Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / General Welding Discussion / undercutting
- - By pat31 (*) Date 05-10-2007 22:12
i was wondering if anyone had some information on preventing undercutting,i have changed postions on the gun ,cut back on my voltage,i stil cant prevent the undercutting
Parent - - By Cole Welding (**) Date 05-10-2007 23:29
are you welding on pipe and structural material???
Parent - - By pat31 (*) Date 05-14-2007 02:56 Edited 05-14-2007 03:00
okay i do structural steel work i use .045 flux core wire we build casinos and wal-marts and so i basically use all types of material from channel to angel to wideflange beams.i weld on anything from 1/4"to 1 1/2"thick the amps are around 24.8 and wire speed around 315 to 340
Parent - - By Lawrence (*****) Date 05-14-2007 11:21 Edited 05-14-2007 11:33

Welcome to the Fourm.

A couple of things to think about.

We still can't give you specific answers because you haven't told us if your using self shielded electrodes or gas shielded. Although your parameters look like gas shielded to me.

A WPS can have a pretty wide range for voltage... Specific manufacturers recommendations are almost always within your procedures "range" and will bring you much closer to the best operating parameters.

With FCAW.. Keeping your stickout (contact tip to work distance) as close to manufacturers recommendations is also critical. If the flux is not properly pre-heated (too short stickout) or if the flux is over heated (too long stickout) your wire will not perform as it should.

If your FCAW wire is designed for a specific Gas and you stray from the Manufacturers guidelines you could cause problems like undercutting or worse.

Some FCAW wire is made to use 75/25 or CO2 100%... Most will provide seperate suggested parameter ranges for both gasses.

Finally, If you are using E70T-X wire to weld out of positon (other than flat and horizontal fillets) you will run into problems.
The above link is to a good example of a manufacturers guide for FCAW wire. Note the difference in voltage settings for different gas and that the parameters for Vert and Overhead welding are going to have to be more closely followed for maximum performance.  You may find that different manufactures suggest different ranges for the same wire diameter and designation.

I generally play it safe when running FCAW and use a 10 degree drag travel angle for flat, horizontal and overhead positions and about a 5-10 degree push travel angle for Vert with upward progresson.

Others may have more to tell.
Parent - - By pat31 (*) Date 05-14-2007 22:17 Edited 05-14-2007 22:20
thanks for the help i really appreciate it. i use 75/25 gas,i am kinda new at this,i have only been welding professionally for 4 years.i really appreciate the responeses
Parent - By Lawrence (*****) Date 05-14-2007 22:54
Let us know how it comes out!
Parent - - By ZCat (***) Date 05-10-2007 23:35
Definitely gonna have to supply a little more info. If you're talking about DualShield, try pushing the gun instead of dragging it.
Parent - - By Cole Welding (**) Date 05-11-2007 00:44
oh yeah!!!!!!! if you are welding on I bean or channel iron you may not be wanting on the sides long enough...  now on pipe you have to either run stringers or you going to fast tring to fill your bevel
Parent - By js55 (*****) Date 05-11-2007 13:33
There are a whole lot of causes for undercut. You need to provide more specifics as to your welding process, your joint, your position, your progression, your material, etc.
Parent - - By reddoggoose (**) Date 05-11-2007 16:33
Js55 is correct. Undercutting can be attributed to several factors: electrode angle, excessive travel speeds, excessive voltage and or amperage, base material that is too hot, and technique. Too really help we need to know what welding process, how many amps and volts, and joint geometery and welding position.
Parent - - By Kix (****) Date 05-15-2007 15:53 Edited 05-15-2007 15:56
How clean is the steel your are welding on?  Do you grind or wire brush it before welding?  If it's real rusty it makes the puddle real runny and will cause undercut and a real convex bead.  The clean the steel the better it will weld!!!!  I know fluxcore has cleaning agents and deoxidizers in it, but i don't care.  If your welding on rust it welds crappy as all get out!!!  The company probably bought you some standard fluxcore wire meeting postion and tensile requirements that welds best on clean metal. There are wires out there for crappy condition welding, but they're probably a bit more expensive.
Parent - - By pat31 (*) Date 05-16-2007 00:22
the steel is clean when i weld, as a rule i always clean my work piece before welding,i not sure what type wire they buy,its is supposed to be the best,but then again i don't know.what do you suggest on the wire.
Parent - - By aevald (*****) Date 05-16-2007 00:42
Hello pat31, you said in one of your responses that you were using 75/25 shielding gas, do you know if the wire that you are using is designed for this shielding gas? Some of the flux-cored dualshield wires are designed to be run with CO2 only, others are designed to be run with 75/25 only, still others are designed to be run with either gas, and recently there are a group of wires that specify using 90/10 for a shielding gas. There could be some small weld bead characteristics that might be noticeable by using the incorrect gas/gases for a specific wire, possibly undercutting might be one of those characteristics. There can also be mechanical problems associated with using the incorrect shielding gas for a specific type of wire. Weld deposits can be prone to cracking due to bead hardness, impact values for weld metal deposits can be affected by incorrect gases also. See if you can find an electrode identification booklet that might have the wire that you are using in it and verify that your machine parameters and gas type match what is called out for by the manufacturer. Good luck and regards, aevald
Parent - - By ZCat (***) Date 05-16-2007 02:30
You are welding too cold, for one thing. For .045 wire on structural steel, you need to be up around at least 28 on the volts. you want enough wire to get the arc to make a soft ssshh-ing sound. pops or crackles.
On a flat fillet weld, you need to push the gun, if you are dragging the gun you are gonna get undercut pretty much every time. Turn it up hot and push it.That's what fluxcore is all about, hot and fast.
For a vertical on the thinner stuff, you may have to turn it down a tad, but not all the way down to 24.8. The guys in Anchorage used to weld everything on 29 or 30 volts, even the thin angle.
I used to weld rollout welds on pipe at 32 volts and 550 wire speed. The welds looked like glass, they were that slick.
Parent - By jim parker (**) Date 06-06-2007 01:46
I,ve  ran .045 flux core wire for 9 years now. One thing i see all new wire welders do wrong is they travel or weave to fast! The key is smoth and steady! travle to fast up hill and it will lump up and undercut or even fall out!
Up Topic Welding Industry / General Welding Discussion / undercutting

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill