pulsed tig

[wendell]

The big Blue Lump is running great. One more question...

I seem to pulse just about every thing I weld (aluminium and steel). I get better penitration w/ a smaller HAZ and it's a lot easier to attain the "stack of dimes" everybody is looking for. For steel I usually set to about a pulse /0.5sec, 50% on time w/ a 25-50% difference in amps. My question is, what are the drawbacks? Are there times when I shouldn't pulse? Is pulse a crutch to make up for poor skills w/ the torch?(It sort of seems that way)

I moved this out of my other post on a differnent topic. Any oppinions/ advise would be great. Thanks for your time.

[Mike W]

Which big Blue lump do you have? I have a Syncrowave 250 at work and recently got the optional controls installed. I have played around with the pulse settings, still experimenting.

[Blown S-10]

i have yet to use pulse, though i have tried it just to "see" the pulsing.
i don't have a good understanding of it. if it is there to reduce heat, why not just turn the amps down . i can do dimes on aluminum easy. steel, no real dime effect.

[HAWK]

wendell,

Pulse is a great training aid. At a low frequency of .8-1.5 pulses per second you can really concentrate on adding filler and getting the stacked dimes effect. It serves many other uses also. Many people associate pulsing with less heat input and greater arc stability. It is a great tool for welding material
less than .065". At some point the peak amperage will become too low to use pulse effectively. For example at 10 amps peak and 5 amps background pulsing is probably not very useful.

Pulsed GTAW can also be used at a high frequency of 300-500 PPS to agitate the weld puddle. This is very useful when welding cast aluminum and anodized aluminum. With cast materials the high pulse rate helps float impurities to the surface creating a cleaner and stronger weld. The high frequency pulse rate actually helps penetrate the anodized coating on some aluminum products and makes them considerably easier to weld. Pulsing can also be used to tailor the welding arc for spedific joint types that can present difficult in welding. For example a fusion welded corner joint at 250HZ is more likely welded with a mid range pulse rate than without pulse.

Is pulse a crutch? Yes and no. You should be familiar with pulsed and non pulsed GTAW techniques. This will broaden you welding experience and make you a better welder.

Blown S-10,

I hope this helps explain pulsing a little bit. It is a lengthy subject and had myriad uses depending on the machine, weldment, and operator. Have fun with your Dynasty D200DX!

[wendell]

Thanks a lot Hawk,
Thats about the line of thought I was on. I have found it very helpfull to weld thin stuff. I haven't seen the pool aggitation effect yet but will try increasing the frequencey next time I'm welding cast Al. Can I set the PPS high enough on a syncrowave to achive this effect?

Mike W,
I've got an old syncrowave 300 that has all the options availible in 1979. Got the power source and a big Bernard chiller in separate auctions at Ebay. Had a buddy w/ an extra foot controler and regulator. Broke down and bought a new torch. Put the whole thing together for less than $1000.

[72boss]

Wendell

Pulsing is an excellent additive to any machine. It is definately not a crutch. You can make superior welds on certain materials with the use of pulsing. Pulsing is very effective on auto sheet metal, where different thicknesses of metal are commonly joined. As to your question on skills, It takes skill to use the pulsing technique correctly, possibly more skill than without pulsing. Pulsing will definately allow better control of heat and you seem to be utilizing this ability.

[eric75]

How does pulsing effect welding in AC? Are there two different superimposed wave forms? Like a high frequency switching form DCEN to DCEP and on top of that a lower frequency change in amplitude?
I myself have never used any pulsing feature, but I have had to be pretty active with the pedal when practicing on .030 Aluminum. Almost bouncing the pedal in coordination with the fill rod. Is that anything similar?

Correct me if I'm wrong, we use low frequency pulsing to help with adding filler and high frequency pulsing (in addition to AC) for busting up impurities? What about the mid range between 3 pps and 300 pps, does anyone ever use that?

So far I haven't needed any sort of pulsing to get the much coveted "stack." That just came from burning up lots of filler on scrap.