Big Glob of Molten Metal

Hi,

I'm wondering if anyone can tell me why sometimes after I finish a bead of MIG welding the end of my wire has a big glob of molten metal left glowing on it, sometimes it continues to melt the wire back towards the metal and I have to hit the trigger to give it a bit more length..

Would it be too high a current for the wire speed? I've tried playing around with settings but sometimes it happens, sometimes it doesn't.

Is there a technical term other than 'glob of molten metal'

Thanks,

Duncan.

Reply to
DuncanM
Loading thread data ...

Short circuit transfer happens in cycle 20 to 250 times a second between wire electrically shorted in contact with puddle and arcing. While wire is arcing a big molten drop is forming on end. The arcing time is about 2 times longer than shorting time. So your more likely to have big solidified drop on wire end than wire stuck to work. Below about 22V wire feed welding is only short circuit transfer or globular with more spatter.

Globular transfer is always arcing with big drop forming on end of wire until it falls (gravity) into puddle. Globular transfer happens just short of spray transfer settings.

Reply to
R. Duncan

- snipped-for-privacy@bedfordvehicles.com (DuncanM) - spluttered in news: snipped-for-privacy@posting.google.com:

Most little migs are going to run with a 30 to 50 (of 100) wire speed, and heat at the #2 or #3 heat (of 4). If you're running with gas, it should probably be set around 20 (psi, I don't know what the inexpensive regulators measure with).

I see *bedford vehicles* in your handle, so UK settings might be a little different. Practice practice practice.

Reply to
Greg M

How's this for a theory. The arc stops when you loose the trigger but the wire feed has some inertia and continues to feed for a short time longer. This dips the wire into the weld pool as it is solidifying. Result is glob on wire. If the theory is right, there should be a matching hole in the end of the weld run. Is there? I have noticed it on my mig a few times but never really thought too much about it.

John

Reply to
John Manders

What MIG welder are you using? Big MIG welders MM251 for example have burn back adjustments inside on circuit board that keep wire feeding a little after power is off. I don't think 135 or 175 MIGs have that feature. Some also have a little preflow and adjustment on how fast feeder ramps up to speed.

Reply to
R. Duncan

Australia actually! I have the restoration of a Bedford Vehicle on the go.. you can see it online at:

formatting link
I'll up the gas flow a bit..

Cheers, Duncan

Reply to
DuncanM

Actually, I did back off the tension on the wire feeder, I wonder if the inertia of the roll is causing it to feed into the puddle after it's meant to have stopped.. I'll wind the tension back up a little.

I wont have time to get back out into the shed again until the weekend.. I'll let you know the result.

Cheers, Duncan.

Reply to
DuncanM

- snipped-for-privacy@bedfordvehicles.com (DuncanM) - spluttered in news: snipped-for-privacy@posting.google.com:

Goodness, it looks a bit like an IH( International Harvester) S-160 I owned a while back.

Luck though. ;)

Reply to
Greg M

I have a BOC MIG250C.. which probably means nothing to you, I dont know its an Australian brand or a rebadged one from somewhere else..

If you navigate to

formatting link
and drill down the product range you can find a spec sheet on it.. it says it has burnback adjustment so I'll have a play with that..

Cheers, Dunacn.

Reply to
DuncanM

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.