Aluminum radiators

By firewelder Date 10-19-2002 00:32

Looking for advise and tips. I weld performance radiators/intercoolers at a local shop. The cores are premade and I fab/weld the tanks(.060-.125). The cores are nitrogen brazed(?) called nocolok(spelling?). Does anyone have any tips on prepping the cores. I use a SS wheel/brush to clean the scale followed by alcohol supplied by the shop. I am using 4043 and sometimes 5356 wire(tig). I am using a Miller 250 Syncrowave set on AC, high frequency @50%, and pure tungsten(balled). Sometimes the weld is real nice and sometimes no matter how much you clean the core it welds as if contaminated. I have worked with welders(co-workers) who use 2% tungsten with no tip prep at all. I have tried that but like the pure better. Any advise and tips on prepping,welding, weld set-up would be appreciated.

By awill4wd (**)

Date 10-19-2002 07:10

Firewelder, by coincidence as a part time interest of mine, I also weld alloy performance radiators and intercoolers here in Australia.
If your cores are anything like the ones I weld here, they are actually furnace hydrogen brazed.
I use 2mm sheet for radiator core end tanks and 3mm sheet for intercooler core endtanks. The material I use is grade 5052.
I prefer ceriated electrodes ground to a point. My next preference would be Zirconiated and an Argon flow of 7-10 litres/minute at the torch ceramic gas lens.
Like you, I also use either 4043 or 5356 welding wire. I would set your AC balance to around 3 or 4 on the dial. (more cleaning)
I think you'll find your main problem is getting rid of the furnace braze process which covers the entire core header plate assembly. I had exactly the same problem, and I tried using stainless wire brushes like you but it's too deeply ingrained to remove.
Solution, easy. Before welding, I file back the header plate where I am welding to base aluminium material. It's easy to see as it's shiney underneath the grey furnace braze.
I think if you file before welding you'll have no problems.
Please let us know here how you get on.
Regards Andrew.

By awill4wd (**)

Date 10-19-2002 07:29

Firewelder, I forgot to say in my previous post that filing the area to be welded works on both tube & fin and bar & plate intercooler cores.
On the bar & plate cores I file about 4-5mm down the core face, this is going to be covered by weld metal anyway so doesn'st show up. Just be very careful when filing, you don't damage the fins.
Also, only use the file for the intercooler/radiator cores, do not use on anything else, to prevent contamination.
By the way. What brand of cores do you use?
Regards Andrew.

By firewelder Date 10-23-2002 01:24

Awill4wd, welding aluminum radiators etc. is also my part time job. I believe you are correct with the cores being furnace hydrogen brazed.I also use 5052 sheet.I have never heard of or used ceriated electrodes. Another welder I know uses 2% thoriated . I have tried that but if the balance is set at 3-4 the electrode really gets contaminated. Does the point stay or does it ball up like pure? How often do you have to regrind the point due to contamination? I use a screen lense and ceramic cup with the argon flow at 15-20 lpm. If I set the balance at 3-4 it seems to contaminate the electrode to much. I usually set the balance at 5-6. Will ceriated correct this problem? Sometimes I use a grinding disc on the outside of the header followed by stainless wheel to remove the grit. I will try to use a file and see the difference. With your technique do you have any problems with the scale?
Some brands of cores we use are "Heatex", "Thermasys",and "Active Radiater."
Thanks for your help.

By Kix474

Date 11-02-2002 04:58

I also prefer 2%ceriated or orange tungsten. It is way harder then pure and thoriated tungstens and holds a poit at higher amperages. Also does not contaminate very easy,u can dunk it or hit it accidently and it won't leave your big black mess like the other tungstens. Don't get me wrong u can't bang it to bad, but slight hits or bangs won't leave your mess. Pure tunsten just sucks because the ball on the end liquifies real easy and you don't get a real precision ark and it contaminates real easy. thoriated holds up pretty good on your real thin sheet,but starts spiking as u get thicker like your .122 up to .125 wich is around how thick the side of my intercooler are. Some 3/32 ceriated tungsten would work real good for what u are doing u ought to try it. Ray C.