Tig welding stainless sink bowls

admin

Hi guys. I recently started a job doing commercial stainless work.Im having issues welding a sink bowl onto a bench. The problem im having is ripples on the bench top along the weld join. Although this is acceptable at this workplace and the other welders benches come out the same I dont like it.Im hoping someone with this kind of light gauge stainless experience can give some advice.I will go through the procedure I use.Firstly both bench and bowl are 304 and its 1.5mm thick.I start by tacking the bowl into the bench with tacks at 25-30mm apart. I position the join corner to corner. I can see that these tacks are actually the cause of these ripples as they slighty distort the metal so I try using low amps, 35 amps,  and no filler wire as that seems to make it worse. After its tacked up I can already see the ripples in the top.Before welding I get some aluminim flat bar, 100x10mm. I sandwich the bench top between 2 ally bars. One on the bottom right in the corner and on on top about 5-10mm from the seam. This is to prevent the whole bench buckling.When welding I turn it up to 45-50 amps. I dont use filler wire. Instead I fuse it at a fairly high travel speed.To finish I use a 5" grinder to clean the weld and buff it with a grey mop or black wheel on a barrel grinder.I haven't had any fail but I don't like the ripple finish. I'll take some pics at work tomorrow and post them.Some advice from someone who has done plenty of this work would be very much appreciated
Reply:Hammer and dolly. It's shrinking, stretch it back out. SMOOTH hard hammer face.
Reply:Also, weld opposite side of tacks if possible  ( tack back weld front ) and hammer as you go. I would set the amps at 60ish and quick on off tacks, tight fit, no filler and weld It out at about the 40 - 45ish like your were.
Reply:less heat more tacks. Mostly less heat. If you got a pulser try that. Or fuse it. i sometimes find stainless sinks on side of road in trash. We use them to make fuel tanks for our racer cars. They are cheap and work lol
Reply:Yes the tacks are definately shrinking it. It sounds like your talking about a flat butt join farm dog. But im refering to an outside corner weld.These pics show the bowl tacked into the bench. I couldn't get a good angle under the lights for the distortion to show up well. Though it was minimal on this one and hard to see with the burn marks still there.I am actually fusing it already, no filler.The machine has no pulse function.Considering the tacks are the cause of distortion, adding more tacks is bad because you get more distortion.I have been trying less heat on my tacks but I find interesting what farmdog suggested, hotter tacks. With less heat you need to apply the arc for a longer period. for it to reach its melting point.  Maybe a quick, hot, micro flash would be better. I will try it.Check out this function on the Kemppi machines called microtack. This would be ideal. Attached ImagesLast edited by porkncheese; 09-17-2015 at 05:44 AM.
Reply:Just curious what would happen if you used filler wire, possibly MIG wire for filler? I'm thinking the filler wire would add a little more strength so it wouldn't warp or shrink as much. Might allow for faster welding speed as well. You have to establish a puddle anyway.
Reply:Adding filler does give a weld more strength. In this case though extra strength is not required. Adding filler means I have to travel slower which could lead to further distortion. Adding filler also gives you more work when it comes to grinding it. Besides the issue stems from the tacks.I tried the suggestion from farmdog, turned it up to 60ish and flash it for a split second to tack it. I gotta say it works well. It leavesu with a little tack with minimal distortion.Another method iv been using is to melt the bowl edge first at 40-45amps and just flicking the puddle to the bench top side so that it gets minimal heat applied
Reply:not necessarily, filler wire on something that thin might not be needed at all. You just need a seriously tight arc gap, which can only be achieved with practice. There are techniques without pulse. Just use very low amperage(enough to melt the two) and then use a woodpecker motion to fuse it. I would not use filler, it will require even more skill/practice to achieve without warping and like I said a stupid tight arc gap. And you should tack it even more. and if its that big of a  problem just stick a heat sink on the back. Or weld a few inches and let it cool completly
Reply:You need to use filler if the results show a low weld. If the weld is not low, you don't want to use filler. That's all there is to it. Period.Welding/Fab Pics: www.UtahWeld.com