Mig Voltage Levels

[clint738]

This might help
The wire feed speed is in direct relation to the amperage at a given wire stickout (length of wire from the contact tip to the arc). The voltage is in the case of a CV (wire welder) the constant and is the length of the arc from the end of the wire to the weld pool, as you change the wire stick out the amperage changes to maintain the weld voltage. A normal wire stick out for short circuit mig welding is 1/4".

The following example may help you understand this with .035 ER70S-6 wire and C25 shield gas set at 20 SCFH flow.
1/4" wire stickout, volts 17 and wire feed speed 150 IPM = 100 amps
3/8" wire stickout, volts 17 and wire feed speed 150 IPM = 50-60 amps due to the resistive heating of the wire between the tip and the arc the weld current drops to the level required to maintain the set voltage.
If you were to reduce the stickout to 1/8" the weld current would increase to approximatly 150 amps to maintain the set voltage.

Typical min and max ranges of each wire diameter for ER70S-6

.024 minimum 30A 15V 105 IPM WFS, maximum 150A 21V 710 IPM WFS
optimum vert. setting 80A 18V 310 IPM WFS
optimum horiz. setting 110A 21V 465 IPM WFS

.030 minimum 50A 17V 95 IPM WFS, maximum 200A 23V 600 IPM WFS
optimum vert. setting 100A 18V 235 IPM WFS
optimum horiz. setting 150A 20V 385 IPM WFS

.035 minimum 50A 18V 75 IPM WFS, maximum 225A 25V 500 IPM WFS
optimum vert. setting 150A 18V 185 IPM WFS
optimum horiz. setting 215A 22V 415 IPM WFS

I hope this helps more than confuses you.

http://www.hobartwelders.com/weldtal...ire-Feed-Speed

I see you have both the millermatic 211 and the 252. If you were to try to weld 1/4" steel with both welders, would there be much difference in the arc of the two welders?

Both using .035 wire with C25 shielding gas, flat, vertical, and overhead welding.

I'm starting to wonder if I should consider the 212 or the 252 since this will be a structural project with up to 1/4" plate and beams, or can the 211 handle even load bearing projects without beveling these joints.

There will only be T-joints and Lap joints and I have never heard of beveling either of those so need the welder to single pass the joints.

[Broccoli1]

I didn't like the MM211, really just a personal thing I guess with the Arc characteristics- I really like the Passport Plus that I have but it is an Inverter based machine.

I never really ran the MM211 on anything thicker than 1/8"

The MM252 is sweet but again we really don't run that thing hard either-

Over bought on that purchase but we needed to spend money before the end of the year that year so we went ahead with the MM252.

The 15' Gun actually makes a difference for me on the machines. I know you can roll the smaller machines around but even on my small 3x6 table the extra 5' just makes it a little easier.

Miller doesn't recommend a 15' gun on the MM211 or Passport but I know one member that put a 15' Bernard gun on his passport w/o problems ( drive roll system supposedly doesn't have the power to push the wire through the longer guns so life of the motor could be cut short)


I would look at the Hobart IM230

http://store.cyberweld.com/hoir230migwe.html

Really good price and you get a lot of power so you won't be wishing for more and Hobart's customer service is on par with Miller.

You can check out reviews here

http://www.hobartwelders.com/weldtalk/forum.php

[Cgotto6]

Like I already said, anything from the 180 up will easily handle quarter inch. There will be no difference in weld quality if the same operator used any of these machines. Proper joint prep is mandatory for any machine.

Based on what you have said I would hire a professional welder to do this structural project. Not a good idea to teach yourself how to weld on a structure that could kill someone if it fails.

[clint738]

Like I already said, anything from the 180 up will easily handle quarter inch. There will be no difference in weld quality if the same operator used any of these machines. Proper joint prep is mandatory for any machine.


Based on what you have said I would hire a professional welder to do this structural project. Not a good idea to teach yourself how to weld on a structure that could kill someone if it fails.

Well I wouldn't say I'm completely new to welding. I grew up around welding since my parents owned a oil field welding business for almost 30 years. I grew up stick welding and spent every summer stick welding for my parents company, was a shop welder, welded sometimes at oil rigs, welded some at the potash mines and on one bank construction job as an iron worker.


I just haven't had much experience with mig except my MM140. So I'm essentially trying to get more info on the mig process from those more experienced for thick material Mig applications.


i fully intent to destructive test my welds to verify the welder settings and different methods for each Mig position to be welded with the same material thickness used. Hopefully through testing I can refine things but want to get as much info as I can so I can minimize the amount of material used for testing. Steel plate isn't cheap these days.


I took off work today and went to the Airgas +45 miles away since the local Airgas doesn't even have Miller mig welders on display to look at, they just have Lincoln Migs. Looked at the Miller weld samples for the 211, 212, and drooled over the samples from the 252.


i was impressed in how the mig gun on the 212 and 252 looked compared to the mig gun on the 211 which has the same gun as the 140 I had sold.


I was also really impressed with the drive roll setup on the 212 and 252 compared to the 211. So after comparing the prices and what I will be welding in the future, I went ahead and bought the 252.


While the 252 requires a more expensive spool gun, I won't be doing aluminum any time real soon, so I will save some and buy the spool gun when I have a project for it. This should be a mig I can't out grow.


Now I just have to wait for my account to be setup at Airgas so I can rent a C25 mix bottle and start welding. They said it takes 24hrs at least, so now I have to wait till at least Monday before I can get a bottle of gas to test the welder.


Can't wait to test the new 252!


Thank you all for your help and recommendations.

[5440]

As an EE I think the higher voltage machine is due to higher voltage drop that occurs with the higher currents explained by Ohm's Law: V=I X Z. Pump more current (I) through an impedance (Z), you get a voltage drop..here that would be at the electrode. This explains why you can't measure the voltage of a dead car battery unloaded. No load means no current flow through the high internal resistance (because it's chemically dead) and a false normal voltage reading only to find the battery has a large internal voltage drop (large current thru the higher than normal internal resistance)=low battery terminal voltage when the engine is cranked. For the larger MIG's they probably design the higher open circuit voltage based on full load current to give the required terminal (electrode) voltage.