I'm ashamed to admit it , but my guns and liners get damaged from kinking and dropping stuff on them before i ever wear them out , such as dragging them around job sites and riding in the back of a service truck.
Replace your liner when you start having wire feeding problems.
The quickest way to ruin a liner is running dirty, rusty wire thru it which also falls in the abuse category.

 

Thanks for your reply
Is there any rule of thumb to change the liner when use a number of spool of wire?

 

And just about the time you think you've seen every possible way some one can bugger up a wire feeder system.....

Apparently some one was having feeding problems with this gun and thought the solution was to replace the liner. Problem was they really didn't know how to go about replacing a liner correctly and they cut it off about 3" to short. The wire ended up grabbing the liner and because it wasn't long enough to be butted up tight against the diffuser it had enough room to pull it out of the ferrule (this is on the machine end of the gun) leaving an area where the wire wasn't confined and supported. Then I guess they must have had a burn back to the contact tip and the drive rolls (being way over tightened) just corkscrewed up a bunch of wire into the gap where it wasn't running thru the liner.

 

Started out trying to weld with this gun one morning and probably didn't go more than an inch (or two) before I realized some thing wasn't right. Pulled the diffuser off and found this. My guess is that the person using this gun on the night shift before me was starting to have feed problems and he thought the answer was to keep tightening down on the set of knurled rollers that were installed on the feeder.

My fix was to pull the liner out, blow both it and the gun conduit the liner goes thru out, reinstall (the same liner) and back the roller tension off so it wasn't chewing up the wire. No problems with it the rest of the shift.

 

Blowing out your liner with every spool change is not a bad habit to get into. It's pretty easy thing to do to help insure everything keeps running smooth. But, IMPO those OSHA approved safety air nozzles are all but worthless for doing this. You need one of those old school air nozzles that put's out full flow, 100+ psi to really do any good.

 

Will high pressure damage the mig gun?

 

My Bernard gun uses that "Quick Liner" as shown. When the liner is trimmed back from new correctly it actually bears upon the diffuser compressing the liner a bit to keep it located correctly in the gun.

 

Thanks for every input

 

+1 on having a spare liner.

I would replace it if you suspect you have feeding problems. In our little shop we have a couple of Abicor-Binzel guns and I think we pay about $5 for original liners (for steel). Not a huge deal buying an extra or replacing it if you suspect problems with the liner.

You can test the liner by feeding the wire manually into the gun. There should be very little resistance.

 

Thanks for your advice

 

Punsg1,

I've used between 120 and 150 psi air to blow out a lot of liners / guns and can't recall ever causing any damage. You need to get the air nozzle right up against the end of the liner with as good of seal as possible. My procedure for blowing one out is to do it first from the nozzle end and then a second time from the feeder end. In heavy industrial environment it's not unusually to see a healthy puff of dirt come out of one when you do this.

You didn't say your exact circumstances but if it's just a home hobbyist type situation and you take reasonable care of your equipment and don't have any accidents that damage your gun conduit I should think a liner would last you dam near for ever.

 

Thanks

 

When cleaning my MIG gun liner in the past, I have given it a liberal spraying of anti-spatter spray then a blast of compressed air. Having a paper towel or rag at the end to catch what comes out let's you see how much good you are doing with the cleaning. Sometimes it helps to spray it 2-3 times(or more) followed each time with the air, to make sure it is completely clean.

 

You can release the drive rollers, and pull a few feet of wire out of the front of your gun. It should pull through fairly easily considering the weight of the wire on the spool. If it pulls fairly easily you are good for now. Several things can determine how long your liner will last. Copper Flake on cheap wire often but not limited to drive roll tension being too tight, Dirt, Rust etc. Always use a larger diameter liner than your wire. Just because you run .035 wire does not mean you have to run an .035 Liner. go bigger. The more bends in your gun during use, The more the wire drags on the liner walls. Learn to adjust wire tension so the drive rolls slip instead of birds nesting. That way you aren't elongating the wire before it goes into the gun. reach in and pinch the wire wire on the inlet guide side and feed wire. You should be able to make the drive rolls slip a little. Or tighten just enough to make the wire ball up in your hand.