Please help me understand freq./balance

[Robbbby]

I have some flat aluminum sheet that I have been toying with, in hopes of being able to understand different settings so that when the time comes I can choose the proper frequency/balance to do a job. Unfortunately Going back and forth with different settings I am not seeing any relation how they work or do anything differently.

Machine I am using is a TA185 with a 3/32 thoriated tungsten, no pulse, machine set to 140A max.

I first set the machine to 70hz, 20% balance
- I was able to lay a decent looking bead that flowed nicely, seemed to require lots of heat to get started.

Second setting, 70hz, 65%
- Could not even make a puddle, my tungsten balled up until it was inside the cup, this happened pretty quickly.

Third setting, 130hz, 65%
- Same thing, could not create a puddle no matter how much heat I put into the piece, tungsten just balled up into the cup fairly fast

Fourth setting, 130hz, 35%
- Was able to lay a decent bead, could not really tell any different between this and the first setting besides the higher frequency noise the machine makes.

Am I doing something wrong, that the tungsten melts at 65% balance no matter the frequency?

What effect does frequency have on the weld I keep bouncing around with different settings but can't understand the relation. I find can do fairly nice welds with the balance anywhere below 50%, anything above that and magic doesn't happen.

[hankj]

The balance sets the % of the cycle that will be negative. At 20% EN, you have the cleaning action of the positive polarity for 80% of the cycle. When you start getting into high percentages of EN, heat becomes a problem. As you found out, the tungsten melts!

As for frequency, I have mine set at 130 Hz. for aluminum because I was taught to set it there! A wonderful fellow by the name of George Bright, who recently passed away and who I met on this forum (Sundown) was my mentor and over-the-phone instructor.

I'm a long way from a good TIG weldor, and I don't see much difference in frequencies, but some of the really good hands will help you out, I'm sure.

Hank

[SundownIII]

Robbbby,

I can't speak directly to the settings for the TA 185 since I don't own one, nor have I used one. The closest I come is having used the Dynasty 200 DX.

The balance setting determines the percentage of time (per cycle) that the machine spends in electrode negative (penetration--heating the plate) and electrode positive (cleaning--removing oxides). The higher the percentage of time you spend in electrode positive, the more cleaning you achieve but also the more heat you induce in the tungsten rather than the work. Generally a setting of about 35% electrode positive will provide sufficient cleaning. As you reduce the amount of electrode positive the cleaned area adjacent to the weld bead will get smaller (layman's terms).

The frequency(cycles) determines the number of times, per second, that the arc alternates (switches) from positive to negative. On a transformer based machine (Syncrowave series for instance) the frequency is set (for the US) at 60 cycles per second (as provided by the power company). On inverter based machines, such as your TA 185 you can adjust the frequency. The higher the frequency, the tighter the arc and deeper the penetration. The lower the frequency, the broader the arc and lesser penetration (broader bead).

Real basic but hope it helps. For a more detailed description, you can download Miller's Handbook for GMAW (Gas Metal Arc Welding) from their main page or order a hardcopy. Great basic guide to Tig welding.

[river-rat]

Higher frequencies will narrow the arc cone and produce a more DC-like arc. Check out the 200Hz video from htp (way at the bottom of the page) http://www.htpweld.com/products/tig_welders/tig201.html

[Robbbby]

When would you use a high balance percentage?

[Mr Meck]

I would use a higher balance on the cleaning side for a cast AL oil pan that held oil since 1972. Being cast, it has casting impurities, being soaked in oil it has hydrcarbons in the holes you cannot see, till they explode from the tig heat.

[Rocky D]

Something about aluminum, lost of folks don't know...it retains moisture, like it is porous...before starting to weld preheat using O/A...flash it with acetylene, turn it black, then heat it up till the black disappears , and you'll be at welding temperature.

[hankj]

...preheat using O/A...flash it with acetylene, turn it black, then heat it up till the black disappears , and you'll be at welding temperature.

Best tip I've seen yet!

Hank

[jerryo]

Don't know how the controls of your TA185 are set up. but my Dynasty 200dx welds clean 1/8" aluminum nicely with about 65-70% balance and 120hz at ~ 115-120 amps.

[MXtras]

When in doubt, run it balanced and go from there.

When welding cast, I have found it helpful to cook it at at least 200F for a while to burn out the moisture and then use as little heat input and duration as possible. Get in, weld and get out. Dwelling during the weld can pull crap (silicone) out of the adjacent material and really bugger up your weld. I weld a lot of old and new engine/transmission cases on ATVs and MX bikes and this method serves me well.

Scott

[newbie]

On the T/A the balance is backwards from some machines. So you'll want 20% for 80% welding. Don't worry about the balled up tungsten. Once it *****(*****?) up it will last longer and not drop tungsten into the weld. You should be close around 20% and 130. Keep the gas 15-30. Start with higher heat then reduce it after your first welds or it will move too fast.

[Robbbby]

On the T/A the balance is backwards from some machines. So you'll want 20% for 80% welding. Don't worry about the balled up tungsten. Once it *****(*****?) up it will last longer and not drop tungsten into the weld. You should be close around 20% and 130. Keep the gas 15-30. Start with higher heat then reduce it after your first welds or it will move too fast.

Ahhh so the balance is backwards compared to the miller machines? No wonder I keep reading about people saying they weld easy with 70% balance with the miller units, that would be 30% on my machine which works wonderfully. Now some of the replies in this thread make sense, thanks guys.

[Brianstick]

I'm surprised your balance knob doesn't say "max cleaning" on one side and "max penetrating" on the other, so you'd know.