Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / General Welding Discussion / gmaw gas mixtures
- - By drshope (*) Date 07-09-2007 18:29
The company i am working for is considering changing the sheilding gas we use from 75 Argon/25 co2 to 90 argon/10 co2. We typicaly use .035 wire but will use .045 if needed. we do a lot of sheet metal welding. (7gage to 16 gage) We are realy concerned about asthetics of the welds. What are some of the pros and cons for using 90/10 gas mixture instead of 75/25?
Parent - - By Greg G. (**) Date 07-10-2007 00:02
Why change, I have welded sheet metal in that ga. range for a lot of years and it has always worked just fine for us. There must be some reason for this. Someone must be trying to make a sale. Better check the price.
Parent - By drshope (*) Date 07-10-2007 22:16
Greg,
I was not clear with my original post in that we use plate steel too (1/4" - 3/4" plate) The company wants to change due to the fact that you can run plate faster and with less spatter. My concern is the cost of requalifying all weld procedures currently in place. (We are using ASME section IX.) We Have 11 Weld procedures and 20+ welders that use them. That is quit a bit of time and money to requalify. I wonder if the savings would be worth the effort. Is their any other reason to change to 90/10 gas mixture? We are looking into a manifold system for our gas. That way we do not have individual tanks that each welder would have to change when empty. We would have a bank of gas that all the welders would hook into.  We would also save money on the gas by buying in bulk this way. Before we change to this system we would have to make sure of the type of gas we are going to use.
Parent - By gawelder (**) Date 07-10-2007 00:54
I use the 75/25 mixture also because the 90/10 cost more. The 90/10 mixture has less spatter.
                                                                                                                      gawelder
Parent - - By bozaktwo1 (***) Date 07-10-2007 23:19
We use 98/2 gas in all our steel GMAW welds.  It is my understanding that a variety of mixtures was tested, and the 98/2 made the better welds.  This was long before I was hired on.  Seems to work okay.
Parent - By Milton Gravitt (***) Date 07-10-2007 23:32
Yes I have used the 98/2 and it will do good on the thicker base metals but the 75/25 will leave a smaller weld on the thinner base metals. I have used the 90/10 before because the manufacture of the wire we where using suggested it. I have used 95/5 to and it does a good clean job to as for the splatter.
Parent - - By drshope (*) Date 07-11-2007 10:15
Do you use it on sheat steel? We are not having very good luck getting to short circuit mode for the lighter gages.
Parent - By Milton Gravitt (***) Date 07-11-2007 12:45
We use the 75/25 on the thinner sheet metals because you can reduce the heat alot more than you can with the 90/10 or 98/2.
Parent - - By DaveBoyer (*****) Date 07-11-2007 02:09
I think the reason for the change is probably so that they can use spray transfer on the heavier materials while still being able to use short circut on the sheetmetal. For reliable spray transfer one needs at least 80% argon.
Parent - By Tommyjoking (****) Date 07-11-2007 11:21
your right Dave...faster weld deposit with the more pure gas
Parent - - By 357max (***) Date 07-11-2007 14:06
If 80% or greater Argon mix is used and up to 90% both metal transfers (short circuit & spray) can be made. One gas - both transfers and if gage sheet metal is the predominant product; use the lower argon, if thicker metal is predominant; use the higher argon. Or, try out the various mixes and see which will have the greater operator appeal. Using a gas with more argon than the 75/25 will change the arc sound. If welders are setting short circuit metal transfer parameters based on the "Bacon Frying" sound, gas changes will make a sound/audible change. If the welder ain't happy, ain't nobody happy! Set the parameters with volts & amps and fine tune the arc with the inductance control.
Different gas distributors package different mixes such as: 80/20, 82/18, 83/17, 85/15, 87/13, 88/12 and 90/10 as standard offerings. The higher CO2 content will provide greater penetration in the short circuit transfer. The higher argon content will make it easier to achieve the spray transfer. How many gas distributors are vying for your business? They may lend you a cylinder for testing. Or, use a Smith Gas Mixer and mix your own.
Write the procedure with a specific gas percentage mix. Don't use the gas distributor's fancy dancy labels like Moon Gas 1 or Star Gas 3.
Parent - - By Kix (****) Date 07-11-2007 14:39
We are currently talking about making this change also from the 75/25 to the 90/10 instead of useing both.  The reason being that we can manage are gasses better, and you can short arc and spray with it.  We do a lot of metal core on thick steel with spray transfer as well as thin sheet metal with short arc solid wire.  This gas will short arc very well actually i come to find out.  You can run a good amount of wire into this puddle for good penetration for structural sheetmetal.  I don't have to worry as much about my guys and lack of fusion that a good looking weld with 75/25 can produce.  Not saying that you can't get lack of fusion with 90/10 , but the consistency of better fusion goes way up i feel.  A manifold system with welded fittings is the way to go if i was to do it my way.  We will go to a manifold system in the future, but this is going to have to do for now.
Parent - - By Greg G. (**) Date 07-11-2007 18:08
Check into the 6 packs. That way you can shut one of two bottles off and have them as a reserve.  This will give you time to order some more if you are not set up on a regular delivery route. Putting a complete manifold system in is very expensive. I priced it out one time. Also the welding supply outfit told me that they would not put the big tank outside because our usage was not high enough. They also told me that you would lose some just from being in the heat outside. Don't know if that is true or not, never got the outside tanks to find out. If you do the 6 packs it is a good ideal to keep some singles around so if you have to move the machine to weld in another area of the shop you can do so without moving the six pack.
Parent - - By Kix (****) Date 07-11-2007 18:47
I wonder why they said you would lose some because of the heat outside.  Thats kind of like saying bottle warmers do not help you get anymore out of your bottle witch they are suppose to do.  Thats a whole new topic there though.
Parent - - By Greg G. (**) Date 07-11-2007 21:41
I really don't remember the detailed information of why. I just remember the sales people telling me that. They said that if it sat for a period of time without being used,that you would lose some due to being outside.  Our welding machines weren't running 24/7 like some shops. Our welders did 100% of their own fit up. Someone else may be able to expound on that information more than I can. But that is what they told me. Maybe my salesman just didn't want to mess with it.
Parent - - By billvanderhoof (****) Date 07-12-2007 03:07
They may have been talking about liquid, which is at a very low temperature.  If liquid is left alone some small amout of heat will get in through the insulation and boil off some gas.  At some point if you don't use it it must be released to keep the pressure safe.
Bill
Parent - - By DaveBoyer (*****) Date 07-12-2007 03:15
Bill, I think You got it. The "big tank outside" would be a liquid tank.
Parent - - By Kix (****) Date 07-12-2007 14:33
Yeah thats what it is!! As the liquid becomes gas due to the heat the pressure builds and each tank has a PRV on it to keep the pressure at a constant and not build to unsafe pressures.  Anyone ever experiment with those bottle warmers to milk every last bit of gas out of your bottle?  I don't know how cost effective those things would really be.  I know they use them a lot on paintball air tanks and Co2 tanks.
Parent - - By aevald (*****) Date 07-12-2007 14:48
Hello Kix, I can tell you a funny story about bottle warming. One of my welding instructors was working in a fab shop many years ago and one of the fellas got the bright idea to see about getting a little bit more acetylene out of one of the bottles, so he put it on top of a hot plate. This particular type of bottle had a lead relief plug in the bottom of it as a safety for explosion prevention in case of fire. Needless to say, the lead plug melted and released the acetone and acetylene gas that was in the bottle and quite a little fire ensued. Fortunately this story had a somewhat happy ending in that no one was hurt and very little actual damage occured to the building or anything. All the guys in the shop learned a valuable lesson though. Maybe some of these types of bottle warmers are safe, however, I think I would probably shy away from them personally. Regards, aevald
Parent - - By Kix (****) Date 07-12-2007 17:58
They just look like a blanket that you wrap around the cylinder kind of like an electric heating blanket you would have at your house. They don't get hot enough to melt anything.
Parent - - By aevald (*****) Date 07-12-2007 18:37
Hello Kix, can I assume that these would be for liquified gases only and are they for Dewars or for high-pressure cylinders as well? This is the first time I have heard of this type of item and now you have me curious as to the applications and supposed benefits etc. Regards, Allan
Parent - By DaveBoyer (*****) Date 07-13-2007 04:10
CO2 is liquified in normal high pressure tanks, while other products are still in gas form. Gas will pretty much all come out on it's own at normal temperatures, but CO2 when it gets almoast all at high enough flow rates could boil off fast enough to drop the temperature too much to continue supplying gas. This is unlikely to happen in permanantly mounted liquid stations due to the size/volume, and fact that You would normally refill before it got near empty.
Parent - By Rslik Date 07-13-2007 17:50
You already have a lot of good info posted back to you questions but I'll try to add some if it will help. The higher percentage argon gases help reduce burn through by reducing arc energy. Co2 being a reactive gas adds energy when it breaks down and recombines during use. The higher the co2, the higher the arc energy thus the more heat generated at the arc. The argon, being a non reactive gas aids in arc stability which reduces spatter levels. Someone mentioned reduced penetration with higher argon percentages and that is one of the trade offs. 90/10 works very well with most metal core wires and is recomended by many of the cored wire manufacturers. We use it exclusively in our manifold system. In a large operation manifolds save a great deal of time and labor cost by not moving and changing cylinders. Bulk tanks do however bleed off some gas when the usage is low or stopped, as in weekend shut downs. Best thing to do before you decide, is try to determine the amount of arc time and use it to calculate the usage you have. Then have your supplier quote a bulk system sized slightly above your need, to allow for some increase in growth of your business. Most will install their tanks and your company will pay a " site fee "  or rental on the tanks. You would own the gas blender as it is usually located inside your facility. Blenders are adjustable  for a variety of mixes. You can ask for it to be preset for your preferred blend. RS
Up Topic Welding Industry / General Welding Discussion / gmaw gas mixtures

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill