Hi All
Is it better when MIG welding to have the voltage setting higher than the current setting or is it better to have the current setting higher than the voltage setting?
Best regards James
MIG welding requires constant voltage-type power supplies.
This is in contrast to TIG, and "stick welding" a.k.a. SMAW which both use power supplies of the "constant current" type.
CV is crucial to MIG welding, it ensures a stable arc gap size, resulting in stable arc operation and smooth metal transfer from the wire tip.
The main difference between the two types is how they respond to varying electrical resistance in the arc. Keep in mind that the longer the arc is, generally the greater the resistance it has. In constant voltage(CV), increasing the arc gap size causes a drop in current, Therefore, according to "Joule's Law"
Power = voltage x current
this causes a decrease in the power and heat input of the arc.
In constant current machines, increasing the the arc gap *increases* the voltage, which causes the heat input to increase. So in summary, in a CV machine a longer arc gap is colder. In CC machines a longer arc gap is hotter, though the heat is a lot less focused since a bigger arc has greater surface area to give off it's heat.
So, why is CV important to MIG, then? If the arc gets too long the power drops, the wire tip stops melting. Then, the end of the wire advances closer into the weld, the power increases and the wire starts to melt more quickly again. This "feedback cycle" between the melting-off rate and heat input quickly results in balance between the arc length and the melting-off rate.
In MIG welding, it's helpful to understand the general rule-changing the wire feed speed influences the amount of current and heat input, whereas changing the voltage generally changes the arc gap size and the arc stability.
This is in contrast to TIG, and "stick welding" a.k.a. SMAW which both use power supplies of the "constant current" type.
CV is crucial to MIG welding, it ensures a stable arc gap size, resulting in stable arc operation and smooth metal transfer from the wire tip.
The main difference between the two types is how they respond to varying electrical resistance in the arc. Keep in mind that the longer the arc is, generally the greater the resistance it has. In constant voltage(CV), increasing the arc gap size causes a drop in current, Therefore, according to "Joule's Law"
Power = voltage x current
this causes a decrease in the power and heat input of the arc.
In constant current machines, increasing the the arc gap *increases* the voltage, which causes the heat input to increase. So in summary, in a CV machine a longer arc gap is colder. In CC machines a longer arc gap is hotter, though the heat is a lot less focused since a bigger arc has greater surface area to give off it's heat.
So, why is CV important to MIG, then? If the arc gets too long the power drops, the wire tip stops melting. Then, the end of the wire advances closer into the weld, the power increases and the wire starts to melt more quickly again. This "feedback cycle" between the melting-off rate and heat input quickly results in balance between the arc length and the melting-off rate.
In MIG welding, it's helpful to understand the general rule-changing the wire feed speed influences the amount of current and heat input, whereas changing the voltage generally changes the arc gap size and the arc stability.
James1000 wrote:Hi All Is it better when MIG welding to have the voltage setting higher than the current setting or is it better to have the current setting higher than the voltage setting? Best regards James
WerkSpace gives us a good answer (he always does, and thanks for that), but I choose to chat on about this question.
I suspect that several other questions lie behind this voltage / current question.
Several people whom I have helped in the past have asked something similar, when it was just one of a bunch of questions they wanted to ask. I had to prise out the other questions. And so I will presume that is the case now.
I haven't seen a huge range of welders (machines), but the kind often found in workshops, I'm prepared to guess, are equipped with a) voltage rocker switches -- 2, 4, or 8 on a dial (e.g. Hobart), and a continuous amperage dial; or, b) continuous dial for both amperage and voltage (e.g. Lincoln 180C); or, c) meters on both amperage and voltage, as well as continuous dials.
The difference between my b) and c) matters to people who have "numbers" they want to dial up and therefore proceed to "weld properly". Of course, after a year or so, welders "just know" how to set up and adjust, and use all sorts of information to help them put their experience into the work at hand.
Lots of things follow from this pretended knowledge about how welding machines are presented to us.
The first is, people starting to weld are told to listen for the bacon sizzle, or even, the hiss of compressed air. If your settings and technique are not close to the mark, this is not necessarily helpful. At the end of the day, it makes perfect sense, but starters want more advice on how to fix whatever it is wrong with their attempts.
The second is, (this ain't original, I know), there are many things that have an impact on how your weld turns out (length of stick out, angle of gun to work in two planes, travel speed, etc, etc, as well as voltage and amperage settings), assuming your metal is clean, earth is good, etc.
So, I have two suggestions, if I may, James1000: 1) try to better describe your issues, and put them up as questions; and 2) as a community, we need to find a good set of steps to help beginners set up and weld using the type 1 welder machines, with fixed but unknown voltage settings, and a continuous amperage adjustment. At least half of the rocker switch voltage machines do not publish the voltages (of whatever type, wherever read) that their machines provide at each setting, in my experience.
As a starting point, I suggest, especially with machines that set voltage with rocker switches, the set-up process begins with getting the amperage "into the ball park", based on the thickness of the steel; then setting the voltage that gives out the sizzle. Keep the stickup constant at about 12 mm (0.5").
If your machine does not have a meter for amps, then you have some homework to do: draw up a chart that relates burn-off rate for your chosen wire with the speed of the wire feeder in your machine.
Of course, if this process works, it works for all mig machines, not just machines with rockers.
I think it works. What do others think?
I suspect that several other questions lie behind this voltage / current question.
Several people whom I have helped in the past have asked something similar, when it was just one of a bunch of questions they wanted to ask. I had to prise out the other questions. And so I will presume that is the case now.
I haven't seen a huge range of welders (machines), but the kind often found in workshops, I'm prepared to guess, are equipped with a) voltage rocker switches -- 2, 4, or 8 on a dial (e.g. Hobart), and a continuous amperage dial; or, b) continuous dial for both amperage and voltage (e.g. Lincoln 180C); or, c) meters on both amperage and voltage, as well as continuous dials.
The difference between my b) and c) matters to people who have "numbers" they want to dial up and therefore proceed to "weld properly". Of course, after a year or so, welders "just know" how to set up and adjust, and use all sorts of information to help them put their experience into the work at hand.
Lots of things follow from this pretended knowledge about how welding machines are presented to us.
The first is, people starting to weld are told to listen for the bacon sizzle, or even, the hiss of compressed air. If your settings and technique are not close to the mark, this is not necessarily helpful. At the end of the day, it makes perfect sense, but starters want more advice on how to fix whatever it is wrong with their attempts.
The second is, (this ain't original, I know), there are many things that have an impact on how your weld turns out (length of stick out, angle of gun to work in two planes, travel speed, etc, etc, as well as voltage and amperage settings), assuming your metal is clean, earth is good, etc.
So, I have two suggestions, if I may, James1000: 1) try to better describe your issues, and put them up as questions; and 2) as a community, we need to find a good set of steps to help beginners set up and weld using the type 1 welder machines, with fixed but unknown voltage settings, and a continuous amperage adjustment. At least half of the rocker switch voltage machines do not publish the voltages (of whatever type, wherever read) that their machines provide at each setting, in my experience.
As a starting point, I suggest, especially with machines that set voltage with rocker switches, the set-up process begins with getting the amperage "into the ball park", based on the thickness of the steel; then setting the voltage that gives out the sizzle. Keep the stickup constant at about 12 mm (0.5").
If your machine does not have a meter for amps, then you have some homework to do: draw up a chart that relates burn-off rate for your chosen wire with the speed of the wire feeder in your machine.
Of course, if this process works, it works for all mig machines, not just machines with rockers.
I think it works. What do others think?
Thanks for the Information Guys!
I well using a CEA Maxi 401 Mig welding machine
When I am mig welding 4.5mm thick tube I have the voltage setting on the machine on setting 4 and the current setting on the machine on 3. When I am welding 10mm plate, I have the voltage setting on the machine on 4 and the current setting on the machine on 5 . In the first instance the voltage setting is higher than the current setting and in the second setting the current is higher than the voltage. Which makes the better weld, when current is higher than voltage or when voltage is higher than current?
I well using a CEA Maxi 401 Mig welding machine
When I am mig welding 4.5mm thick tube I have the voltage setting on the machine on setting 4 and the current setting on the machine on 3. When I am welding 10mm plate, I have the voltage setting on the machine on 4 and the current setting on the machine on 5 . In the first instance the voltage setting is higher than the current setting and in the second setting the current is higher than the voltage. Which makes the better weld, when current is higher than voltage or when voltage is higher than current?
- MinnesotaDave
-
Weldmonger
-
Posts:
-
Joined:Sun Oct 27, 2013 10:57 pm
-
Location:Big Lake/Monticello MN, U.S.A.
You have a lack of general knowledge with mig.James1000 wrote:Thanks for the Information Guys!
I well using a CEA Maxi 401 Mig welding machine
When I am mig welding 4.5mm thick tube I have the voltage setting on the machine on setting 4 and the current setting on the machine on 3. When I am welding 10mm plate, I have the voltage setting on the machine on 4 and the current setting on the machine on 5 . In the first instance the voltage setting is higher than the current setting and in the second setting the current is higher than the voltage. Which makes the better weld, when current is higher than voltage or when voltage is higher than current?
Your voltage is at no time higher than your current (amps).
Check the included pic (left column) and you will see for 4.5mm thickness your voltage should run about 18-19 volts.
Your wire feed speed about 320-340 inches per minute with .035" wire.
That wire feed speed equals roughly 160-170 amps.
Go to the Miller online calculator link and familiarize yourself with some settings. http://www.millerwelds.com/resources/ca ... ulator.php
Good luck and ask more questions if you have them
- Attachments
-
- mig settings.GIF (68.41 KiB) Viewed 4858 times
Dave J.
Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~
Syncro 350
Invertec v250-s
Thermal Arc 161 and 300
MM210
Dialarc
Tried being normal once, didn't take....I think it was a Tuesday.
Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~
Syncro 350
Invertec v250-s
Thermal Arc 161 and 300
MM210
Dialarc
Tried being normal once, didn't take....I think it was a Tuesday.
- Otto Nobedder
-
Weldmonger
-
Posts:
-
Joined:Thu Jan 06, 2011 11:40 pm
-
Location:Near New Orleans
For reference, the numbers on your "current" dial versus the numbers on your "voltage dial" have no realistic comparison to one another.
A MIG machine is a constant-voltage source, meaning when you set a voltage on that dial, that's the open-circuit voltage the machine is "fixed" at.
The wire speed is apparently marked as "current", and this is roughly true, but a "4" on voltage and "3" on current does not mean you actually have more voltage than current. These are relative settings, and the numbers may as well be apples and oranges.
You need not actually know the theory to weld well, but the short form is, the higher the set voltage, the more current you can carry in the weld (You can have higher wire speeds with higher set voltage).
Thinner metals call for lower voltage, thicker metals, higher, and the "current" (wire speed) is adjusted to match, to achieve the best power transfer, which is usually the smoothest arc.
Steve S
A MIG machine is a constant-voltage source, meaning when you set a voltage on that dial, that's the open-circuit voltage the machine is "fixed" at.
The wire speed is apparently marked as "current", and this is roughly true, but a "4" on voltage and "3" on current does not mean you actually have more voltage than current. These are relative settings, and the numbers may as well be apples and oranges.
You need not actually know the theory to weld well, but the short form is, the higher the set voltage, the more current you can carry in the weld (You can have higher wire speeds with higher set voltage).
Thinner metals call for lower voltage, thicker metals, higher, and the "current" (wire speed) is adjusted to match, to achieve the best power transfer, which is usually the smoothest arc.
Steve S
Steve, thanks for your help. I am sure this voltage / amperage question is as old as the hills. But can we do a little more with this?
Does the old "rule", one amp for every 1 thou of an inch of steel have any validity? I assume that if the rule has validity, then it is valid for all welding processes, not just stick welding (where I first heard about it).
My observation is that if the voltage setting is too high, you get burn through. If the amperage (wire speed) is too high, you just get bad welding.
The capacity of welding machines is determined by how many amps they can deliver.
So, a set of procedures for start-up welders would be (a suggestion for discussion, not a view set in concrete) 1) determine the thickness of the steel; 2) set the required wire speed to deliver the amps you need for your diameter wire; 3) set the voltage as high as you can to get the sizzle while avoiding burn through; 4) at that voltage, fine tune your wire speed setting if you need to, and make other adjustments with the gun, with stick out length, travel speed, angles, rhythm in your weave pattern, etc. Learn about these adjustments by watching your weld puddle, and studying the weld after it cools. What do you (and others) think?
The miller calculator bewilders me: it turns up settings for given steel thicknesses that some of my past machines could not deliver, but I was able to weld them successfully. From memory, it required for 1/4" steel something like 200 amps. This is a notional example, but it captures the facts in general terms. I have been very successful welding this size steel with machines with 150 amps. My current Lincoln machine will weld 1/2" steel with 180 amps. I've only done it once on a bit of scrap for about thirty seconds, with a demo machine, (I don't run the large wire needed), but the results seemed OK. The miller calculator says this shouldn't work, by a long way. (Gward, don't tell Miller I question their products, please.)
Does the old "rule", one amp for every 1 thou of an inch of steel have any validity? I assume that if the rule has validity, then it is valid for all welding processes, not just stick welding (where I first heard about it).
My observation is that if the voltage setting is too high, you get burn through. If the amperage (wire speed) is too high, you just get bad welding.
The capacity of welding machines is determined by how many amps they can deliver.
So, a set of procedures for start-up welders would be (a suggestion for discussion, not a view set in concrete) 1) determine the thickness of the steel; 2) set the required wire speed to deliver the amps you need for your diameter wire; 3) set the voltage as high as you can to get the sizzle while avoiding burn through; 4) at that voltage, fine tune your wire speed setting if you need to, and make other adjustments with the gun, with stick out length, travel speed, angles, rhythm in your weave pattern, etc. Learn about these adjustments by watching your weld puddle, and studying the weld after it cools. What do you (and others) think?
The miller calculator bewilders me: it turns up settings for given steel thicknesses that some of my past machines could not deliver, but I was able to weld them successfully. From memory, it required for 1/4" steel something like 200 amps. This is a notional example, but it captures the facts in general terms. I have been very successful welding this size steel with machines with 150 amps. My current Lincoln machine will weld 1/2" steel with 180 amps. I've only done it once on a bit of scrap for about thirty seconds, with a demo machine, (I don't run the large wire needed), but the results seemed OK. The miller calculator says this shouldn't work, by a long way. (Gward, don't tell Miller I question their products, please.)
Thanks for all the information.
I have been welding fine on my settings, so I leave them as they are.
The best weld we find is having the voltage setting on 4, wire speed setting on 5 and current on 5. This is for a CEA Maxi 401 Mig welding machine.
I have been welding fine on my settings, so I leave them as they are.
The best weld we find is having the voltage setting on 4, wire speed setting on 5 and current on 5. This is for a CEA Maxi 401 Mig welding machine.
You put 250 amps of 6011 on 1/4 inch iron it's like using a cutting stick.
Turn the MIG welder up and adjust the wire speed while you weld.Read the puddle and listen to the frying.If it blows a hole ? GREAT ! Back it off a little and carry on !
Charts and numbers are bolechit. You stand out in the Arizona sun welding 150 degree steel or up in iceland when it's 35 below all that nonsense goes right out the window.
Read the puddle for heat and adjust the speed for sound and spatter.
Turn the MIG welder up and adjust the wire speed while you weld.Read the puddle and listen to the frying.If it blows a hole ? GREAT ! Back it off a little and carry on !
Charts and numbers are bolechit. You stand out in the Arizona sun welding 150 degree steel or up in iceland when it's 35 below all that nonsense goes right out the window.
Read the puddle for heat and adjust the speed for sound and spatter.
- Otto Nobedder
-
Weldmonger
-
Posts:
-
Joined:Thu Jan 06, 2011 11:40 pm
-
Location:Near New Orleans
James1000,
If what I've looked up so far is correct, this is a "synergic" MIG system?
All the answers I had are out the window. I'll have to dig a bit deeper.
Steve S
If what I've looked up so far is correct, this is a "synergic" MIG system?
All the answers I had are out the window. I'll have to dig a bit deeper.
Steve S
noddybrian
- noddybrian
-
Weldmonger
-
Posts:
-
Joined:Thu Jan 24, 2013 12:13 pm
In simple terms any Mig I've seen you set the voltage & then balance the wire speed to suit it - this wire speed & wire diameter then creates the effective current while welding - some wire speeds are loosely calibrated to indicate a current - I don't see how a machine accurately displays both ( maybe I'm wrong here ) - synergic is different in that most of the ones I've seen you need to specify the wire type & diameter - now you input the material thickness - the machine will now display a target amps that is whats programmed for that combination - the volts if shown are what it's determined will create that current to suit the material & will usually remain constant - the wire speed will however vary to attempt to maintain a constant current - there is often a + / - leaway adjustment for if you are not happy with the machines selection process - it's easier to use one than explain it .
noddybrian wrote:In simple terms any Mig I've seen you set the voltage & then balance the wire speed to suit it - this wire speed & wire diameter then creates the effective current while welding - some wire speeds are loosely calibrated to indicate a current - I don't see how a machine accurately displays both ( maybe I'm wrong here ) - synergic is different in that most of the ones I've seen you need to specify the wire type & diameter - now you input the material thickness - the machine will now display a target amps that is whats programmed for that combination - the volts if shown are what it's determined will create that current to suit the material & will usually remain constant - the wire speed will however vary to attempt to maintain a constant current - there is often a + / - leaway adjustment for if you are not happy with the machines selection process - it's easier to use one than explain it .
This all makes good sense to me. Surely, this approach will work.
Now, think of a beginner: they're looking, most likely, at a machine with two rocker switches marked 1, 2, and Hi and Lo. Or they might have an eight-point rotary switch. Wire speed dial has numbers, 1 - 10. No meters. And the welder manuals often do not have a table of the voltage outputs for each rocker setting (Hobart does, and its great, my Lincoln does not). Now, this beginner looks at a piece of steel, and chooses which voltage setting? And "why"?
With successful welding experience the choice is easy, and easily corrected, if necessary.
But every year I meet at least one person who states that he (always a "he") bought a mig welder because "mig welding is easy", and he gave it up because he couldn't get the hang of it, couldn't make a good weld. These have always been handy people, and they just lacked a reliable starting procedure to get past the first two months, in my view.
If the "amps first" approach, that I outlined, is valid, then the thickness of steel guides the beginner on wire speed, and then the rocker switches and half inch stick out help find the sizzle (best voltage setting), and again fine tune the wire speed if necessary.
I am not trying to be a dogmatic turkey, and really, I just want expert welders to clearly spell out a machine set up process that will reliably put the beginner into the "functioning but still has to improve" category before they give up. If its voltage before wire speed, that is fine. But we're not there yet.