Welding Tips and Tricks

Hi group, just wondering why my tungsten keeps discolouring when AC welding alloy, I have a UniMig Tig 200 AC/DC machine, new, just bought it, using Zirconium tungsten (white tip) just can’t keep tungsten clean on AC, it does ball up but only very small, I’ve clean the job real good and wipe over with acetone, using foot control, and while welding it crackles ever now and then, machine has AC balance, have tried adjusting but I haven’t gone too far either way with it, 10-80 balance adjustment but have only used it from 30-60, thought I’d post on here before I tried anything else. Tungsten goes a dark gray colour and looks a bit crusty and won’t ark when this happens. Thanks guys, cheers

Dennis Hrvatin wrote:machine has AC balance, have tried adjusting but I haven’t gone too far either way with it, 10-80 balance adjustment but have only used it from 30-60,

main thing is probably the temp the tungsten gets to and gas coverage while its hot.
heat is your amps you run and the balance. more cleaning action = hotter tungsten.
then its gas coverage, make sure stick out is not to long and you have long enough post flow to allow the tungsten to cool down before the gas is turned off. if your running high amps for the tungsten size it may pay to go up a size.

if the tungsten is to hot when the post flow turns off it will dis colour and go all crusty.

Thanks tweake, ok my post flow was very minimal, lol trying to save gas , I’ll up it see how i go, thanks mate

Dennis Hrvatin wrote:Thanks tweake, ok my post flow was very minimal, lol trying to save gas , I’ll up it see how i go, thanks mate

yeah i'm guilty of that to. gas is rather $$$$ here.

Yep, it's painful when you hear the gas flowing when you are paying for it. I wonder, just wonder, if you were to put the torch into a small, blind tube to cool down, you could reduce the flow time by creating a kind of purge environment....???

You need to set your AC balance to 65-75% EN, or equivalently 25-35% EP. It all depends how your particular machine is configured. At the moment it just sounds like you're trying settings out without really knowing what they are, based on your post. RTFM. And yes, it has a lot to do with tungsten temperature, as one extreme definitely heats up the tungsten more.

Oscar, increasing the post flow of gas has solved my problem of tungsten discolouring so I’m happy there. With the AC balance, 10-80, 80 being hotter on the tongsten, I will try what yes suggested, only thing I’m trying to work out now is why it crackles while welding on AC, almost sounds like a Mig weld and the ark seem to be wondering around , any suggestions on this?

Oscar wrote:You need to set your AC balance to 65-75% EN, or equivalently 25-35% EP. It all depends how your particular machine is configured. At the moment it just sounds like you're trying settings out without really knowing what they are, based on your post. RTFM. And yes, it has a lot to do with tungsten temperature, as one extreme definitely heats up the tungsten more.

Oscar, increasing the post flow of gas has solved my problem of tungsten discolouring so I’m happy there. With the AC balance, 10-80, 80 being hotter on the tongsten, I will try what yes suggested, only thing I’m trying to work out now is why it crackles while welding on AC, almost sounds like a Mig weld and the ark seem to be wondering around , any suggestions on this?
I have reg set on 15 I/min flow

You said you were "AC welding alloy", but you never actually said what you were trying to weld. What base metals are you trying to weld?

Dennis Hrvatin wrote:

Oscar wrote:You need to set your AC balance to 65-75% EN, or equivalently 25-35% EP. It all depends how your particular machine is configured. At the moment it just sounds like you're trying settings out without really knowing what they are, based on your post. RTFM. And yes, it has a lot to do with tungsten temperature, as one extreme definitely heats up the tungsten more.

Oscar, increasing the post flow of gas has solved my problem of tungsten discolouring so I’m happy there. With the AC balance, 10-80, 80 being hotter on the tongsten, I will try what yes suggested, only thing I’m trying to work out now is why it crackles while welding on AC, almost sounds like a Mig weld and the ark seem to be wondering around , any suggestions on this?
I have reg set on 15 I/min flow

It's a square wave machine which means it is going to crackle. Think of the square wave as trying to make a single tone out of beating a drum versus sine wave making a single tone out of blowing air through a flute. The drum beat is fast enough to make a frequency tone but you will hear the on/off of every cycle.

The important thing with white tungsten is keeping the entire rod clean. I'd smoothly grind down the sides as well until it is completely free from anything on it. Grind a new tip and then before you start welding, ball up the tip purposefully to the desired ball on a piece of scrap with a higher amperage and then come down on the amperage to do your welds. This means the ball will be big enough to sustain whatever abuse you are giving to the rod at your working amperage with respect to what AC balance you use.

I would start with 50% AC balance and then move it slightly towards the EP side of the balance. But again, you want a ball that can handle the abuse you plan to put it through in your welds, so I'd use a slightly higher % towards the EP side for balling it up, then bring the AC balance down to your working balance for your welds. If you are getting white coating on your aluminum it is probably due to not having enough EP balance. Slowly increase the balance towards the EP until the white coating disappears, given that you have 7-12 l/min gas flow. (Aluminum does better with more EP balance and less gas than 15 l/min gas and less EP)

(I guess I should say since you are using a foot pedal then the pedal should control all that but I was thinking for some reason of using the 2T settings. My bad)

Oscar wrote:You said you were "AC welding alloy", but you never actually said what you were trying to weld. What base metals are you trying to weld?

Maybe I should have said aluminium, I am getting my head around welding aluminuim, i have done a lot of Tig welding steel, moly tube, and stainless, but no aluminium so it’s new to me

trainingGrounds wrote:

Dennis Hrvatin wrote:

Oscar wrote:You need to set your AC balance to 65-75% EN, or equivalently 25-35% EP. It all depends how your particular machine is configured. At the moment it just sounds like you're trying settings out without really knowing what they are, based on your post. RTFM. And yes, it has a lot to do with tungsten temperature, as one extreme definitely heats up the tungsten more.

Oscar, increasing the post flow of gas has solved my problem of tungsten discolouring so I’m happy there. With the AC balance, 10-80, 80 being hotter on the tongsten, I will try what yes suggested, only thing I’m trying to work out now is why it crackles while welding on AC, almost sounds like a Mig weld and the ark seem to be wondering around , any suggestions on this?
I have reg set on 15 I/min flow

It's a square wave machine which means it is going to crackle. Think of the square wave as trying to make a single tone out of beating a drum versus sine wave making a single tone out of blowing air through a flute. The drum beat is fast enough to make a frequency tone but you will hear the on/off of every cycle.

The important thing with white tungsten is keeping the entire rod clean. I'd smoothly grind down the sides as well until it is completely free from anything on it. Grind a new tip and then before you start welding, ball up the tip purposefully to the desired ball on a piece of scrap with a higher amperage and then come down on the amperage to do your welds. This means the ball will be big enough to sustain whatever abuse you are giving to the rod at your working amperage with respect to what AC balance you use.

I would start with 50% AC balance and then move it slightly towards the EP side of the balance. But again, you want a ball that can handle the abuse you plan to put it through in your welds, so I'd use a slightly higher % towards the EP side for balling it up, then bring the AC balance down to your working balance for your welds. If you are getting white coating on your aluminum it is probably due to not having enough EP balance. Slowly increase the balance towards the EP until the white coating disappears, given that you have 7-12 l/min gas flow. (Aluminum does better with more EP balance and less gas than 15 l/min gas and less EP)

(I guess I should say since you are using a foot pedal then the pedal should control all that but I was thinking for some reason of using the 2T settings. My bad)

Thanks for the very useful info tG, I will give it a go and see how it goes. Thanks again, cheers mate

Things are coming together quite well, tungsten staying clean and welding is ok too, more practice and I’ll be there, thanks to you all who took the time to reply and help me out. A couple of pics

That's great. You won't have to have as much EP balance if you clean the weld area prior to welding. Too much EP balance may cause the aluminum to spit back onto the tungsten given enough amperage. For practice it's not necessary to clean the weld area but for production it's the only way to get consistency for a lot of welding and the best use out of the tungsten.

trainingGrounds wrote:That's great. You won't have to have as much EP balance if you clean the weld area prior to welding. Too much EP balance may cause the aluminum to spit back onto the tungsten given enough amperage. For practice it's not necessary to clean the weld area but for production it's the only way to get consistency for a lot of welding and the best use out of the tungsten.

Thanks tG, I ended up with 50% EP, went from a #8 cup to a #6, and the biggest diffence I found was going from a 0.8% Zirconium tungsten (white) to a 2% Lanthanated (blue), wow made a big difference, stays super clean and balls up perfectly, love it.
Had some pieces of 5052 alloy kicking around so I made a box last night for shits & giggles

Just have to work on the finish of the weld

Dennis Hrvatin wrote: Thanks tG, I ended up with 50% EP, went from a #8 cup to a #6, and the biggest diffence I found was going from a 0.8% Zirconium tungsten (white) to a 2% Lanthanated (blue), wow made a big difference, stays super clean and balls up perfectly, love it.
Had some pieces of 5052 alloy kicking around so I made a box last night for shits & giggles

Just have to work on the finish of the weld

Looks good, always used Zirconium for critical AL work, this was before inverters were common, now I use 2% lanthanated

Looks amazing. Nice work.