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smokin_dodge
04-21-2009, 05:59 AM
so ive been practicing my tig lately, and every now and then ill get some minor contamination, what looks like air contam., when welding aluminum. ive normally been running about 22-23CFM @ around 100-120 amps, depending on the piece of scrap. am i running enough gas?

19662
04-21-2009, 07:59 AM
I would have to say your pressure is fine. I dont run that much unless there is a breeze in the shop. The contamination may be coming from your filler or inside the cup. Just my two cents though !

Supe
04-21-2009, 08:56 AM
That's on the high side for your CFM, you're wasting gas at that point. Back it down some. Check your hoses for leaks, but watch your angle, too. Too high CFM and the right angle will create somewhat of a venturi effect and draw air into the gas column.

pulser
04-21-2009, 01:16 PM
Just a minor point about shield gas pressure and flow rate. The relevant factor to shield gas in welding is flow rate, generally measured in cubic feet per hour (CFH).

A flow meter controls the flow rate at any given pressure. The floating ball type flow meters for shield gas are designed to function accurately at one given pressure, generally 30 psig. The orifice type flow meters function as you increase or decrease the pressure and thereby increase or decrease the flow rate through a fixed diameter orifice.

Craig in Denver
04-21-2009, 11:43 PM
At those amps, paying for my own argon, I run 12-15 CFH.

I recently found that alum won't put up with the same stickout as mild steel, for me. I use a #7 cup, 3/16" max stickout. Indoors. And now, a gas lens. Outside corner joints give me more shielding trouble than others. Pepper in my beads, filler turning to ash instead of a chrome ball and almost no oxide cleaning zone is my clue. Sync 250, x-former, balance 3.

Being in class long enough to identify my problems; keeping the torch angle as steep as possible is most difficult. TIG also likes a very short arc length, try for less than 1/8".