How best to weld aluminum

By guy

Date 02-11-2001 06:24

[deleted]

By John H. UK (*)

Date 02-11-2001 13:24

Hi Chuck,
Remember as well that if you're going into TIG welding aluminium, and like the last post I would say it's proberly your best bet, don't forget to look for TIG welders that support AC High Frequency (HF) current output. You'll notice most MIG sets are DC and cheaper stick, I've been lead to believe, are AC. I remember being told that the humming of the cheaper stick sets AC transformer gave them the nick name Buzz Boxes. Many people would choose to use a MIG only if pushed on non critical work, even though the manfactures will tell you they have better than robotic TIG results on Al. With something like your intakes that could be subjected to quite a lot of physical strain you only really can choose an AC TIG set (GMAW in the US, Gas Metal Arc Welding). AC TIG sets will have a DC option as well and you can even run your stick electrode off it if you want to (Much better stick control). TIG gives you emense amounts of control over the arc and filler and when I first saw some welds done by a TIG I really did think they had been done by a machine they looked that good. You may find an automatic helmet useful as well if you don't already have one for such precision work.
Although I have also seen the same gas meltable fillers you mentioned. I've seen pictures of plugs done with these rods and they literally do blend in with the surface but I'm dubious as to how good they are if they're not sold along side TIG sets on any page I've found yet. There are special aluminium gas torches available for them but they're about £200-300 from what I've seen, and I've only ever seen one of them. If you have the money I would say you definitly should go for TIG. In the long run you'll most proberly thank yourself because you'll be able to weld literally anything you come across to anything else that will join to it. AC TIGs are quite expensive however and the smaller home shop ones, like the EconoTig, start at $1000 - 1200 with an entire kit, torch, clamp, reg, video, remote control. You're at an advantage if you get TIG also as you already know two handed welding. I've only just bought an oxy/fuel torch and it's tricky for me to say the very least. Check around first, especially on Ebay, for demonstration sets and such that are going much cheaper than the boxed version. Miller, Hobart, ESAB and Lincoln are the places to start for AC TIG sets that are genuine quality, ESAB in particular. Good luck with your bike intakes and let me know what you decide on because I'm quite interested in TIG as well.

Best wishes,
John
Please mail me with anything interesting you find on: info.host@btinernet.com

By hawgwild Date 02-11-2001 15:53

Thanks for the replies...I had a feeling that this was what I was going to hear but was hoping that some changes had come about in the 15 or so years since I welded for a living. As this is a low budget home project there's no way I can justify a $1000+ expenditure for a TIG welder unless I had a bunch of other projects lined up where I could recoup it's purchase cost, and I don't. I think instead what I'll do is make it out of mild steel...the flanges will be a pain to make out of steel, but I can do it. And I can use exhaust tubing for the runners, which is easy to work with and welds easily with my MIG welder. It's a shame, I really wanted it made out of aluminum, but I guess I have to admit that it's just not going to happen with my home equipment.

By RonG

Date 02-11-2001 16:29

Aluminum can be welded quite well useing Oxy - Acet torch.
Bear in mind aluminum is a "Heat Sink" and you must preheat then you must be able to put the heat in faster than it can disapate to maintain a puddle. It can work for Small light jobs.
Yes there is "stick electrode" and it works well in some applications, not sure about yours, Nor you machine.

I will repeat the part about "PreHeat" with out it you need one hell of heat in put.

By hawgwild Date 02-11-2001 18:20

Ron, thanks for the reply, could I ask you for a little more detail? Remember, while I spent several years as a welder, it's been years since I've been in the business and I have no contacts at all. Is there a rod number for the stick and gas welding methods I should be looking for? I'm more than willing to experiment to perfect the technique, but if I could short circuit it a bit by having the right rod, and some guidelines it would be great. Also, which do you recommend, oxy/acetylene or stick to do the job I described in my original post? Is a special torch required for the gas method? Do you know of a book, or a website that could provide me with some guidance? I looked at all the welding sites I could find last night, but came up empty. Thanks for any help.

Chuck

By John H. UK (*)

Date 02-11-2001 19:15

Hello again Chuck,
I find that's quite a common problem as well. Welding can be so diverse it can take literally days of looking to find one thing in particular. Not one to back down when faced by this I remembered seeing this page ages back and thinking 'I don't weld aluminium, and I don't need to.' so I deleted it from my favourites list. But to my amazment, ten seconds of searching and I've found it again. It used to be the curse of my welding searches because it would always come up but had nothing of interest on it for me. It's called TinMan and they supplier jewellers etc with micro torches. As well as... yes! aluminium brazing, soldering and welding rods.
http://www.tinmantech.com/html/welding_supplies.html
You don't need the torch I spoke about but I think it was designed to supply a very confined, TIG like, flame (Made by Primus and uses air/propane). Still though, I'm not sure if it's actually any use. I've seen pictures of these rods being used with just a plain oxy/acet welding tip and on this TinMan page they're welding a wing together with the preheat flame on a cutting torch. Perhaps you could order a couple of these and ask them how you set about using them. I think they have a book as well but I haven't looked for months.
Could you help me with something? When you oxy/acet weld do you make an oval pattern with your torch, 'milk churn' it, weave it or just move it linerly back and forth across the weld? I tried the ovals etc but my wrist aches so much after just a few seconds of holding the torch like that. I've resorted to crouching over the work, resting the torch base on my knee and just pivoting it from side to side as I move along. Do you think I'm holding it incorrectly because I really don't see how anyone could hold the torch in the fashions described. I need to know because the heat being, radiated I think, is burning the tip of my nose so I have to wear a baraclava now! I look just like I belong in the SWAT.
Good luck again,
John

By RonG

Date 02-12-2001 23:44

I have never used a flux coated aluminum filler for OAW, just plain old GTAW wire or as John say "TIG".

If you pre heat the pieces to be welded to 400 deg F you can run a very nice smooth puddle and it is clean providing you have clean material to start. An old timers trick is to adjust your tourch to a carburizeing flame allmost pure Acet. then blacken the material near the weld area then set a netural flame to preheat, when the black burns away it is ready to weld or you can just invest around $3 in a "Temp Stick"

As John said you need an AC machine to provide the cleaning but just as inportant is AC gives a hotter arc. There are gases that increase the weldability of aluminum like Helium because it can increase the heat of the plasma at the surface of the work.

For John.

SMAW is "STICK welding" TIG is really GTAW and MIG is GMAW

G for gas,T for Tungston, M for machine and AW for Arc Welding. Not that it matters but you asked. Also GTAW and TIG is sometimes known as "HeliArc" particularly concerning aluminum.

Hope I have been some help.

By 357max

Date 02-12-2001 15:05

The 110 volt input MIG welder may be used to weld the aluminum. Use the following helpful (hopefully) hints. Use 0.035" diameter 5356 electrode wire. Use 100% argon shielding gas. Once system is set up. Set spoolbrake tension to minimum, just enough pressure to keep the wire from free unspooling. Set drive roller tension to minimum (just enough to feed wire). Set gun cable and keep it as straight as possible (no kinks or coil). Use a brand new contact tube (tip). Cut the electrode wire at a sharp point angle (diagonal) before striking the arc each and every time. Never!! start arc with wire that has been arced. Use a push gun angle (point in the direction of welding). With 1/2 inch of wire sticking out past the contact tube, have the wire feed from gun to the work at a glancing angle. Never have the wire approach / hit the joint at a 90 degree. #1 set the wire feed speed to get the penetration, leave it alone! Adjust voltage to get the bead profile (flatness more voltage - more buildup less voltage).
Miller Electric makes a small Spoolgun to fit on a 110 volt primary input machine. It would take care of a lot of the potential wire feeding problems associated with the long MIG gun cable. Hope this gives you some ideas.

By hawgwild Date 02-12-2001 17:11

Wow, thanks for the detailed info 357Max, that really helps alot! Considering I now have 3 options, stick, gas and MIG, and each will cost me about the same to implement, I'll need to buy a used DC reverse machine for the stick rod (unless the amuminum rod will run on AC, it calls for DC reverse), an argon bottle and new liner and tips for the MIG welder or get a set of bottles for my torches, which method will work the best and be easiest to learn to get a sound weld from? I'm leaning toward the MIG, but I'd like to hear what you all think.

Chuck

By 357max

Date 02-12-2001 18:38

I would stay away from SMAW & OAW because of the flux. That stuff is very corrosive because of the salts. If water mixes with the flux/slag residue, that fluxing will continue to etch the aluminum until it is literally eaten away. To remove the flux completely requires lots of hot water and stainless steel brush scrubbing. If you can't get to the backside of the joint to clean it spells big trouble. Thats why the GTAW process was developed. It eliminates the need for flux.

By John H. UK (*)

Date 02-12-2001 19:24

Isn't SMAW Shielded Metal Arc Welding? MIG in plain talk? MMAW is stick, Manual Metal Arc Welding and that uses the flux covered rods. MIG uses exactly the same 'fluxing' / inert atmosphere techinque as TIG (GTAW, Gas Tungsten Arc Welding). I don't understand why we have these names, MIG / TIG / Stick are much more self explanatory. Chuck, all it means by reverse is the polarity of the electrodes is reverse, obviously. The wire from your MIG is then the positive and the work the negative. Lots of reverse polarity welding is done in DC. It makes the bead much smoother as it runs much hotter, current meets the higher resistance of the wire first I guess. For your aluminium this would be a concern like one of the posts says because you really do need to get it the weld hot. You find that if you buy a MIG set you will weld with one polarity using inert gas and another using the flux cored wires. I _think_ it's reverse in gas. Must have something to do with the temperature of the flux and getting the best vapourisation of it. All you do to reverse polarity is swap the connections over on your welder's front (Make sure it has some method of doing this). Some have switches but if you haven't paid for it you don't get it. It took me quite a while to learn to use MIG properly as I had no one to teach me (The breakers went every four seconds as well) and I really do heavily suggest you get someone to just look at the beads you run to say whats wrong. I gave my brother a hand reluctantly after him mocking me when I bought I MIG welder for christmas 2000, and he was able to run near smoothish looking beads in about a night after only a few goes. Not very strong welds at all but close to being alright. Everyone I've met always tries to run the thing along like they're on Aliens or something, like 10 meters a minute. I find it's best to think of it like soldering, you draw a bead on the wire and drop it onto the work then move it along, trying to maintain that blob as long as you can without breaking it. TIG is so good on aluminium because, of coarse, the heat involved forms your oxide real fast in open air, even in an 'inert' gas atmosphere. The funny thing is that the aluminium oxides are removed by switching the polarity of the arc. So you could strike an arc, stop, change polarity by hand, strike another and then it would clean away the oxide. That's humor for you. So aluminium is usually welded on AC which swaps the polarity many tens of times a second. One heats, the other cleans. I had a dream last night that after 2 months working every night at ASDA from 12pm to 7am I would be able to afford an AC Esab Handytig and auto-helmet. I couldn't sleep for hours, I think I might need counceling. I'm not sure if I'm right but I think it was MIG after TIG because MIG was used to fill the demand for really quick welding, TIG is far from quick. TIG AC runs a high frequency over the arc's current to keep it very stable. I've yet to look into pulsed modes on MIG.
The fluxes in OAW and MMAW are corrosive though and if you do choose these you might be better off looking for some seriously powerful solvent to clean them off, as well as an angle grinder wire brush attachment (Don't let it roast your work while you're polishing it). I believe the Tetrachloroethylene and Trichloroethylene solvents used in laundrettes are used for removing grease films on metla but I'm not as to how good they are on fluxes. A !VERY! serious note: BOTH these solvent decompose in arc radiation to !PHOSGENE!, you !MUST! take extreme care with any solvent near welding (Like wearing a full face respirator and doing outside with a fan on). If anything I've said confuses you, except my fantasies about Esab, let me know.

Take care,
John

By hawgwild Date 02-14-2001 01:56

I want to thank everyone for all the replies, I think I have enough info to make a decision now. As soon as I do I'll pick up the needed supplies and start practicing and I'll let you all know how it turns out.

Chuck

By dee

Date 02-24-2001 21:45

TALK TO FOLKS AT ALADDIN WELDING PRODUCTS 616 243 2531 THEY MAY HAVE A TRIAL KIT THAT AVOIDS ALL LISTED PROBLEMS AT A COST OF AROUND FIVE BUCKS (YES YOU READ IT RIGHT $5.00)
THEY SUPPLY MANY FILLERS, BRAZES, AND SOLDERS USED BY MILITARY

ESAB MAKES STICK ELECTRODES THAT WORK WELL WITH OXY ACETYL FLUX CLEANS QUITE EASILY IN WARM OR HOT WATER BUT I USE IT FOR HEAVY BUILD FOR BROKEN BOSSES ON CASTINGS
COLOR MATCH IS OUTSTANDING
IT WETS WELL BUT I AM NOT SURE HOW EASILY IT IS TO GET TO FLOW INTO CAPILLARIES AND WOULD BE CAUTIOUS
LIQUIDUS AT SOMETHING OVER 500 F ; USE CARBONIZING FLAME SOOT TO INDICATE TEMPERATURE- IT DISAPPEARS NEAR 500 OR SO SHORTLY BEFORE FILLER MELTS
COST IS ABOUT $20.00 AS I RECALL

By Darvin

Date 02-27-2001 18:23

You may want to consider structural grade epoxies. The type that need to be heat cured to that they will maintain shear strength when in a heated environment. 3M has some that require 350 F for 60 minutes to cure and have high tensile strength. I know guys use this stuff for V8 intake modifications. If your manifolds will fit in the oven (and you don't tell your wife), this may work.

By airweld (**)

Date 03-17-2001 17:35

Another reasonable option is to get everything fitted up and take it to a pro TIG weldor for final weld. Not as much fun as doing it yourself, but I think you would have the best result for the least expense. Good luck.