Spray transfer mig questions

[farmboy weldor]

ive got a few questions, does it offer any advantages, and is there a cut off point to where i should start using it metal thickness wise?

and should i get wire larger than .035 or can i stay with that size of a wire?

i picked up that spray transfer just creates a nicer bead appearence and not much else, am i wrong?

if anyone could just give a kind of specific explanation of spray arc transfer it would be great.

thanx for any info

[B2n3 welder]

I'd say each process has its unique look as far as bead appearance but spray offers less splatter,but its used on thicker material. The heat it makes will really distort metal i would say 1/4 inch thick or more would be good for spray transfer.

[hankj]

Spray transfer on material > .250 is a desirable process. It delivers very good heat to the weldment, and the bead profile is very clean. Is it virtually spatter free, and it sounds neat, too!

If you have a machine that is spray capable, you should certainly consider it!

Hank

[MAC702]

Farmboy, what MIG do you have?

[farmboy weldor]

mac i have the mm251 right now , and this is kinda of topic for this post but can the passport weld fluxcored ,

thanx for any info

[hankj]

Farmboy,

Your 251 will spray with gases like 90/10, 85/15, 98/2, etc. Almost any high argon concentration will spray with that unit.

The Passport is rated for fux-core.

Hank

[BCarlucci]

with your 251 i'd run the 90/10 gas or 98/2, so that way your not running your machine at the higher end. and i agree with hank, 1/4" and thicker is where you want to use spray, any thing thinner and your metal's going to look like wave form.

[stinkinlincoln]

I use an MM251 at work. We run .035 wire with T54 gas. That setup can easily weld 1/2". Occasionally, we make preheated multipass fillets on 5" plate and thicker with that setup. It's not ideal but it works good. Make sure your wire is feeding smoothly and you use a long stickout (1" or more) or you will burn tips all the time. A good spray arc setup really really increases the effectiveness of a mig welder.

[HAWK]

with your 251 i'd run the 90/10 gas or 98/2, so that way your not running your machine at the higher end. and i agree with hank, 1/4" and thicker is where you want to use spray, any thing thinner and your metal's going to look like wave form.

I fab a lot of 1/8" to 1/4" material with 92Ar/8CO2 shileing gas, .035" wire, 28.5 volts and 345 ipm wfs with excellent results-no sine waves with this process. I also wet out the puddle considerably witth 40%-50% inductance.

[kejohnson]

Confined Area

I know that normally spray arc is acheived with higher Argon concentrations, but it seems like my MM251 will sometimes start to spray when I am welding in a confined corner. For example on one of our saddle racks, 3 of the sides are closed in a smaller area (Kinda like 1" angle iron on top of each other). I am normally doing short circuit with 75/25 (.030), but when I work in these confined areas the sound changes, it doesn't appear to be short circuiting, and the weld is great. I am just curious if the confined area is allowing the argon to spray even with 75/25?

[jedd]

Your 251 will spray with gases like 90/10, 85/15, 98/2, etc. Almost any high argon concentration will spray with that unit.

1) So, the spray technique is primarily based on selection of gas shielding ? Nothing to do w/ welding skills, or different settings ?

2) Can A MM251 spray w/ C25 gas ?

[hankj]

You need to be running at higher arc voltages to get into spray. The 251 ia capable of 28 arc volts. You can get into spray with .030 wire ~26 arc volts at a pretty high wire feed speed. On my 210, it's tap 7 and 80. The higher the arc voltage, the less argon you need in the mix, but I don't believe 75% is enough argon fo spray. 90/10 would work, and 98/2 will fefiitely work.

As for skills, you need to be able to hold a higer travel speed. Ole' shaky here has some trouble with that, but otherwise, I can do it!

Hank

[gascart]

The Miller pulsed mig handbook says that globular transfer starts at around 22 volts, and spray transfer starts at around 24 volts for mild steel.

The volt/amp curve on the 251 shows that it should be able to run 28 volts under typical welding loads, and around 26 volts at it's top end. So the answer to if the 251 can do spray transfer, is yes.

Also change the gun nozzle to one designed for spay, where the contact tip is recessed more, and run with a longer stickout than with short circuit.

Unfortunately the MM251 manual doesn't really address sray transfer, so you've got to look elsewhere for more information - especially with shielding gases and technique.

90% argon/10% Co2,
92% argon/8% Co2,
98-99% argon/1-2% o2
are listed for mild steel spray transfer in the Miller GMAW handbook.

92% argon/8% Co2 is a good dual purpose gas, as it works well in short circuit mode on clean steel also.

[Danny]

92% argon/8% Co2 is a good dual purpose gas, as it works well in short circuit mode on clean steel also.

75/25 is going to a much better general purpose short circuit transfer gas mix then a 92/8. The reduced CO2 content in the mix is going to increase the lack of fusion potential as material thickness increases. In short arc mode, 92/8 is going to be best suited for sheetmetal gauges. BTW, I ve ran a 251 in short arc mode with 90/10 and the results wasn t very good. 75/25 is definitely the mix to use for short arc with a 251.

[farmboy weldor]

where can you find voltage amd wire speed settings for spray or is it just gonna be a start at a voltage kind of thing and you have to fine tune it for yourself,
is just the kinda thing you have to do for yourself

thnx for the info