problems with tip binding(mig)

Date 07-15-2005 04:45

Hi there all

I am having a great deal of problems with the Lincoln welding machine at work. Not sure if it is the wire, the tips, or what. Here is what is happening: after welding for a little while, when the tip and nozzle and gun are nice and hot, The wire seems to bind really(extremely) bad in the tip. You can feel it vibrating all the way down the line, and the wire coming out of the tip basically pulsates really fast, causing the arc to strobe, which in turn causes high heat in the nozzle and turns it red hot. I have tried cleaning the tip with a tip cleaner, but this seem to make it bind up faster. I have tried changing the tip oout and it is fine until I've been welding for a few minutes (10-15mins). This is getting very frustating as it is casuing a lot of down-time. I have asked the Journeyman and he cant help me at all. The other apprentice is experiencing the same thing. I have only been at this company for about 3 months, and it is the first place that I have used Praxair product. I have never had a problem like this before with Air Liquide, so I am not sure what to do. PLease help me.

Thank you in advance

By rsliker (*)

Date 07-15-2005 12:58

A little more information could be helpful.
What wire are you welding with? You mentioned Praxair, what is the product your referring to?
Here's a few things to look over:
(1) Check to be sure your equipment is sized properly. wire guides at the feeder, drive rolls, conduit liner, and tip should all be sized appropriate for the diameter of the wire.
(2) Sometimes a sligthly oversized tip will help reduce the problem you describe but it could be other things that are causing the trouble.
(3) Check connections and condition of your leads, be sure your set up with the correct polarity for the process your using.
(4) Also, check the tension on the wire spool to be sure that it can turn free and feed wire smoothly.

By mrcleanguy (*)

Date 07-19-2005 00:43

The wire is ER70S-6. We are weldind with spray transfer running about 25.5V and 250-300 speed. The welder is a Lincoln cv-300. I hope that this helps

Thank you

By rsliker (*)

Date 07-19-2005 15:27

I would guess from what you posted last, that the wire diameter is .045 and you say you checked all the previously mention suggestions.
I ask because there is no mention of checking the wire spool tension and I'm only assuming your using spools. If you are using coils, check to be sure the coil is properly seated in the coil dispensed. Sometimes loops of wire will slip down along side the coil and cause the wire to become snagged. If you can, have someone watch for this while your welding.
You might also check to be sure the gun your using is meant for running spray transfer.
Trying a heavy duty tip may help some but I get the sense that something else is working against you here.

By gyadon

Date 07-15-2005 14:55

Also check to make sure the liner is the right length. I have welder cut the liner short and not have it up into the diffuser and the set screw tight. A little more info might help.

Gary

By mrcleanguy (*)

Date 07-17-2005 16:34

Hi, All the drive rolls, liners, inlet tubes, etc. are the correct size. We are welding in spray transfer. I believe that the welder is a Lincoln cv300 we are running heat at around 25.4 and wire speed around 250-300. I will have to check on monday what the exact wire type is. I am wondering if maybe we could try going to a heavier-duty contact tip. If there is more info that you require, please let me know, and I will try to include it. Thank you

By SWP

Date 07-19-2005 18:06

Can you see that the contact tip is melted on the end, or does it look like the wire is arcing and melting the inside of the contact tip?
Is this a new welding application or did this problem just crop up, and it used to work fine?
Did you say what type of gas you are using?
I am wondering if possibly your arc length is excessive, causing the contact tip to overheat or the wire to begin to weld to the tip. Is it possible the arc is momentarily too long, just when you strike the arc, or when you shut off the weld? Some welding systems have arc start and wire burn back settings that affect arc length at the weld start and stop.
Is the arc length excessive during the entire weld? If the sound of the spray is totally smooth, hissing, without any crackle, it may be too long of an arc, ie, voltage setting too high or tip to work distance too long. If the wire is 0.045, then I think the wire speed of 250 to 300 ipm may be low for a voltage of 25.4 V. I could be mistaken for your particular setup and power supply, but I have run a pulsed power supply in an automated machine with 0.045 E70S-6, 92 Argon/ 8 CO2, 400 ipm, tip to work distance of 5/8", and achieved a slightly crackling spray transfer, with a very tight arc length, and a voltage reading of around 25 V.
Hope this gives you some ideas.

By mrcleanguy (*)

Date 07-24-2005 03:57

Hi there

I have just started working in this shop about 4 months ago, but I think that you may have enswered the "?". I think that quite possibly the arc length is to long. The arc sound very smooth, with a hissing, and the occasional crackle as you move the arc back into the puddle. I will try to increase the wire speed slightly and see what happens then.

Thank you for your advice

By rsliker (*)

Date 07-26-2005 14:35

You mentioned before that you were welding in spray transfer.
The hissing sound you hear is an indicator of spray transfer mode.
You haven't said whether or not your welding work requires following a specific weld procedure (WPS) but before you make adjustments to the wire speed, you should understand that this will affect the amperage your welding with. I suggest you ask someone you feel is knowledgeable if your supposed to be following a welding procedure specification (WPS) and if so, what the range of variables are for volts, amps, and travel speed. RS

By BMcB63 Date 07-19-2005 18:31

My past experience with this problem is either the liner is in need of changing or too small, cut wrong, the drive rolls are too loose causing slippage. Also the tension on the payoff could be to tight.

Bill