setting MIG transfer mode - spray, dip/short-circuit

Hello all
Started learning MIG welding at last.
(done oxy-acet, TIG-stainless, stick/SMA before)
Have some questions already...
The transfer mode
When looking on the Web you come across Ed Craig's "Weldreality" site
which is mainly about MIG welding. His main topic is being
escoriating about people who don't know what mode they are aiming to
get and knowing very clearly what range of (voltage,
current/wire-feed-speed) puts you firmly in the middle of each
transfer mode.
So what do you reckon about being in "short circuit transfer" and
"spray transfer"? If those are good questions, what can you say about
each and where and why you would each one?
"Google" found me this on the public area of The Welding Institute
(TWI) site:
For 0.8mm (0.030inch) wire, which is in all machines at the college
spray | 150A to 250A | 25V to 33V
dip | 45A to 180A | 17V to 22V
Then other information is found on the Web is about the effect of
shielding gas. One suggestion is if want to be in spray, use
different shielding gas like Ar/5%O2, rather than the Ar/25%CO2 which
is in general use, including at the college.
Basically, want to ask - would it be a good thing to do to literally
set a machine to say 28V and 180A to observe what you get? As at a
college, want to make sure I am asking something reasonable if I ask
the instructor if it is OK to try this (1 instructor, >10 students,
so want to be reasonable!).
Any good places I could be looking, in books or on the Web, for
information?
Richard Smith
Reply to
Richard Smith
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There's several things that need to be taken into account in spray arc mode. One is to know if the machine is big enough to actually achieve it. Most machines like the Millermatic 210 just don't have the oomph to really get into spray arc mode. They max out at 28 volts which is marginal for spray without the proper gas mix. Another is the fact that if you happen to not set the wire speed high enough you'll probably fry the tip the first time you pull the trigger.
If you do try be sure to have a fairly heavy piece of metal to try it on. It will melt through thin stuff rather quickly.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
I think it would be reasonable for you to try lots of different voltage and wire speed settings, and see what kind of results you get. Also changing gas type, if you have a choice at school. I would also try dual shield wire if it is available at school. And ask the instructor too.
You may be getting ahead of the rest of the class. The instructor might be wanting to get everyone comfortable with short circuit transfer welding before going on to explain ( and demonstrate ) the other modes.
Dan
On my little machine at home, short circuit is good for thinner material. Spray with dual shield is better for thicker sections. ( More voltage, more current equals more power )
Richard Smith wrote:
Reply to
dcaster
Thanks Dan, Wayne
Have to admit got gas composition wrong. It's certainly Argon, 12% carbon dioxide, 2% oxygen
So claim of makers is that will allow spray transfer.
I will set the wire feed speed high first and come down, following Wayne's advice about high voltage for spray but low wire feed speed would lead to immediate burn-back to tip.
Thanks
Richard Smith
Reply to
Richard Smith
Anything with 85% or more argon will do spray arc. The more argon the less voltage needed to get into spray mode. Mines setup where I can adjust my mixture between argon and co2 as needed.
It's the safer way to do it alright.
Wayne Cook Shamrock, TX
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Reply to
Wayne Cook
The one to avoid is pure CO2. Most mixes will permit spray transfer, given a decent sized welder.
I'm a good amateur welder, but would only be a mediocre professional. When I'm teaching friends to weld or handing out advice on uk.rusty-car then I have two simple rules for learning:
- Don't use pure CO2. I know it's popular in the UK, but spend the money and don't use the freebie pub gas
- Use the "Spinal Tap" setting procedure. All the dials up to eleven, then learn the manual skill needed to weld before you even think about turning things down.
It's often thought (especially by gas welders) that turning up wire feed will reduce the heat and prevent spray transfer. However this also increases the charge carriers available and thus _increases_ the heat. Turning the wire feed up is often the fix many people are looking for but never realise - you may even turn the voltage down a bit, so long as the wire's feeding.
Most UK "domestic" welders, except the tiniest, _will_ happily run in spray transfer mode, so long as you turn them right up.
Reply to
Andy Dingley
The link I posted about the Military handbook has good graphs showing the setting ranges for all modes of transfer.
A mix of Argon 90% / Co2 10% Should get you into the spray mode.
John Noon
Reply to
John Noon
I was going to comment on wire speed from my experiences learning to use spray. I cranked up the volts but didn't speed up the wire and melted the tip and shield of my torch.
When adjusted right, spray is great for thick stuff. You can put down a lot of metal with very little splatter quickly. It also is quite a bit quieter than short circuit.
Steve
Richard Smith wrote:
Reply to
Steve Smith
Ed Craig also has a lot to say about expensive welding gas mixtures. He recommends a higher argon mix, like 87/13 argon/CO2 for spray. I've found this mix sprays at a little lower voltage, seems easier to set up than 75/25. Understand, I have no training, just trying to figure things out.
Steve
Richard Smith wrote:
Reply to
Steve Smith
Hi again - coming back on my own post.
Have now experienced spray on solid-wire MIG.
An instructor showed us, then we had a play. None of us had seen spray transfer before. If I recall right, a whistling, hissing sound and that incredible small cone arc. With fifteen minutes to end of day, we played quickly on one machine, taking it in turns. Ended up with a very overheated contactor tip. Kept it for posterity and it is on my desk now. Found out this:
- for dip transfer you have the contactor tip level with the end of or slightly protruding from the shroud
- with spray transfer the contactor tip needs to be recessed within the shroud.
Richard Smith
Reply to
Richard Smith

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