It's been a while since I've posted here, but I have a few questions. I realize gas welding (I say gas, because I'm not limiting to oxy-acetylene, I'll get into that in a minute) is not very popular nowadays. It would be far more efficient to use a tig welder for anything you would use the tanks for, and sometimes even a mig is a better choice. But for not having access to a 220 where you're working, or not having a couple thousand to shell out for a TIG, I think a gas setup can be pretty efficient.
I used gas quite a bit in vocational school. I even considered gaining a certification, but my teacher was adamant that I would be wasting my money, that there was no call for it nowadays, so I instead spent my time on MIG and TIG certifications.
My biggest question regarding an oxy-acetylene setup is do you guys generally use a flux, and if so what kind when welding mild steel. Stainless steel? I remember at the JVS, we used flux coated rods, or TIG rods. I can remember however that when just using the TIG rods, the puddle fought me, and while porosity didn't appear to be an issue, I did have to work harder to get a nice bead.
My second question is regarding welding aluminum. I opened a thread on this a few years back when I was still in JVS because my instructors just plain didn't think it was possible to weld aluminum with oxy-acetylene. I knew this wasn't true, however I still didn't find a whole lot of information on doing it.
Since the time I made that original thread, I've read two books with updated information that suggests that a few advancements have been made in gas welding aluminum, including number one being the addition of aluminum brazing rods that seem to work very well, according to the authors.
I also read, that a oxy-hydrogen setup, with blue welding goggles is a more efficient setup when welding aluminum and I was wondering if anyone has any experience with this. The text I read seemed to indicate that flux was very important when welding aluminum (and stainless for that matter, especially in lue of pipe welding, coating the inside in lue of running argon through the pipe you're welding)
I was wondering if anyone could answer the few questions I've presented, and possibly add anything to the topic of gas welding aluminum.
Mathius
Hello Mathius;
I started out welding with Oxy-Acetylene.I really like the process and still use it on aircraft framework.However,it is slow and expensive since the price of all gasses has skyrocketed recently.Over time,the price you pay for the gas will be higher than your investment in a tig.The Miller dynasty series of tig welders can operate on 110 volts all the way up to 460 volts 3-phase without changing any links.The only change is to connect the red lead to the 3d leg.Simple.Lincoln also makes inverter tigs that are equal to the Millers.If you are not planning to weld very thin metal,a Miller Econotig might be a good choice for you.A complete unit can be purchased new from Indiana Oxygen Co. for about $1300.These guys are a real pleasure to deal with and have an online store on E-Bay.I have also seen used Econotigs up for bid on E-Bay,for much less.
If you want to weld stainless or aluminum,I would strongly advise using a tig.It is possible to weld aluminum with Oxy-Aceteylene but,tig is much easier and will do a much better job.
Flux is not used on mild steel.
Mathius,
welding aluminum with oxyacetylene isn't impossible but it's for sure very difficult. Much better is to use TIG.
You've got to wear blue goggles when using an oxyacetylene torch. The black mask worn for arc welding is too dark.
For welding iron with oxyacetylene you don't need to use a flux, but you need to use a desoxidant (derusting) paste. No rust or oxide can be present in the metal.
Giovanni S. Crisi
Sao Paulo - Brazil
A very easy way to weld aluminum with OAW is to use a SMA Aluminum electrode - use it a lot like a brazing rod, keeping close control on base temp 'til you just get the filler to flow. A slighty carburizing flame helps to reduce oxides. Scratch the filler as you add it to help break oxides away.
On a good day I used to demonstrate welding the bottoms of 2 aluminum pop cans together. (use a glancing flame just above and on the joint)
I meant blue goggles, vs. the green.
Yes, green of course. I said black because it looks as if it was black when you're not wearing it.
Giovanni
Goto http://www.tinmantech.com/
While a decided commercial bias, is quite informative on alumlnum and seems to be quite accurate
Mathius,
Aluminum can be welded with the oxyfuel process, however it should only be used for noncritical applications or repair when situable inert gas hielded arc welding equipment is not available. The advantage of the process is the simplicity, portability, and the low cost of the equipment. The disadvantages when compared to arc welding are numerous. Here's a few: An active welding flux is required to clean and protect the aluminum from oxidation, welding speeds are slower, heat affected zones are wider, weld metal solidification rates are slower, which increase the possibility of hot cracking, the gas flame offers no surface cleaning action, welds are likely to contain large numbers of discontinuities, and distortion is greater. Standard oxyfuel gas welding torches are suitable for welding aluminum sections about 0.03 to 1" in thickness. Thicker sections are seldom welded because the limited heat available from the flame makes good fusion difficult.
Acetylene is the best fuel for oxyfuel gas welding of aluminum because of its high combustion intensity and flame temperature. A neutral flame is best, but a slightly reducing flame (excess fuel gas) reduces the possibility of forming unwanted aluminum oxides. Hydrogen may be an adequate fuel for welding thin sheet sections.
Aluminum welding flux is designed to remove the aluminum oxide surface film and exclude oxygen from the molten weld pool.
During welding, the flame is initially moved in a circular motion to preheat both edges of the joint uniformly. The flame is then held where the weld is to begin until a small molten pool forms. The end of the filler rod is fed into the molten pool to deposit a drop of metal and then withdrawn. This is repeated as welding progresses using the forehand technique. The flame should be oscillated to melt both joint faces simultaneously. The inner flame cone should not touch the molten weld pool, but be kept from 0.062 to 0.25 inches away. The crater should be filled before removing the flame.
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