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some beginner questions (duty cycle & arc force)

G'day,

2 questions I have. The machine is an Esab AristoTIG DTD 250 AC/DC.

1) duty cycle on my machine. In the manual, it states '100% 200A' for TIG, but only '60% 200A' for SMAW. I thought this very strange

Also, as the manual states, when the machine is switched to SMAW mode (instead of TIG), the fan comes on continuously, also when not welding. In TIG mode, it turns only on when actual welding is being done. So, the question is, what's so special about SMAW, does it put more of a burden on the machine than TIG?

2). arc force. Quote from manual:

'Arc-force monitors the metal transfer and produces a short current elevation when a short cicuit between electrode and weld pool is detected. This current surge destroys the short circuit bridge. An optimized setting of arc-force leads to perfect welding processes even with difficult kinds of stick electrodes'.

Since I want to make perfect welds (hey, the machine says it will do that for me!), how do you determine 'optimum' ? If it's too low, I guess the short won't be blown away, but if it's too high? I don't see a problem there, which probably means I'm missing something. For the moment, the arc-force (aka 'DIG'?) is simply turned up to maximum. Maximum=optimum? Then why the knob in the first place...

Peter, The Netherlands.

Reply to
peter_dingemans
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Doesn't make sense to me but maybe someone has a explanation.

This I can help with. With arc force turned high enough it can be possible to push the electrode completely through the work. In other words if arc force is turned to high then the arc will likely end up to hot for the work and cause undercut and other problems. This varies with machine, operator, electrode, work size, and what phase the moon is in so there's no cut and dried setting that is right. You just have to try it and see what works for you.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

Power = volts x amps = Watts

The voltage for SMAW is higher than for TIG; hence, the power output for SMAW is higher; therefore, the machine works harder and must be given time to "cool off" when doing SMAW.

This sounds like some sort of "anti-stick" mechanism to help you start the arc when doing SMAW. Having it set low is most likely the way a regular stick welder would behave. Turning it up should make the electrode "stick" less when starting the SMAW arc.

Reply to
Speechless

The relation betwen the volt and the current is: for TIG V=

10+(0,04*value of current) and for SMAW is V=20+(0,04*value of current) this mean that at the same level of current the power in SMAW is more higher; the maximum power that can dissipates the machine (power circuits) is constant so the duty cycle must be reduced in SMAW.

The optimum arc force is that give you the maximum speed in welding without spatters outside the welding bead, normaly for basic electrode is 30%. For rutile electrod is not important because the transfer of the electrode is not for short circuit (like basic one) but with little drop like a spry.

Reply to
angelo

Thanks Angelo and others,

This makes sense. Also explains why I didn't notice any difference in the setting, I've so far only used rutile electrodes...

Speechless, it's not a hotstart function; there's a hotstart on the machine too, but it's different from the 'arc force'.

Funny thing: my father gets more beautifull welds (beads) with hotstart and arc force turned fully down... The only machine he ever used in his whole life is an old beaten up transformer welder. He does appreciate the ESAB though, esp. with stainless steel electrodes (he always welded them AC, and with OCV of about 40V whereas 70-80 is stated as the minimum requirement).

At his age, he most appreciates the fact that he doesn't have to bend down to adjust the coil like in his old transformer welder. A potmeter at 1m above the floor is so much easier... (yeah, I know, it doesn't justify the purchase of such a machine, but it's surely nice).

Peter, The Netherlands.

Reply to
peter_dingemans

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