Tri mix

By Lawrence (*****)

Date 10-04-2004 18:54

Hey Z5

Need more data from you to be most helpful.

But here are a few facts;

For mild carbon steel you will never need anything other than an Argon CO2 mix and the correct parameters for short circuit or spray transfer modes that will provide the highest productivity rates and mechanicals to meet any code.

Adding oxygen to the gas mix for spray transfer mode offers greater puddle surface fluidity, however, who needs more fluidity in a spray transfer bead?

Look at what Ed Craig has to say about the whole matter.
http://weldreality.com/MIG_welding_gases.htm

By z5gxray (*)

Date 10-05-2004 12:24

Lawrence,

Thanks for your help. the main reason for this question is because one of our vendors uses this gas mix and I need to know if there are any strength problems as we use 96AR/14O2. All of our welding is on 11ga. 1/4 to 3/8 mild.

By jfolk

Date 10-05-2004 13:58

Z5,

Are your welding procedures qualified to a code or standard? If they are make sure your wps allows intermixing of percentages of gases and compositions. Most codes or standards consider gases and mixes essential variables and either require re-qualification or hold strict percentage limits.

John Folk

By sparx

Date 10-05-2004 12:28

While it is true that you can take care of all of your welding needs on carbon steel with basically one gas, there are some advantages to adding a bit of oxygen to the mix. With the lower transition current required for ionization, the puddle forms at a lower arc voltage. I found though, that if you are welding a filet, the puddle will actually climb the vertical web a bit, which will not only help in better wetting, but can also reduce undercut. There is a lot of controversy over whether the gas companies are "gouging" their customers with these "ultra" mixes and many describe it as "smoke and mirrors", but in the real world, there are advantages to these products. If it wasn't worth the effort, the gas companies would not be spending the money to test and market these products.
As stated above, more information is required before an educated answer can be given.
regards
Sparx

By z5gxray (*)

Date 10-05-2004 12:58

The other variables are, gas is 90AR/5CO/4CO2 with lincoln L-50 and proccess is pulse GMAW. Are there any added advantages of spatter reduction by adding O2 to the mix?

By Lawrence (*****)

Date 10-05-2004 17:13

z5

I'm a little confused, in the above posts you have said your current gas selection is 96AR/14O2 (110%) ?? and in another post 90AR/5CO/4CO2 (99%) but what is 5CO??

With the L50 I'm also wondering why pulse? are you welding in the "vertical up" or overhead positions with spray transfer?

Also is this a semi automatic or robotic application?

If your welds are in the flat or horizontal positions and your in spray transfer mode their ought to be no spatter period. With argon/CO2 or a tri-mix. Furthermore, if in the flat or horizontal position the pulsed transfer produces a lower deposition rate than traditional spray transfer.

Both Lincoln and Miller pulsed powersources come with some pre programmed pulsed parameters, these parameters do require specific gas percentages to work properly.

So this is what we need to know;

Actual percentage of your current production gas mix?

Actual percentage of proposed changed tri-gas mix?

Type of pulsed power source?

Are you using pre-programed pulse parameters and If Yes are you using the gas that those parameters call for. (if your using a miller 60 series wire feeder or newer their should be an LED display under the cover that details wave shape, dwell times and pre-selected gas.)

Are you welding out of position (vertical or overhead)?

This sounds like its getting complecated but don't worry, if you can fill in the blanks here listed above things ought be become more simple.

By z5gxray (*)

Date 10-05-2004 17:53

Lawrence,
Sorry about the confusion,I should have had all of my facts right to start with. Our weld dept is currently using lincoln powerwaves and genesis robots, 86AR/14CO2, L-50. There are no vertical or overhead welds.
Another div of our company is overseas and uses the same power source and wire but there gas is 91AR/5CO2/4O2. We are trying to get all of our divisions on the same pace with increased productivity, minimal spatter, and high quality.

By Lawrence (*****)

Date 10-05-2004 19:58

Ok now were going places,

Powerwave is a nice machine, 86/14 sounds like a good gas selection to me. If burn through and sidewall fusion in fillits are not a problem it's the right choice. Spatter (if its your only problem) is more indicative of a need for parameter adjustment/process control.

Are there real quality problems or is this more like a company wide standardization of practices? (which is a good thing most of the time).

Are the powerwaves actually using the pulsed spray capabilities? Lots of folks buy these powersources but find in the end that more productivity is gained when the pulsation is switched off.

Are the workpieces ground clean or bead blasted? Mill scale can be a problem but your current gas selection should do well enough with or without it.

If pulsing. The factory pre-programmed wave shapes for each wire diameter have specific gas call outs. If you aren't using what Lincoln has called for you will need to tweak your pulse parameters. Lincoln has super customer support and I bet they would put you in the ballpark if you supplied them with; Your current gas, wire dia., travel speed, base material and thickness.

For spatter free arc starts on that robotic line your burnback settings will have to be right on too.

Again, Lincoln has been doing this a long time and ought to have this stuff right off the top of their heads. I was actually on the phone to the powerwave division at Lincoln last week and the guy I spoke to really knew his stuff and took his time making sure my trouble shooting was done well before he finished with me.

By z5gxray (*)

Date 10-06-2004 18:15

Thank you all,
I think you have answered all of my questions
Z5gxray.

By Lawrence (*****)

Date 10-06-2004 19:20

Let us know what your decision makers do and how it turns out on the floor.