MCAW problems...help

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hey guys im an apprentice trying to get my cwb for metal-core. I have my hardwire GMAW cwb but have had continuous problems with my MCAW and lack of fusion, even with my 1GF. I'm runnin .045 wire with 85/15 argon/co2. Running my machine at 25.0 volts and 400 wire speed, everything feels good going in, everything looks visually great even my stops and restards but when it comes to the bend test I have lack of fusion in some areas and I cant understand why! My last bend test my cap was good and my fillet side stop/restart coupon was good. But I got a crack on the fillet side on my groove stop/restart coupon. Any pointers on what I could try? thanks guys
Reply:How's your Alu welding skills? From my experience if you can get a start stop to work good on your Alu cwb test your metal core is a lot easer
Reply:These are my first times ever using the MIG/MAG process. We never use it at work its always stick/tig for me but its a pre-requisite for me to have these tickets to finish my apprenticeship. Literally just picked up the gun for these processes last week. Im more or less wondering if theres other ways I can set my machine to achieve what I need. BTW I drag to try to maximize penetration but it still seems to be my #1 problem!
Reply:Could you provide some more details about the 1G test?
Reply:Are you prepping your own test plates? How is the backing strip being removed?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:I know an applications guy at Hobart that's given me some really good help with running metal core.  I'll email him the link to this thread and hopefully he'll step in.  You're going to have to provide some more information though.  Especially which wire you're running.
Reply:Livinthelife,4956 is right and we need some more information to help sort out the issue you're having.  A couple things do come to mind that I can ask in the blind though:1.  What is the joint geometry(bevel angles, root opening, backer (y/n?))2.  How many beads and layers are you using to weld the test plate?3.  What is the MC product name and manufacturer?4.  Are you cleaning any silica bead residue from the beads with a wire wheel between every pass?In my experience you can push or pull MCAW wires.  The classic technique is to use a good spray transfer and push the puddle.  But this isn't mandatory in my opinion.MCAW has a wider arc cone and shallower penetration than the same size solid wire.  Generally speaking The burn off rate(deposition rate) for MC wires is higher than solid wire, AT THE SAME AMPERAGE setting.  This means a larger molten puddle at a given travel speed than what you're accustomed to with solid wire.  If you are weaving when depositing the beads you can have lack of fusion because of the inherently shallower penetration that you get from metal cored wire.  I've attached pictures of two possible bead sequences for material about 3/4" thick.  Don't get to hung up on the joint geometry details.  Pay more attention to the bead sequences shown.  The first image shows wide, single bead fill passes an a late transition to a split bead cap.  This works fine with FCAW; but the wider beads in the middle of the fill COULD be problematic with a MCAW wire.  Broad sweeping weaves with big steps forward could allow weld metal to wash into the bevel with insufficient heat to achieve 100% fusion into the base metal.  Failing to remove glass deposits between passes could allow weld metal to wash over them and trap them as slag inclusions.  The second bead sequence, starting more, narrow stringers earlier in the weld sequence, is safer.  This keeps the heat of the arc closer to the bevel for a greater percentage of the time.  But you still need to clean any glass residue from the surface between each pass.  Guys will tell you that the glass floats to the surface of each successive bead.  And it will if you have enough heat to keep the glass and the puddle liquid for enough time.  But it's a gamble unless you know exactly what you're doing.  Much better to play it safe and run more, smaller beads and clean after depositing every single one.That's my best guess for advice without some more information.  Post some photos of your failed straps with closeups of the defects, if this advice doesn't help.  Also fill in the answers to the questions I and others have already posted.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:These are the root and face bend straps from some 3/8" open root test plates done with metal core.  Number 18 was done on a 45 degree angle (trying to simulate where you'd be welding on a 1G pipe), 19 was done vertical up and 20 horizontal.   The root passes were done in RMD mode and the fill and caps in ProPulsed mode using a Miller PipePro 450 RFC machine.
Reply:Originally Posted by LIVINtheLIFEhey guys im an apprentice trying to get my cwb for metal-core. I have my hardwire GMAW cwb but have had continuous problems with my MCAW and lack of fusion, even with my 1GF. I'm runnin .045 wire with 85/15 argon/co2. Running my machine at 25.0 volts and 400 wire speed, everything feels good going in, everything looks visually great even my stops and restards but when it comes to the bend test I have lack of fusion in some areas and I cant understand why! My last bend test my cap was good and my fillet side stop/restart coupon was good. But I got a crack on the fillet side on my groove stop/restart coupon. Any pointers on what I could try? thanks guys