MIG HELP

[BuiltnotBought]

Morning All,

So I have a question or two about some stuff, but first I though id give a quick machine spec and conditions material etc.

So I have a nice shiney new (because clearly someone is on my side) Miller XPS 350, running 1.2mm wire through a 24v wirefeed in a Parweld gun. Argo shield (not light) is piped in and I am cooking 8~10mm sheet to 25~30ish mm (reasonably think and frigging hot)

It's a 350Amp machine with 30 power settings, I am running it on the 27th power setting and a wire speed of around 5 (mpm? I assume its measured in meters per min!!?)

So the first question is how do I know when the duty cycle is about maxed? And the second and slightly more critical I feel is why the hell am I getting a glass like layer of something, flux mayne?, on the top of the weld. I've seen it in small amounts before but its almost like a glassy version of MMA

Any ideas would be greatfully received.

thanks in advance


Al

 

[BrokenBiker]

firstly, wire speed is normally measured in inches per minute, but if you are using a dial from 1-10 then it isn't worth trying to work in inches per minute.

you will know when the duty cycle is up because the welder will stop working

the glass like layer on your welds is silicon that has 'melted' out of the wire and settled on top of the puddle. There is no flux in normal mig wire

 

[Ed.]

On my Miller Auto Invision 456 with a S-62 wire feeder the dial has two ranges, metric and imperial, 1" to 8" inches x 100 per minute and 1-20m per minute. But it it welds OK then I would disregard what it says on the dial. Also, as you weld and exceed the duty cycle the amps will start dropping and you will be able to tell that something is not right as the wire will keep feeding at the set rate but you won't have the amps to weld properly.

Either way I think that your machine should have a temp warning light on the front panel which would light up if you exceed the duty cycle or get close to it, which by the way is 45% at 350A @ 31.5V.

From what I understand of your machine, it has imperial only in which case I would assume that it would be inches by 100 as a scale.
According to the documentation " If unit overheats, thermostat(s) opens, output stops, and cooling fan runs. Wait fifteen minutes for unit to cool. Reduce amperage or duty cycle before welding". So in other words if you exceed the duty cycle it stops until the welder cools down.

To exceed the duty cycle you would be doing some serious welding! on the 30mm plate yes you could, but on the 8-10mm with 1.2mm wire you would only be using up to 250-280A so I would assume that your duty cycle would increase quite a bit.
Here is a link to your machine, assuming it is the same one. Hope this helps

http://www.millerwelds.com/om/o249332a_mln.pdf

Cheers

Ed.

 

[BuiltnotBought]

Hi guys,

Thanks for the replies. I didnt beleive I had hit the duty cycle, it was more that it was new and I was unsure if I needed to do something specific when it got to it ... though I suppose reading the hand book would have been the obvious one

So regarding the shiney silicone? Its nothing to worry about!? Its funny, having read the replied its really obvious it wouldn't be flux but I just over looked that. Sorry for the stupid comment there!

What is it causing a significant increase of it? Is it something to expect all the time or does it normally burn off? Is it varied depending on penetration/heat and materal thickness etc!??

Thanks again

 

[BuiltnotBought]

On my Miller Auto Invision 456 with a S-62 wire feeder the dial has two ranges, metric and imperial, 1" to 8" inches x 100 per minute and 1-20m per minute. But it it welds OK then I would disregard what it says on the dial. Also, as you weld and exceed the duty cycle the amps will start dropping and you will be able to tell that something is not right as the wire will keep feeding at the set rate but you won't have the amps to weld properly.

Either way I think that your machine should have a temp warning light on the front panel which would light up if you exceed the duty cycle or get close to it, which by the way is 45% at 350A @ 31.5V.

From what I understand of your machine, it has imperial only in which case I would assume that it would be inches by 100 as a scale.
According to the documentation " If unit overheats, thermostat(s) opens, output stops, and cooling fan runs. Wait fifteen minutes for unit to cool. Reduce amperage or duty cycle before welding". So in other words if you exceed the duty cycle it stops until the welder cools down.

To exceed the duty cycle you would be doing some serious welding! on the 30mm plate yes you could, but on the 8-10mm with 1.2mm wire you would only be using up to 250-280A so I would assume that your duty cycle would increase quite a bit.
Here is a link to your machine, assuming it is the same one. Hope this helps

http://www.millerwelds.com/om/o249332a_mln.pdf

Cheers

Ed.

Hey Ed,

So you are pretty clued up on this it would seem ... that or you can read and recite info well I suppose

I had as it happened read the hand book and seen the duty cycle and voltage to amps charts on there.

Would it be fair to assume that when the welder has being going well and dandy and starts to act as though the wire speed is lacking that this is it reaching a near duty cycle maximum!? From the display on the front its drawing around 30.1 volts and spitting out aroubd the 280 amp mark. Though ironically on the power charts it implys this isn't possible. The curve is no where near these figures!.

Oh and you were also correct about the temp light on the front.

thanks again

Regards

Al

 

[Richard.]

There is probably silicon in the base material and heated silicon solidifies much slower than metal which is why it's pushed to the top .deeper penetrating processes tend to get this more. Are you using a high CO2 gas? 80/20 can reduce it also metal cored wire can help with this further. Cheap wires contain more silicon. Stick to a good brand.

 

[Ed.]

Hey Ed,

So you are pretty clued up on this it would seem ... that or you can read and recite info well I suppose

I had as it happened read the hand book and seen the duty cycle and voltage to amps charts on there.

Would it be fair to assume that when the welder has being going well and dandy and starts to act as though the wire speed is lacking that this is it reaching a near duty cycle maximum!? From the display on the front its drawing around 30.1 volts and spitting out aroubd the 280 amp mark. Though ironically on the power charts it implys this isn't possible. The curve is no where near these figures!.

Oh and you were also correct about the temp light on the front.

thanks again

Regards

Al

Hi Al, I don't know about the being clued up part, I did have a quick look at the manual to look at the specs before I put my foot in it, as Miller often puts a few models on the same brochure, and sometimes with different options, on Page 9 of the manual it shows your Amps vs Volts, however the duty cycle chart on the previous page shows the duty cycle for the larger 450 welder so that duty cycle chart doesn't apply to your model.

The only experience I have on Miller welding units is one I have, and I have never maxed it out as it does up to 600A@25%, 560A@60% duty cycle and 100%@450A and at those sort of amps I would need to use 1.6mm wire. So needless to say my unit gets a very easy life! as I even rarely use 1.2mm wire nowadays.

As for the wire speed when exceeding the duty cycle, the speed of the wire should stay the same but your weld bead will start going cold and could start to jump around or push the torch away as there won't be enough amps/volts available to melt the wire at the set speed. But I would not test that theory as exceeding the duty cycle may degrade the welder if the protection measures don't work as they should, having said that, constant welding for 4.5 minutes ( your duty cycle) at 350A is a very long, big weld and I would imagine the heat will be excessive, the steel your welding would probably start to distort/bend so most likely you would have to stop anyway either for a break or to move to another section to weld long before you got to max your duty cycle! Just my 2 cents worth!

Cheers

Ed.

 

[BuiltnotBought]

Evening All,
Appoligies for the slightly delayed reply. Apparently my email alerts weren't making it to me
Richard, regarding you comment on feed wires, that's interesting because I was originally using Esab stuff and recently my work shop manager / useless b***ard who I rely upon to order me stuff had a fall out with the supplier and changed to a different one. Might mention it to him and see if he will at least try a better brand. But back to the most important question of all ...

Does it matter?????


will it affect the weld in any way at all? or is it more cosmetic ?


Regards

Al

 

[Richard.]

Unless your going to paint it I would say no. Silicon is added to these wires as a deoxidising agent it also provides weldability. It's quite clever how it works because it takes the s##t out of the weld pool from the base and brings it to the top. The best way to eliminate them is with a metal core wire. If your gonna use esab the 46LS is such a super metal core. They are not causing you harm though.