Just for clarification, you're referring too welding at same current/voltage levels only changing the input power?

 

Yes, on the Miller machine the company actually said you would notice a difference.

JanErik

 

Hey Jan,
I'm sure you will get varying opinions as to what brand vs another brand delivers a "gentle" or "harsh" arc. Many say Miller is a "gentle" arc & the Lincoln has a "harsh" arc. I've never noticed any meaningful difference as I used a Lincoln 255 at work & I have Millers in my shop. With both units, an exact input voltage, I cannot "see/feel" a difference. I would agree that a voltage disparity from 208v to 230v will be indicative with the arc.....remember, with unchanged unit settings, the lower input voltage will have a lower output. For the average user, I don't think anyone would find a difference that would be noticable or be detrimental. As far as your perspective with a "penetrating arc" or a "shallow arc", with all heat/wf parameters the same, the position of the gun will determine the depth or shallowness of the weld. A 90* position will have the deepest penetration & as angle is reduced <90*, the penetration is reduced, although does give a flatter profile. The thicknesses of material & joint configuration will be the major factor as to what position will give desired results. Also, another consideration is whether you prefer to "push" or "pull" as we each prefer our own like/dislike. All factors the same, "pull" will give a deeper penetration & many who do a lot of flux-core which is "pull", will do the same with gas. I'm one who "pulls" for f-c & "push" for gas. I simply use the angle parameter to adjust the bead I want. It's really all up to you as far as what you like, have success with, & obtain the desired results you expect.

Denny

 

Thanks Denny..yea all those factors you mentioned due make a difference, but I was trying to drill down to what "IS" a harsh or gentle (or whatever term is being used) difference?

I know from experience the ESAB 250 MigMaster has a good arc that "seems" different from the others...but trying to define what that is - I don't know. I'm sure it has something to do with the waveform that advanced process are utilizing now.


JanErik

 

I've noticed that changing wire speeds slightly can make the arc behave in a harsh/rough way or can make it feel soft and almost buttery, Spatter also seems to increase and decrease with the arc. I think it really has a lot more to do with the settings and the shielding gas/wire than the actual machine. Aside from the settings about all there could be is how the current is rectified and filtered between the transformer and the weld.

 

Hello JanErik, I believe what may influence items such as "gentle"/"harsh" arc could be the result of the slope curve that has been engineered into a particular brand or model of CV power source. Some machines are non-adjustable in this regard and have a flat slope, others are set to a steeper slope, this variance can cause the type of conditions that you mentioned in your post. Still other machines have the ability to change the internal or external connection of the taps attached to the windings of the machine to vary the slope characteristic. Finally, there are machines that use potentiometers to vary this relationship and are widely adjustable from the face of the power source and require no dissassembly of the power source. Below is a link to a page from ESAB giving a bit of a description of how this works. Hope you can get something useful from it. Best regards, Allan

http://www.esabna.com/EUWeb/AWTC/Lesson2_22.htm

 

Miller would have you believe that inductance would be more important. High inductance machines react slower to varying current demands (more voltage fluctuation). Low inductance machines react more quickly or more violently even.

The Millermatic 350P has an adjustment for this, but I can honestly say operator technique is much much more important. Its a fine tune feature.

Older machines might have had a big crank on them that actually lowered more metal into the core windings of the transformers.

More reactive gases, like CO2, make for harsher arc as well. Try MIG welding with C10 for a change...

 

There are or may be several factors that affect the operation of the machine and have an effect on the behavior of the arc.

Regarding input voltage, different machines may behave differently if the input voltage varies from 'nominal'. The machine's circuitry may or may not give a differing output (voltage and amperage for the arc) if the input voltage (from the wall outlet/plug) changes or varies. The 'lower' end machines would probably be more likely to behave like this, as the circuitry is more of an 'open-loop' type. Higher-end machines may or may not behave like this.

quick example: Machine is set up and running with 240V input from the wall, and the operator adjusts the machine's voltage and WFS parameters to give a certain/desired arc. Then the machine is plugged into a different outlet where the actual voltage is only 208V (could happen in a business/industrial setting where the single-phase wall outlet circuit is fed from a leg off of the incoming 3-phase supply and thus the actual voltage at the oulet is 208V and not 240V, or there is a lowered voltage because of electrical loads either in the building/plant or at the power-company side of things). Same settings on the machine and now the arc is different because the incoming voltage from the wall outlet is lower than it was before.

Why is the machine behaving differently now? Because the incoming AC voltage is run through various circuits in the welder, the first usually being some sort of transformer that changes the incoming AC voltage from the 200+ V AC (or whatever the incoming AC voltage is) down to a more arc-welding applicable voltage of maybe 15-30V. Still AC voltage though. After going through the transformer, then the voltage is run through the rectifier (diodes) and changed to DC voltage. Then further circuitry may shape and 'adjust' the voltage in different ways as well (capacitors to 'smooth' the AC ripple a bit and inductors/'chokes' to change/adjust how the output DC voltage behaves during actual welding). Some machines may have adjustments for the output inductance ('harsh/crisp' versus 'soft' ) that let the operator adjust (or mess up ) the arc behaviour further.

Some machines have various incoming voltage taps or adjustments that change where/how the voltage is run through that transformer in order to ginve the 'desired' lower AC voltage. If the incoming voltage does not match up with the machine's settings and circuitry, the output results are not what is expected or desired (usually). Chnage the incoming voltage tap or adjustment to match what is coming from the wall (208V versus 230/240V), and the machine and output settings match back up with the original circuitry design better.

As to how different machines have 'differing' arcs, sure. Goes back to the transformers and the diodes/rectifiers and the capacitors and the chokes/inductors inside the machine all affecting how the arc behaves during actual welding (which is typically NOT just a steady-state DC output voltage, especially for short-circuit transfer-mode wire welding).

Changing the weld parameters (voltage versus amperage/WFS, the actual shielding gas being used if any, the wire parameters/chemistry, etc, etc) all have an effect on how the arc is behaving during welding.

There, clear as mud now? :dizzy:

 

Moonrise is the first one to use the terms Crisp and smooth. Some welders can be adjusted some can not. Some call it puddle control and some call it pinch. This is what you could be noticing on your machine.

What this adjustment is for crisp or smooth or harsh is the energy used to clear the short when welding.
Each z of the Buzzzz while you are welding is a short of the wire to the work then it blows off and starts over again.

My best example is my Miller passport which was designed to run short circuit mig with Co2 gas. It has a paint ball gun Co2 tank inside the welder. The inductance is set for Co2 best smoothest weld.

My SP100 is designed for C/25 gas and welds best with it.

Both machines will weld with both gasses. A decent operator will get the welder set so there is minimal difference.

Smooth = Flatter bead, less penetrating
Crisp = quicker cooling bead easier to weld out of position. More spatter.

It depends on what you are doing, type of gas, joint design, position, job, gun angle, ........

David

 

Jan

If you want a detailed explanation, I'd recommend you go to Millerwelds.com and click on the Resources Tab. They have, available for download or purchase, an excellent GMAW handbook that goes into detail on your question.

Too much involved to type it out here.

 

Dan, who is member, is a great resource on describing the difference and what causes the difference. there is some good threads on this subject over on Hobart's forum.

 

Scott,

The point is, this is not a deep dark secret.

The information is out there in as much detail as one wishes to pursue.

Personally, I prefer to do the homework and read information from "established sources" rather than listening to the "opinions" of others who may not know anymore about the subject than I do.

Guess I haven't adapted to the "Spoon Fed" generation.

 

I understand and agree. My wife wonders what would happen if I went blind and couldn't read. When we go to a mall she parks me at the bookstore.

 

I have 92/8 for pulsed spray. Mig welding with it is too soft of an arc and it does not get a lot of penetration. (more like straight argon). Turn the "arc control" towards "crisp" Or lower numbers and the arc is more aggressive. Only to a point.

Its different enough that I keep C/25 on another mig welder.


My pass port has "Soft" for stailess. It seemed to work the one time I used it on stainless with trimix.

Arc control, inductance, pinch puddle cotrol.......


David

 

I'd like someone to explain to me better what's going on during the weld.

I CAN tell the difference when mig welding between two different brand machines on C25 mild steel when the short circuit arc is "Harsh" vs. "Gentle".JanErik

Could be a lot of things there, I've never seen a "Harsh vs. Gentle" control. On the two knobs usually provided, were they the same?

I saw a video from Miller where the Miller spokesman explained you might notice the difference with different voltage inputs INTO the machine (208V vs. 230V, etc..) and how it changes the feel of the arc.

So what's exactly happening with the arc on this difference?JanErik

You're trying to get the same work done using near 5% less or 5% more fuel, that puts the machine design curve in a different place. If you leave the dials on the machine alone and just change the input voltage you'll see a difference.

I'm guessing it's also explained as a penetrating arc vs. shallow arc?

JanErik

Prolly not, if it's open arc, short circuit MIG you're asking about... Or are you wondering about the whole inductance/reactance thing? Then, as above, the terms are more usually "Stiff vs. Soft" and "Crisp vs Buttery". The terms have context and also meaning in relation to building power supplies...

Matt

 

Thanks for all the replies...and I do appreciate all the "opinions"...

Yes - I can read up the facts on a engineering site, but the forum is more fun.

and yes,, I will be checking the the AWS sites too to understand this better.

cheers...



JanErik