test welds on aluminum pipe

[fishmaster]

Hello,
I am trying to weld some samples on Aluminum Anodized pipe and I can't seem to get the "Dimes" effect that everyone is looking for. I am using a Syn. 250, 50 series, sched. 40 aluminum anodized pipe, 5356 1/8 rod, 3/32 pure tungsten, pure argon shielding gas.
I can get the effect on a flat surface or "brushed" aluminum but not the anodized. What am I doing wrong?
1. How tight a fit is required on the coped joints?
2. What amp settings are best?
3. Do I need to grind the anodized coating off?
4. What technique is best to achieve the "dime " effect?

Any suggestions will be most helpful!
Thanks
Mike

[HAWK]

Mike,

The first thing is to deal with the anodized coating. If it is not critical to the finished product, then clean it off. An angle grinder with Scotch Brite pads does the trick as will a stainless steel wire knot rope brush on an electric angle grinder. A light hand with a good grinder will also work.

You will have a hard time welding through the anodized coating unless you are running an inverter arc with a high pulse rate creating tremendous puddle agitation or running 100% helium shield with your Syncro-250 without pulsing.
The helium creates a much hotter arc that helps to weld through the anodizing. However, you will still have to grind a small amount of anodized coating to initiate the arc and get it stablized before welding through the anodized coating.

[bail76]

The only other thing I would add is for your type power source is to switch from the pure tungsten to zirconium (brown band). The zirc. has a higher current carrying capacity and will not break down as easily as the pure. Good luck.

[HAWK]

Good Point!!!

bail76,

Good Point!!!

Zirtung is the best thing I have ever found for the Syncrowave series.