Theres been some referances to fusion welding lately as a method of minimizing distortion while welding sheet metal. I had to make a battery box and made pics to illustrate this technique. In brief, fusion welding is done with higher than normal heat for a very brief period, i do it with TIG but experts can use a torch. The first set of pics illustrate the tack weld. To tack the panels the panels must fit very tight. The currant is set quite high, normally that amout of currant would just blow-thru the sheet metal but you are very brief with the pedal. You have to take the weld on faith. What i do is get the lens close to the metal, hammer the pedal and roll the tig across the seal (top to bottom) and off the pedal; move ahead and repeat. It happens so quick you won't see it weld. Hit the pedal, get off and move. On the long side of the box it took less than a minute. The first pics shows the start of tackwelds. The 2nd pic the box ius tackwelded. The 3rd and 4th pic shows the tackwelds with a dime for contrast. the 5th pic i lightly clamped a piece of wood as a gage for distortion.
The welding is the same 'take it on faith' technique as the tackwelding. The heat is high and once you strike the arc you don't quit moving your hand until you reach the other end. It is done all in one motion. You don't stop for anything. If you see the puddle form you are too slow! What i see is the seam getting bright and shinney. Your have to support your hand and be careful supporting the hose, once you hit the pedal you can't let the hose deflect your hand on the way across the seam. The 6th pic is the box fully welded, the 7th is a closeup of the weld and you can see it is done in one motion. The 8th and pic pic has the same piece of wood laying on the seam and you can see a slight crown that may well be from the bending in the brake. It isn't the normal distortion associated with welding because it is going in only one direction. In any event it can be removed easily. Notice too, there was no filler rod used. None. Thats why it is called fusion welding, you fuse the two panels together. I hope you find this useful, oj
Not to be picky, but all welding is fusion welding, ie: the fusing or joining of two metals together What you have described is called an autogenous weld, or a weld made without the use of filler rod. I remember something from welding school.... that and keep your head out of the smoke
i made the battery box in my `28 tudor out of stainless , used basically the same technique....no filler rod , just tig'd it up. it's been fine for 15 years
My hands used to be that steady....50 years ago. After discovering sex and alcohol it all went downhill.
Y'all can correct me if I'm wrong, but I fuse a lot of Stainless and it works fine (under little to no stress). However, if it's Mild Steel and takes anykind of stress, no filler rod makes it somewhat fragile and more likely to crack and failure.
This does hold some truth, however if one was to pull enough of the matireal into the pool/puddle of the metal being fused togather there will be no problems. Now I wouldn't recomend this for any type of structual project, but hey a battery box I don't see a problem at all.
I was thinking about that after I wrote it. I agree. For a battery box it would be fine, but like you said anything structual... Not so much. Thanks
If the gap is as tight as a gnats ass, then no filler rod is needed. The puddle will fuse the metal just fine, and it will be strong too. If you are trying to bridge the Grand Canyon with your weld, then bulk extra filler metal is definitely necessary. As with many things, welding prep begins with having clean bright parts that actually fit together.
If there is any other type of welding besides fusion welding, I would be very interested to hear of something completely new.
Terminology is not different, fusion welding is just that, welding with many different processes causing the metal to fuse together. Making a weld without filler metal is called an Autogenous weld. Look it up in the AWS process handbook, under GTAW. Funny how things get twisted around sometimes. http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding http://www.mwsco.com/kb/articles/19990330e.htm
When I weld sheet metal I just tack weld then stitch weld the rest moving from one side to the other to keep the heat down . I have seen that welding done on you-tube before but I really don't trust it for doing patch panels and places like that . I just want to make sure I have no problems so I guess I will keep doing it the way I have been . It looks good but I surely wouldn't want the battery box to give way and have a battery getting loose in an engine bay ! So isn't is safer just to weld it together ? Just my opinion ! Retro Jim
Done properly an autogenous weld is as good or better than any other weld. 100% fusion and a good weld, just don't try to grind it, which won't be needed anyway. It's welded have no doubt about that.
By the way, using the foot pedal on the TIG you can do an autogenous weld as usual with the metal fitted and tacked tightly. Using the foot pedal to control amerage you can indeed see the weld puddle and you can proceed at a speed that will allow you to watch and join the metal properly. No need to hurry or rush or run blind. Just take your time and feather the pedal to get the weld current you see you need. Much better than a "take it on faith approach". When I weld I like to be in control, that's why I like my Diversion 165 with the foot pedal and high frequency start so much.
Yup, Spot welds, friction welds, laser welds, and electron beam welds are state of the art (if done properly)..... no filler rod required.
Naw, it's just us here below the Mason/Dixon line in the US what ain't got a bunch of edumacation and been work'n in the construction feild and sweat shops that call it this mostly.
I think all you guys have missed the point. If that steel were .125 thick or the piece were being welded to the chassis then i can do whatever i want and play with the pedal and filler rod to control heat because it won't matter, i am simply welding a chunck of steel to another chunk and that is that. But what i am demonstrating is a technique to weld 18 or 20ga steel together with minimal distortion. There isn't any hammer and dolly work required! I didn't stretch the metal after tacking, i just welded it up! If that were a top beinmg chopped instead of a battery box i'd be fussing over a skim coat right now while other methods would have two people wailing away with hammer and dolly trying to beat the hell out of that metal to stretch it back into shape. Believe me, when i say you don't have time to see the puddle form, i mean it. This technique is that fast. If you are playing with the pedal and watch the puddle then you'll have to develop some very good metal shaping skills because there'll be a ton of distortion in the finished product. Again, i am working with sheet metal and trying to make distortion free welds. Look at the HAZ (narrow and continuous), it shows it all. A normal TIG weld will show the HAZ looking like a bunch of catapellars walking in line. Between each 'catapellar' will be a 'low' spot where the metal has shrunken even greater than the middle of the 'catapellar'. And each of these low spots will take a lot of hammer and dolley work, then you'll have to hammer and dolley the whole row to stretch the metal back into shape - ask anybody that has chopped a top and made a cut across the roof to make it longer. This is a fwiw tech piece, if you can get something out of it fine. If you are welding heavier gage of metal then you don't need to try this way. If you are doing structural then i'd be sure of a good fillet with plenty of rod. Not sure where the term came from, heard it called that from a fellow in england while gas welding a 5' seam on an aluminum fender/running board with minimal distortion. He said that he just fused it together.
Huh, I guess I have been Autogenous welding without realizing it. Doing exhaust tubing with the oxy-acetylene, I get a good fitup, and apply some pressure to push the pieces together. Apply heat and just as the puddle forms the seam just closes up. You can see the butting faces sort of wick together just as they reach melting temp. Keep moving the heat with just a tiny puddle, just watch the seam as it closes together and stay ahead of it. Makes for a very clean looking seam. The line is still visible but no bead. I beat on some practice pieces with a hammer and it held together quite well. I don't think I'd do it on a structural part, but for exhaust it works good.
I didn't miss the point, I do that kind of welding all the time. And it absolutely doesn't need to be done fast at higher amperage. I can weld two pieces together as you explained and take my time watching the tiny little puddle while running just enough amperage to make the weld. Lower amperage = the same results. Small autogenous weld with very small heat affected zone and no distortion. I just don't have to hurry. My welding credentials in case anyone is curious: 56 yrs old, started welding when 18 1st class Journeyman-Pressure-TIG welder on piping -pressure vessels. Presently teaching welding in Canada's largest trade college (last 13 years)
Didn't mean to insult you, i don't doubt your credentials and i've been welding a while myself. This is all about sharing info and you have specialized knowledge, add to this thread. This is important stuff, welding sheetmetal is an art form. Put together a tech piece and (hopefully) you can explain it better than i did. oj
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