Miller Syncrowave 250 - Low Current Performance

[Fix Until Broke]

I've got a Miller Syncrowave 250 and was trying to weld the tubes on an aluminum radiator this weekend and ran into a problem where the initial startup current was much higher than I wanted. I would set the max current to 20 amps, but get 40-50 amps on arc initiation which would blow a hole in the tube .

Once an arc is established, it will run down to 5 amps (I need about 12-15 amps to get a good puddle and weld), but the startup is killing me.

I'm using a 0.040" tungsten, straight argon at ~15cfh, good ground via a clean steel table with the radiator directly on the table.

The tube is only about 0.020" thick so it's delicate work. Once I get some filler deposited, then it's not much of a problem since there's enough thermal mass there to absorb the startup energy, but it ***** to have a small hole to fill, then make it bigger due to the start arc, just to have to fill it back in.

Does anyone have any suggestions how to minimize this?

 

[ericlar80]

Strike your arc on a scrap piece of steel or thicker aluminum next to the section you are looking to weld then carry it over to where your weld is.

 

[ericlar80]

Here is an example, but in reverse. Ideally you use the different material so that it doesn't weld together.

 

[Fix Until Broke]

Thanks - I'll give that a try next time with a little "pre flow" gas purge so when I move the torch I've got a decent atmosphere in the area.

Maybe more to the root cause of the problem - is there something with what I'm doing or a limitation of the machine or maybe just the physics of initiating an arc that make this happen?

Was just reading some info on Lincoln's Micro Start TIG which sound like what I'm looking for.

https://www.lincolnelectric.com/en-us/support/process-and-theory/Pages/micro-start-tig-detail.aspx

Again, it's just the start, once there's an arc, I can modulate the current to clean the surface, make the puddle do what I want, freeze it, re-melt it, etc no problem (though the 1/16" filler is a hassle!).

 

[ericlar80]

Is there a dial on that machine labeled "initial A" for amperage? If so, you should be able to dial that down to as low as 3. Check out page 44 of this manual:
https://www.millerwelds.com/files/owners-manuals/O363AF_MIL.pdf

 

[Fix Until Broke]

I think that is just for the pulser, which I'm not using. I'll double check that it's turned down all the way.