hotponyshoes
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Yes. Works very well on stainless providing you can keep it in perment contact.Just a noob question. Will a fully backed heat sink allowed full penetration? He mentioned 2,5mm. It will draw a lot of energy out of fusion zone.
never did a job like that. Just curious.
A bit of copper and the perfect settings on the welder and you can get a weld that needs very little, if any, cleanup on either side.
It's a bit more of a mission trying to do it on this length of run though.
For a start, the price of a bit of copper big enough to do it is probably going to cost more than just buying the right size sheet special order in the first place.
Obviously it won't work with any sort of metal backing that can fuse with the weld as they will just stick together.
If I had to do something this size unless the budget allowed me to buy a nice length of 50mm2 copper bar I would be thinking something along the lines of:
Tig, clean up a bit of heafty angle/flat/whatever I had. Clamp both sheets togeather along the length with no gap. 2 clamps each end. Load of tacks 50mm or so apart, no filler, start in the middle, do 10 or so then check the sheet was not rising up. If it was remove 2 clamps at one end, beat it down with a hammer and reclamp. Once the whole thing was tacked cover that side with aluminium tape, flip it over and run the other side from the center to the outside as fast as I could, again, no filler. Either rig something up to bolw air over the weld attached to the torch or better yet get somebody else to help.
Flip back over to the front side, burnish off the alloy tape and use a spool of mig wire for filler and just run along as fast as I could. Again, cooling will help with the distortion but you will still need some hammer work to finish up although that's not much of a problem on sheet that thickness.
For mig, just get some of this
Weld Backing Tape
Argweld® Weld Backing Tape™ allows faster welding speeds and greater production rates. Argweld® Weld Backing Tape™ welds joints from one side only, eliminating the need for double sided welding.
www.huntingdonfusion.com
You can then clamp down to any old dirty bit of backing or even just put it on a flat surface with some weights on top to keep it down.
That tape also works fine with normal mig/tig but then the clamping/cooling is still just as important. Just by using pulse you will save a load of distortion. If you can get access to a double pulse machine it will be even easier as you get the benefits of pulse but with more time for the heatsoak to do the work. Although you also need a big enough heat soak as eventually it will become saturated and if its too small a faster run in pulse might be better then get the workpiece off quick (or cool the whole lot) as soon as its done.
Another option would be to try something like a length of copper pipe and run water through it although you will need a couple of vee blocks (or something equivalent homemade) to clamp it up any sense.
Or get a length of 3mm+ alloy box section and use a wood router to cut a groove along it and push some argon through that to back purge which will get a clean weld although it will still be a bugger to clamp up and you will still need a bit of post cleanup on the backside.