Positioner job

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I had these dropped off monday afternoon.  Just an easy job, piece work, weld and test each one.   Pipe is about 4", flange is 1".  I wanted to try some metal core NOT in pulsed spray mode to see how it works.  I started low and kept turning the wire speed and volts up until I got to 500 ipm and 29 volts 300 amps. This was about max because I could cut into the pipe pretty good when I started the weld.    I started out using a 300 amp lincoln gun, but it was smoking, so I went to my "Bernard style" 400 amp gun.  That problem resolved.  I couldn't use a .045 contact tip because the wire kept binding when it got hot, so I switched to the next size bigger contact tip.  I used the same tip for the rest of the job.I ran a few beads on flat plate to get the positioner speed close to what I needed.  Once the speed was set, I  didn't have to change it.  This positioner is either on or off.  No foot pedal, so I just left it running for the whole job.When I asked the customer when he wanted them back, he said the usual "Yesterday".  There are 43 pieces of each part.  Wire was Esab MC-6 gas 25 cfh 92% argon, 8% Co2  Positioner speed close to 3 rpm.  That is 20 seconds per weld.Here are the parts.  Customer had the flanges laser cut. They did a nice job.  Fit on the tube was perfect.  A machine shop cut the pipe and put a bevel on the other end so they could be welded to what ever.The tool.   I have no chuck, so welded tabs onto the tool and used T slot hold downs.  The setup.  See my fune extractor hood?    I hang the mig gun whip on an old wire spool to take some of the weight off it you can see the whip top left.  I put everything in reach so I can cook right along.  Last edited by David R; 03-16-2009 at 09:04 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:The piece properly spacedFlange with nice space to weld in.WeldWhen done with the first side, flip over and add 4 short welds between the holes with the table still turning.  I had to skip a weld because I wasn't quick enough to finish one and go on to the next one, so I let one space go by and caught it next time around.Pieces were cleaned up with a wire wheel, set in a jig and pressure tested at 150 PSI.  I had a few leaks from porosity right in the center of the bead.  I think it was from gun manipulation.  The leaks were just before the start stop at the end of the weld.  I am not sure why, but I think I had gone from pull to push. I fixed the leaks with tig, re tested, cleaned em all up and shipped them back to the customer the next day.  Customer liked the nice smooth bead inside.  No one will see them now, they are installed on some heat exchangers going to Korea.This was the first paying job for this positioner. It worked great.  My home made ground never even got warm.  My atlas 200 lb positioner is only rated for 200 amps.I get paid the same for testing as welding.  It took a lot longer to test them than weld them,but it was still a profitable job.Thanks for lookingDavid Last edited by David R; 03-16-2009 at 09:06 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Nice piece of work David.  After reading about your occasional leaks, I went back and looked over the photos.  The flanges are a pretty heavy piece of steel for welding with no pre-heat.  I see typical shrinkage pinholes in the craters of the intermittent welds you made on the outside of the part.  Rather than gun manipulation, I'm thinking you've got pinholes through the crater as a result of the rapid cooling at the end of the weld bead.  Preheating the flanges some might slow the cooling enough to prevent those pinholes from propagating all the way through the weldment.It's pretty much academic, because I'm thinking it's probably the same time to preheat the rings as it is to TIG repair the occasional leaker.Those intermittent welds on the outside of the flange sure seem odd.  They don't do anything to seal the joint, and it seems odd to go to the trouble in this instance.  Is that something your customer requests?On a different subject, I notices some white residue around those same exterior welds.  Are the parts galvanized?  Or is that some other kind of gunk burning off the parts?Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:A_DAB_will_do, You may be right.  I have not worked with this much heat.  If you look at pic # 3 post #2, I could burn into the flange pretty easy.  It was all mild steel.  I may have had too fast of a travel speed too. There was a line along the center of the weld.  Maybe from cooling too fast?  I dunno.  Maybe I needed MORE HEAT   Last time I did these, it was bare wire and pulsed spray.Yes, the intermittent welds were requested by the customer.  The first time I did these, they had me weld the outside only.  Then they found out there is no room for the bolts.........  So they wanted the inside welded.  The outside welds are "for strength".  I suppose there is a lot of vibration in a locomotive.The white stuff is probably because I didn't grind off the coating on the outside.  Its not really paint, Its not oil.  I tried welding one with out cleaning it off and it welded fine.  So I did em all that way.  I could see the penetration and if you look inside the pipe pics #3 and #4 post #2, I had enough heat there.Things looked a lot better after they were cleaned up with a wire wheel.  I took the photos like that to show how nice the metal core wire worked.  No slag and truly low fume.  I only needed the exhaust hood for the burning coating on the outside and what oil was on the parts.  I did clean off the flanges with solvent, they were oil soaked when I got them.   Pipe was clean (no oil) except the black coating on the outside.  I think pulsed spray metal core would have been the better way to go, but I wanted to use it "straight" for its high deposition.Thanks for the thoughts.David Last edited by David R; 03-16-2009 at 09:42 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:Here is a better pic.  If I had a leak it was on the left where the "slag" was in a line along the center of the bead.  The part was turning clockwise, so that is near the start stop.My goal is NO leaks.Here is a start stop.  It would leak where the "slag" or glass is heaviest.  There were not a lot of leaks, but....David Last edited by David R; 03-16-2009 at 09:50 PM.Real world weldin.  When I grow up I want to be a tig weldor.
Reply:It looks pretty good but I would say you went too fast with the positioner.Seems quite possible by the bead shape that there could be very small leaks at the edges or tie-ins. I would say slow the rpm down and feed it in with more backhand inclination.
Reply:That line along the center of the welds is something I've seen before with metal core wire.  Whether or not it appears is a function of cooling rate; but I don't think it's detrimental to the weld quality in any case.  More heat....More Heat....MORE HEAT....  (A welder's battle Cry)WAIT!  I'm on FIRE.  (What sometimes follows afterwards)Maybe slower cooling, instead. Originally Posted by David RA_DAB_will_do, You may be right.  I have not worked with this much heat.  If you look at pic # 3 post #2, I could burn into the flange pretty easy.  It was all mild steel.  I may have had too fast of a travel speed too. There was a line along the center of the weld.  Maybe from cooling too fast?  I dunno.  Maybe I needed MORE HEAT   Last time I did these, it was bare wire and pulsed spray.Yes, the intermittent welds were requested by the customer.  The first time I did these, they had me weld the outside only.  Then they found out there is no room for the bolts.........  So they wanted the inside welded.  The outside welds are "for strength".  I suppose there is a lot of vibration in a locomotive.The white stuff is probably because I didn't grind off the coating on the outside.  Its not really paint, Its not oil.  I tried welding one with out cleaning it off and it welded fine.  So I did em all that way.  I could see the penetration and if you look inside the pipe pics #3 and #4 post #2, I had enough heat there.Things looked a lot better after they were cleaned up with a wire wheel.  I took the photos like that to show how nice the metal core wire worked.  No slag and truly low fume.  I only needed the exhaust hood for the burning coating on the outside and what oil was on the parts.  I did clean off the flanges with solvent, they were oil soaked when I got them.   Pipe was clean (no oil) except the black coating on the outside.  I think pulsed spray metal core would have been the better way to go, but I wanted to use it "straight" for its high deposition.Thanks for the thoughts.David
Reply:At a past shop I worked in, anything over 5/8" thick was required to be pre-heated, even with metalcore.
Reply:Great work.Question, is that a trash can lid mounted on your fume extractor?  Neat idea.
Reply:I will try pre heat on a few next time.  I am also going to do it in pulsed spray.Thanks David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:When welding with metal core  you want that line down the middle of he weld
Reply:I took a Hobart filler metal class at the ITW warehouse this last spring and had a distinct line down the center of every bead I ran with metal core.  The instructor said that it happens when the settings and travel speed are pretty much spot on.  It's a solidification line.Why buy it for $10 when you can build it yourself for $100.