com/procserv/47b8d839b3127ccec4303f74f83f00000026100AcNGjdq4ct2 IPbz4Q
I used AC and alumix gas on this Camber support, again no show car welds
weld preps on most joints let them grind the welds smooth....Het it pays the
bills ....LOL
BC
DC straight with helium produces high heat and greater penetration, and is used on heavy weldments...should be used on 3/8" and above.
Here here use ACHF for thinner aluminum.
Pangea
06-18-2008, 09:13 PM
B_C, those are some good looking welds. I usually backtrack and terminate on the weld to keep from developing crater cracks but since you will grind those flush, it won't matter. People that have never welded DCEN get all worried when they see all of that black smut. It brushes right off though. On this 2195 the smut will take your breath away and give you coughing fits for about 10 minutes if you catch the slightest whiff of it. It's nothing like any other aluminum that you've ever welded. You can be laying a bead that you think will bring tears to an instructors eyes, then lift your shield and there will be a crack for the entire length of the weld. Then you can put down one that you are ashamed of for fear of cold lap and it passes everything. Dye pen, UT, X-Ray. This stuff will crack on a repair over and over but then you change direction of the weld and it heals up.:confused: Crazy stuff. I have been welding it for about 4 years total.
I have had the crack down the center with 5356 on 1/2 " thick material.....
even if I pre heated....very weird...then switched to 4043 and welded perfect..
Go figure? This last little cradle part I made is going to be black anodized
tomorrow and I didn't use 5356....:eek: They will probably complain about the different color of the welds...Oh well it only holds a electronic part:D
So you never blended argon with helium before? How about with AC making your own "Alumix blends" When I'm out of Alumix I sometimes add helium to the argon line to heat things up a bit...works great...
BC
I have been hearing this story for years and wonder now that I'm on the
site where the PROs hang out if any of you old timers ever heard the one
about welding aluminum will give you a better chance of getting Alzheimer
disease?
BC
Pangea
06-18-2008, 09:44 PM
I can't mix gasses. If it isn't in my WPS, (Weld Process Specification), it isn't allowed. We are held to very strict requirements and straying from them will cause you to be escorted out of the facility. I've been hearing the stories about alzheimers for decades. Welding aluminum doesn't bother me bother me bother me.:D
I'm getting away from fusion welding for awhile, maybe forever. We are trying to build this next rocket system with 100% Friction Stir process. Longitudinal welds will be Conventional FSW , circumferential welds will be Self Reacting FSW, multi axis welds will be both C-FSW and SR-FSW, and circumferential terminations will be Friction Plug Welds. There may be one fusion weld on a fitting, but we are trying to design that one out.
How much force is required to make a...lets say 1in bar weld to a 1in plate?
or am I not thinking this out right for a fusion weld..:confused:
BC
Craig in Denver
06-18-2008, 11:53 PM
I have been hearing this story for years and wonder now that I'm on the site where the PROs hang out if any of you old timers ever heard the one about welding aluminum will give you a better chance of getting Alzheimer disease?
BCI think the answer to this question lies in your very own signature. :D
And, I'm older than you, 60 going on 13. :p
I understand WPS and rules for work .....but don't you have a shop away from work?
I think the answer to this question lies in your very own signature. :D
And, I'm older than you, 60 going on 13. :p
COOL, lets go get some cardboard boxes and slide down the grass hill...:eek:
Craig in Denver
06-19-2008, 12:02 AM
COOL, lets go get some cardboard boxes and slide down the grass hill...:eek:Can't, ex-motocrosser ('79), need bumps. ;)
What did you ride back then? I was riding this....
http://im1.shutterfly.com/procserv/47b7d701b3127ccec27dc3bc805b00000016100AcNGjdq4ct2 IPbz4Q
Pangea
06-19-2008, 04:37 AM
I understand WPS and rules for work .....but don't you have a shop away from work?
I have a MIG welder at home for my wrought iron work. My Syncrowave was sold off a long time ago and I wish I still had it.
What do you use at work? I really like the way the new Millers weld but
my Lincoln 355 still works pretty good and the little issues it has aren't causing me any problems...Kinda like a woman you just get used to them a deal with it
LOL...BC
platypus20
06-19-2008, 10:45 AM
...How about with AC making your own "Alumix blends" When I'm out of Alumix I sometimes add helium to the argon line to heat things up a bit...works great...BC
I did an aluminum job for a contractor about 3 yrs ago, it was a number of fixtures, made out of 1/4" aluminum angle and plate, it was all tig welded using 75%helium/25% argon, since then I alway use the mix to weld aluminum, if its above 1/8", it just seems to flow easier.
jack
Exactly, plus it leaves less chance for a cold weld joint....I usually go the other direction
75 argon 25 helium but whatever works for the job...Maybe 75 helium and 25 argon with Straight DC I talked about that earlier, on thinner material (aluminum)
BC