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Up Topic Welding Industry / General Welding Discussion / Gas mixtures (locked)
- - By metalfab24 Date 01-10-2007 06:11
I weld for a company that builds mobile cement mixers.  Everything is MIG welded.  The company is phasing out old MIG welders.  The company is purchasing new Miller 350 MIG welders.  They are doing this so welders can be set to pulse welding.  They only want welders to weld in the pulse mode.  For what they are telling me, they want to pulse weld because the weld will produce LESS spatter.  Well I had a question about the gas mixtures they are using.  They are using 85% argon and 15% carbon dioxide.  Is this the correct gas mixture they should be using to produce the weld they want with pulse welding?  Should they be using 85% argon and 15% oxygen? I was just curious what the options might be here in this situation.  If someone could help me out with question I would greatly appreciate it.  Thank you...lets make some sparks!
Parent - By Blaster (***) Date 01-10-2007 06:25 Edited 01-10-2007 06:37
Off the top of my head, I think the Miller 350P pulse program parameters for steel GMAW are based on C10.
Parent - - By Lawrence (*****) Date 01-10-2007 07:03
Spatter free  spray transfer mig with 15% C02 Ar balence is common with or without Pulsation.

Lots of folks spend money on expensive pulsers when all they really need is somebody that understands process control to set production parameters.  If your welding with an old fashioned CV Mig in the flat or horizontal fillet positions on plain carbon steel and spatter is a problem it's a case of poor production management.  Excellent results should be gained with or without pulsation. (depending on the pulse unit, many are lemons that are not able to procuce as advertized)

To answer your question... Your 350-P (assuming that is what you have) should be able to pulse well with a variety of gasses.  If the machine does not come with pre-programmed parameter slections that work well with your gas mix than your Miller electric rep can download pre-set parameters for the gas you mentioned.

Millermatic 350-P is an excellent pulser
Miller XMT 350 is a dog of a pulser

Which do you have?
Parent - - By MDG Custom Weld (***) Date 01-10-2007 14:09
I think you hit it on the head Lawrence.  Most manufacturing companies think of mig welding as something you have a welder turn on and run.  Spatter is almost always related to poor set up.  Most power supply manufactures try to push things like pulse or gas mix as the smoking gun and almost never help the customer to optimize procedures using the existing equipment.  After all, they want to sell machines!
Try doing some parameter development to make the system you are using weld with little or no spatter.  It might take many hours, but even 1970's power supplies can still weld good if they are set up properly.
Parent - By dmilesdot (**) Date 01-10-2007 15:24
From what I remember about doing repairs to cement mixers the problem lies with the chemicals that the steel inside the mixer is exposed to.  There was some chemical that was used to clean out the mixers that was incompatable with mig welding.
Parent - - By SWP (**) Date 01-10-2007 15:35
To answer one of your questions, no you would not want to us 15% Oxygen, the normal recommendation for Ar/O2 is 1 to 8%.
I worked with PGMAW of steel with 8 to 10% CO2 for a number of years.  To be honest, I started out using a pulsed spray mode and did not attempt non-pulsed spray, I already had pulsed so I used it.
For the question of spatter, in my experience with relatively thin parts, around 1/8" thickness, I had to run a rather tight arc/low voltage to get good consistent fusion and bead appearance, particularly where the joint was narrow and deep.  With the tight arc you get some spatter, but thats was the price for a good weld.  In some cases the material thickness and joint would allow an increase in amperage and voltage, and I could get good fusion with the more traditional spatterless spray associated with longer arc length.

If you can wade through a ton of opinionated commentary, you might find some good info from Ed Craig.  From what little I've gathered, he claims that PGMAW is a waste, a consiracy of the manufactures to sell new machines, and that anything suitable for GMAW need can be done non-pulsed.  This may be true for heavy section flat position welding, but from personal experience with PGMAW in orbital pipe welding, other out-of-position welding, and thin section welding, PGMAW can accomplish welds that are not possible by conventional spray GMAW.

A good source for info on GMAW gases can be found in this AWS article, GMAW Best Practices, Feb. 2006 WJ.
http://files.aws.org/wj/2006/02/wj200602/wj200602-46.pdf
Parent - By Lawrence (*****) Date 01-10-2007 15:54
Stanley

Ol Ed Craig has actually changed his tune on at least one GMAW-P power supply. 

He now endorses the MillerMatic 350-P 

I very much agree with Ed on this one... it performs as well or better than power supplies at thrice the cost.

It is the only Miller pulse unit I really like unless you have special needs that can be addressed by the Axcess and RMD.
Parent - - By jarsanb (***) Date 01-10-2007 16:35
Very good input, well said. As an add on regarding the spatter issue, the higher the co2 content the higher the voltage values will be regarding the transition current. Many within Miller do recommend a 98Ar-8CO2 mixture for their pulsing equipment (given the application). Dropping the CO2 percentage may allow you to lower voltage resulting in less spatter.
Parent - By Aldridge6670 (*) Date 01-12-2007 13:26
to much platter  clean it up with a chisle   or set the wire speed faster than the volts at my work we have the miller delta welds  fair machines   welding 3/8   run it at 22 and wire speed at 6  if critical I'll even lightly spray with anti splatter  in flat position or down hill    very little B B's   I do production work for alot of CATipiller parts  were they have to be burr free and neat  ''perfect'' welds and alot of them   Pulse is only good for TIG    thats truely my opuion 
Up Topic Welding Industry / General Welding Discussion / Gas mixtures (locked)

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