Tig welding aluminum radiator help

SchmidtFabrication · Sat Jul 18, 2015 2:42 pm

Hello guys and girls I'm new to this forum and I'm having some trouble with a radiator today. It's a brand new core that I am building custom ends tanks to. I have wire brushed and sanded the aluminum on the radiator and when I goto weld the end tanks on it's almost as if I'm trying to weld raw aluminum to anodiozed aluminum. I'm getting a lot of trash floating around in the weld puddle.
I'm using a miller Aerowave with a 1/8" 2% thoriated tungsten small gas lense with a #6 cup #20 profax torch

http://s1206.photobucket.com/user/weaks ... %5B/URL%5D

Braehill · Sat Jul 18, 2015 4:57 pm

Welcome to the forum, feel free to use our introduction page and tell us a little bit about yourself, first name , welding background things like that.

Just to establish a baseline to work from I'm going to ask a few basic questions about your set up. Have you welded with this exact set up in the past without problems? By that I mean same cylinder of Argon, same torch, cup ,back cap, the whole nine yards. Why I ask is it looks like you have contamination in the gas. That means there's any number of areas that it can be coming from, including bad gas.

Check your system for leaks, especially in the low pressure side from the machine to the torch. It can be as simple as a broken o-ring in the back cap drawing in atmosphere or a leak in the torch hose doing the same. An easy test to rule out gas problems is to light up on a piece of steel (shiny clean) until it puddles and let off the pedal and hold the torch there for about 10 seconds or so until the puddle cools, if it and the tungsten both stay shiny then it's most likely not the gas.

Once we rule the gas out we can go from there.

Len

Oscar · Sat Jul 18, 2015 5:47 pm

Along the same lines, you can weld up two small pieces of aluminum scrap using the same cleaning routine to see if it behaves the same way. Usually aluminum is less forgiving to gas contamination from what I've seen.

SchmidtFabrication · Sat Jul 18, 2015 7:32 pm

It's not a gas issue cause I was welding on other pieces of aluminum with the same settings and the same gas had no problems welding with it. I have never welded up end tanks on a custom radiator before. Not sure if I need a different kind of filler rod. I tried both 4043 and 5356. Same results.

Sat Jul 18, 2015 7:45 pm

That core has extruded parts that likely have a film of oil on them. Aluminum oxide (you can't avoid it) is porous and absorbs a bit. The only solution I see is to hot-tank the core in a degreasing solution, and you'll likely still get a li'l pepper in your welds. The cosmetic solution is to weld it, prove it tight, wire-wheel the hell out of it, and then wash over the welds to dress them up. The realist solution is to weld it, prove it tight, and send it on it's way. It does not have to look perfect to do it's job.

Steve S

big gear head · Sat Jul 18, 2015 9:18 pm

I'm pretty sure that the tubes in the core are furnace brazed in place. The braze material may have spread over the surface and may be causing problems. Just a wild guess.

I've welded on several of these radiators with no problems, but not close to the tubes.

Rick_H · Sat Jul 18, 2015 10:20 pm

I fab intercooler and radiators also usually no issues.

Who's core is it? Did u use a brand new sanding disc? Dedicated or new brush?