Contact tip

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Why does my contact tip clog up and turn black after about 2 minutes of welding. It is a BRAND NEW contact tip and it turns black in about 2 minutes of welding Then after that it clogs upHow can I prevent this?Please help.-garrett
Reply:Are you using bare wire with gas or flux core?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RAre you using bare wire with gas or flux core?David
Reply:How dose it run for the first 2 minutes? Check your wire feeder make sure that it’s not grounded to the power source. It sounds like your grounded inside your tip.
Reply:Are you sure you have good gas flow?At least 15 Cfh?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:I don't have that problem although is their is any paint or dirt on the material this can happen. I have a little stainless brush that I use to brush the tip with every once and awhile and I also use anti splatter paste. I just stick the whole nozzle in just a little when it hot. shake off the extra and start welding again. Now that I think about it, using the paste this way will cause some blackening at the start of the weld. Do you follow this practice.Miller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:Also, make sure you are grinding off he mill scale at your weld joint.Miller Syncrowave 200Hobart Handler 140Thermal Dynamics Cutmaster 38E-Z Tube BenderPlasma Cam DHC2
Reply:I wonder if your liner is wore out or if it got messed up and is shaving your wire and then it builds up at the end and clogs up. Try changing your liner. --Gol'
Reply:Is your wire speed too slow for the voltage being used?City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:I have seen if the contact tip is not screwed in tight and making good contact with the gas diffuser it will overheat from resistance heating at the threads and oxidize the tip a black color.  The contact tip get so hot, it remains hot enough to oxidize after the shield gas stops flowing.  This overheating will also cause wire feeding problems because the copper becomes soft and galls on the steel wire.Also, are you using the correct tip size for the wire?  I've read many people talk about using the next size larger tip for a given wire, like 0.035" tip for 0.030" wire.  This does not make sense to me, I guess you may get good contact in the oversized tip if the wire has a tight cast (free loop diameter), but the tips are made for a certain size wire, and if the tip is too big, you'll have poor contact and arcing and melting inside the contact tip.I had a similar problem with automated MIG machines running 1000 lbs spools of wire.  The wire had almost no cast at all, a cut length of it would lay out almost perfectly straight.  The machine torch was also straight (not a goose neck) so wire did make good contact inside the tip, so the arc was erratic and the tips overheated and arc/melted inside.  We checked the cast on all our wire, and ended up sending several new 1000 lb spools back to the manufacturer.  We agreed on a cast specification with the supplier and that was the end of the problem.