manual GMAW with 3 settings (volts WFS and amps)

Date 11-09-2007 15:15

Hello Clif, it is likely that "third" dial or control that you've seen is the inductance control, or in some cases referred to as pinch effect, or any number of other names. Depending on the manufacturer and the time period that the machine was produced in, this control could serve a number of different purposes, but essentially it does allow for some additional adjustment of the arc characteristics of the machine. Not all machines have these controls as you readily pointed out. Best regards, aevald

By d-on Date 11-09-2007 20:42

Typical GMAW operation is such that the wire feed speed controls the amperage. The amperage control is reflective of the amount of resistance in the circuit, and since the variability in the circuit for resistance is the amount of wire crossing a given point during a given amount of time the amperage is variable. This is why you probably won't find such a machine as you are describing. I do agree that the Inductance control will make big differences to your arc when you are welding. If you are welding ferrous metals then your setting would be to the lower end. If you are welding stainless steel then it would be to the upper end. When welding flux cored wires you would typically be in the middle range. I think a significant step forward is a "new" machine Miller has introduced. It is a step up from the XMT, it is an XMT 350 MPa. The step up here is that you can now set your average voltage while you are setting up your pulsing parameters instead of only being able to set the arc length or trim. You still can but this new change makes pulse welding with the old AWS D1.1 PQR format easier to work with. I just reviewed the machine and I recommend taking a look at it. It also has a companion GMAW only machine.

By Plasma-Brain (**)

Date 11-09-2007 21:57

Thank you both for your input,
I have run machines with inductance settings before and it does make a world of diffrence. I wish that I had the picture or knew where to find it again because I dont think it was an inductance adjustment,
but I have no way of proving it.
So unless anyone knows where I can find a bunch of old lincon catalogs... I think im stuck. :(

However, d-on got me thinking a little...
Please correct me if im wrong, but a constant current machine has a series circut for the arc and a constant voltage has a parellel circut?
Is thats why the wire feed speed determens the amperage?

If this is the case, if you were to make a CC GMAW machine, would you be able to set the amperage and wire feed speed seprately??

thanks again,
Clif

By aevald

Date 11-09-2007 23:07

Hello again Clif, in the case of using a constant current power source for operating a wire-feed system, the feeder has the ability to sense voltage changes related to arc length and either speeds up or slows down the wire advance to maintain a consistent arc length. When the arc length is lengthened the voltage goes up and the feeder increases the speed to compensate and maintain the arc length, when the arc length decreases the voltage goes down and the feeder decreases the wirespeed to keep the arc length constant. That is a simplified description but basically covers what is happening. Thus in this case the amperage remains relatively constant and the voltage is the varying factor. In CV mode the opposite is basically occuring, the voltage is remaining constant and the amperage is varying depending on the amount of wire that is being fed into the weld pool. Here again a simplified definition but basically describing what is occuring. Best regards, aevald

By DaveBoyer (*****)

Date 11-10-2007 06:21

What does the Power MIG look like if it has the spot timer option? Could that be what You saw in the picture?

By Plasma-Brain (**)

Date 11-10-2007 18:17

http://content.lincolnelectric.com/pdfs/products/literature/e757.pdf - this ones a powermig 350Mp, page 5 has the front panel
http://www.completeweldingonline.com/Qstore/Apdf/PowerMig_255.pdf - this is a 255 with the spot timer on page 4

The machine im thinking of looked alot like the 350 MP, the olny diffrence is that there was another big black dial on it right below the other 2.
Given that, and knowing that designs change alot before they are released, mabey the 350 was the machine I saw.
I saw the picture around 2001 and im not sure when the 350 came out, but mabey Lincolns marketing department jumped the gun a little?
the PDF for the 350 is dated 9/07, but I dont know if thats when the PDF came out or the machine its self...

aevald, thank you for the clarification,
Simplified or not it helped me figure out that what im looking for either doesnt exist yet or is way more complicated than I was hoping for...
still, ive figured out what I needed to know and given that, Im off to go acquire a little buzz box wire spitter.
It might be cheating, but im going to use it with my TIG so that I dont have to worry about feeding wire by hand... ;)
Ill let everyone know how it turns out.

thanks again for the info everyone,
Clif