WIA welder porosity

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Ive been Mig welding for 20years and Im the guy you come to when your mig wont weld properly, but this one has me stumped. Ive been using this WIA (Welding Industries Australia) 205 remote for 4 years with no probs at all, but the last 6 months it has been having intermittent porosity problems. You can be laying down a perfect weld and it will start massive porosity for no reason. This was very intermittent but has been getting worse and worse so now it lasts days at a time. Of course I assumed it was a gas issue and cleaned, stripped the gun and liner, checked the regulator etc, etc. Ive replaced the regulator, replaced the entire handpiece, lead and liner, replaced the gas relay. Blown out all the lines (with relay open) checked all connections etc and eventually gave up and sent it to a Mig machine repairer who said it was the motherboard and charged me $1,200.00 Australian and it came back exactly the same! Its been stripped and cleaned many, many times, parts swapped off other machines to double check them, I'm running correct gas flow (not excessive) and there's adequate flow. When it's running right it welds beautifully but then... Clean steel (of course) .9mm BOC wire, BOC  Argoshield universal gas. Ive really covered everything but it still fails to weld nice, I'm beginning to thing it may not be gas flow but cant think of anything else that could cause this and I'm hoping someone out there might see what Ive missed.Cheers guysKymbo
Reply:So the thing to do is this: start at the tip of the gun and work your way back. Look for a split seal or small hole in the hose/ conduit. I had a Miller M25 that had come apart inside the handle and only misbehaved when in a certain position.Most likely it will be in the gun somwhere, Gas solenoid valve generally work or they don't. Internal leaks tend to be pretty rare.I also check the gun/machine interface for cut or missing o rings. I've also had problems with gas pressure being to high, not flow but pressure. This was keeping the solenoid from opening. A new regulator/flowmeter solved the problem. If you run a manifold sytem check your line pressure. We run at 80 PSI/ 5.5 bar. This seems to work pretty well for our shop of 10 stations.Good luck and keep us posted. Believe half of what you read and none of what you hear.
Reply:Are you using a gauge or flowmeter on your regulator. With a flowmeter, the next time you have the porosity problem, have an attendant moniter your gas flow. Then, at least you will know whether it is  a flow restriction, or atmosphere being drawn into the gun. Your situation is unusual in that the problem goes away and returns again. Any time I have had a similar problem it was usually the diffuser, or improper torch lead connection at the wire feeder. Good luck. Post your findings.
Reply:did you try different wire? might have contaminated wire or something contaminating your puddle like oil or a coating of some sort trying to burn off. Porosity is either a shielding problem or a contamination in either your wire or the metal being welded. How are you cleaning your steel for welding? Mill scale usually isnt a problem but I have seen porosity from it, Maybe your grinding wheel is leaving a residue or a cleaner is leaving a residue. Could be contaminated gas as well. Try and use a bottle of straight CO2 or a 25/75 CO2/argon mix. I dont know what the mix is that you are using but those are the two most common ones for welding steel. CO2 tends to be a little hotter but more spatter and slightly less pretty beads but it is cheaper. Mix gas makes a clean weld that looks nice but does cost more.
Reply:Solenoid might also be losing power and shutting off your shielding gas or the coil in the solenoid might be warming up and losing its holding ability to keep the gas flowing.
Reply:@ Dave. I stripped and cleaned/checked the gun and liner several times then bought a new lead and handpiece four months ago, it all made no difference so just this week I bought another new lead and handpiece just to try it out, still no joy. (new from machine to finger)@Pro-Fab. The machine originally had a contents gauge and flow gauge but when the trouble started I swapped another one off another machine I knew worked. It made no difference, when I had the same idea as you I took another gauge and proper flowmeter from my other machine and tried that. The gas flow, even when the machine is playing up is still quite normal.@Ironmangq. Ive had about four 15kg rolls of wire through this machine since the trouble started and at least three bottles of gas. I'm quite familiar with contamination problems with mig so I grind to bright steel, some of my steel comes grit blasted and a few times Ive even had trouble when Ive been making fuel tanks. When I make these I grind all steel edges bright/ sand all edges/ tack weld together/ grind leaders on all tacks/ wipe with thinners/ wipe with Acetone before welding. I stripped and cleaned the solenoid and recently put in a new one...just in caseTo All. You've had some great ideas here guys, but Ive tried all that and more. With 20 years in Fabrication Ive seen most Mig problems but not this one. Happy to hear your next ideas, Im sure it's something Ive overlooked. Thanks
Reply:Any grease or oil on the drive rollers?Earth clamp and lead in good nic?What's the porosity look like, is it just like lack of gas or ?
Reply:Might not be your problem but I have seen where a flap of burr ( for want of a better word) in a plastic or rubber air line can cause a blockage.  Flow causes it to swing into position and block the line.  Moves into a different place each time so result is variable/intermittent.You really have to "change this and see what happens" to isolate the cause.Gordie -- "I believe you understand what you think I said, but I'm not sure you realize that what you heard is not what I meant."
Reply:bad wire...looks like worm holes right?moisture got to the wire we had that prob with wire at the nuke plant when we were testing in and we found the wire was way out of date.After the arc has died the weld remains
Reply:Originally Posted by kymbo@ Dave. I stripped and cleaned/checked the gun and liner several times then bought a new lead and handpiece four months ago, it all made no difference so just this week I bought another new lead and handpiece just to try it out, still no joy. (new from machine to finger)@Pro-Fab. The machine originally had a contents gauge and flow gauge but when the trouble started I swapped another one off another machine I knew worked. It made no difference, when I had the same idea as you I took another gauge and proper flowmeter from my other machine and tried that. The gas flow, even when the machine is playing up is still quite normal.@Ironmangq. Ive had about four 15kg rolls of wire through this machine since the trouble started and at least three bottles of gas. I'm quite familiar with contamination problems with mig so I grind to bright steel, some of my steel comes grit blasted and a few times Ive even had trouble when Ive been making fuel tanks. When I make these I grind all steel edges bright/ sand all edges/ tack weld together/ grind leaders on all tacks/ wipe with thinners/ wipe with Acetone before welding. I stripped and cleaned the solenoid and recently put in a new one...just in caseTo All. You've had some great ideas here guys, but Ive tried all that and more. With 20 years in Fabrication Ive seen most Mig problems but not this one. Happy to hear your next ideas, Im sure it's something Ive overlooked. Thanks
Reply:sounds like a curly one ....you say it's a remote....have you checked the interconnect lead for kinks? ... had a similar problem with the weight of the lead/hose kinking the gas hose at the back of the feeder ... took ages to find - only closed up on warm days when the hose was pliable.anyway good luck chasing it..... nothing more annoyingJustin45+ years of accumulated fabrication junk - both physical and mental.....  occasionally some of it is vaguely useful.
Reply:@Wino Ive cleaned everything many times over including cleaning the rollers. (they accumulate muck and need regular cleaning in thins to prevent them spinning) The earth is good, I regularly touch all the connections after heavy welding to feel for heat ie: arcing. When I strip and clean the earth connections I use copper conductivity grease to ensure good contacts. The porosity changes from small bubbles within the weld that only becomes visible when the weld is sanded to complete destruction of the weld with huge explosive bubbles.@Nitesky I've seen this problem once and had a tiny weld globule burn a tiny hole in a line as well, although Ive blown out the line Ive yet to pressurize it in a bucket of water to check for this. Since I have more than 8 metres of gas line on this machine I'm reluctant to change it all for perhaps nothing... but will have to soon if I find nothing. @Boilermaker237 Wire problems I've seen...Ive had several reels of good quality wire through this machine since the trouble started and put a couple of half rolls taken from other machines that were working well just to test this theory...no joy@Pro-Fab I don't have access to an external flow meter but have used a proper flow meter in-line and three different gauges/flow meters. Ive not given up on the gas leak scenario yet, I just cant find one.Interestingly, I was recently welding many small welds (tacks) on a large truck tray, the welder was not moved, the remote was not moved but the welder went from perfect welds gradually to complete porosity over 10 minutes or so...I wonder if this rules out the moving lines theory?  (Nah!) Ive learned over many years with Mig machines to NEVER rule anything out. Personally I find Migs to be very finicky machines that need lots of care, maintenance and constant work.@ifabric8 I wont rule out your suggestions but it's something I'm usually careful about, I lay my lines out straight or with gentle curves, of course there may be existing damage to the lines internally. I may have to replace the gas line just to rule it out.To All, clearly you guys have a great deal of experience between you and you've all had similar problems...and fixed them. Thanks for your great suggestions and I will try all those I haven't tried yet. Your continued input is much appreciated..
Reply:Well: the problem finally came to hand and has been fixed... I needed a piece of cardboard for a template and scavenged an old liner box, as I shaped my piece I noticed the box said 400-500 amp 1.2/1.6 as the size of the liner. I stripped out the now retired machine and found the liner was 8mm diam. instead of the 5mm diam one it should have had for that handpiece.  I ordered a correct one and the welder works like new, I've unretired it and use it everyday. Turns out the larger liner was cutting off the gas flow when ever the handpiece lead is moved even a tiny bit. The boss ordered the leads and discussed the hassles with the boss of the company that supplied the two wrong leads...what does that tell you except to NEVER assume the bloke next to you is doing his job as well as you are doing yours.Many thanks to those of you who tried to help out with this problem
Reply:Its been a while, but thanks for the update.Might help someone in the future with a similar problem.
Reply:Originally Posted by kymboWell: the problem finally came to hand and has been fixed... I needed a piece of cardboard for a template and scavenged an old liner box, as I shaped my piece I noticed the box said 400-500 amp 1.2/1.6 as the size of the liner. I stripped out the now retired machine and found the liner was 8mm diam. instead of the 5mm diam one it should have had for that handpiece.  I ordered a correct one and the welder works like new, I've unretired it and use it everyday. Turns out the larger liner was cutting off the gas flow when ever the handpiece lead is moved even a tiny bit. The boss ordered the leads and discussed the hassles with the boss of the company that supplied the two wrong leads...what does that tell you except to NEVER assume the bloke next to you is doing his job as well as you are doing yours.Many thanks to those of you who tried to help out with this problem
Reply:This thread shows why I use the hand-held flow meter at the tip of the gun on migs and tigs.  Unless you check the actual flow coming out the tip you never really know. (open the wire feed wheels so wire doesn't come out during the test) Attached Images Attached ImagesFlow tester Oxweld.pdf (8.2 KB, 25 views)