MIG penetration problems

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hitt cues 22 years ago

I recently purchased a used Miller Trailblazer with a few accessories, including a spool gun.

I was not a terrible stick welder many years ago and have heard so much about MIG that I decided to give it a try. I learned to stick weld by practicing beads on a piece of angle iron so I repeated the lesson with the new rig.

I set up a 4x4x.5 angle and struck my first arc with .035 flux core wire (E71T-GS) and began to practice adjusting the wire speed set at a constant 30v (3/4 throttle).

The results approximated those discussed on this group except with ZERO PENETRATION. I can easily knock the bead off with a cold chisel. I was running DCEP so I swapped polarity and tried again, thinking I had simply become confused. The results were immediately questionable so I rechecked the recommended polarity, went bwck to DCEP and tried again with the same results.

I then tried a copper coated .035 solid core wire (ER70S-6) with the

75%/25% argon/CO2 shield gas flowing at approximately 30 cfh set DCEN at a constant 30v and began to adjust the wire speed (amperage).

Once again, the results approximated the anticipated (from group discussion) and once again ZERO PENETRATION. I swapped polarity, increased the voltage and amperage, however I was still not able to even disturb the freshly ground surface of the angle iron. The pretty, albeit fat, beads are easily removed with a cold chisel.

Any suggestions? If so, thanks in advance.

I'm beginning to think my machine needs service but before I haul the thing to the shop, I though I might solicit observations from this learned group.

Thanks for tuning in. HA Bruce

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Ecnerwal 22 years ago

I've got all of about 5 minutes experience on a MIG, but that was prefaced by my instructor describing his neighbor welding up these huge beads to hold something onto his truck bumper, which then proceeded to fall off due to no penetration. It's a technique issue rather than your equipment, in all liklihood. Something about needing to drive the wire in/scratch it around rather than just letting it lay metal on top; a difference from regular stick technique. Hopefully somone who uses one more will have a better description, as I can't really remember exactly what it was we were supposed to do to prevent this problem, since I spent very little time on the MIG; I wanted to play with the TIG, and there was not enough time in that course for doing a lot of both.

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Zorro 22 years ago

Get this free from Lincoln. MIG/MAG Welding guide

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pages 26 through 29 for some example settings and gasses.

Most of the time you will use... Solid wire MIG/MAG - electrode positive Flux cored/Dual shield - electrode negative

I'm not familiar with the TrailBlazer but I wish I was! I would lower the voltage to the low 20's and adjust the wire speed to get a nice smooth sound... and when using gas... indoors 15 to 25cfh and outdoors in a

5mph wind or less 15 to 40 cfh. More than 5mph wind and you should put up a wind breaker around the gun area. Just running beads on top of metal should be easy. You won't take long to get it. Watch the puddle. It will be high (and cold ) on start but should begin to sink a bit according to travel speed. If it does not sink then you could slow down to let the metal heat up. A hot start setting would be nice. Keep the tip close in there with solid wire. More distance with flux but not too much. The Lincoln book will tell you somewhere around a quarter inch to half inch.

If you decide you want to sell that TrailBlazer, I've got $200 cold cash waiting to find a new home! ;^)

Zorro

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R. Duncan 22 years ago

E71T-GS .035" is a self shielding fuxcore wire for thin metal (body pannels, duckwork) with 110V welder DCEN is used.

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Welding parimeters

120 AMP 17 V 155 IPM Link is welding parimiter chart for that wire.

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Here is better link

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thicker version of that wire was used it could work on 1/2 inch steel.

Link for welding parimiters for your solid wire that shows your problem.

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This link is Hobart Brothers welding wires & stick electrodes Product Information

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Buy Miller MIG welding calculator for wire selection and settings. Miller web site has student package with lots of information cheap.

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Gary Coffman 22 years ago

Way too much voltage. Try about 17 volts. Also, make sure you're using backhand technique, ie the gun should point back toward the already welded area by about 15 degrees as you drag it along. If you use forehand technique (ie pushing) you'll get much less penetration. Watch the puddle to gauge travel speed. Penetration should be nearly as deep as the puddle is wide, and the puddle shape should be nearly round. If it starts getting wider than it is long, you're moving too slow, or if it is much longer than it is wide, you're moving too fast.

Once again, way too much voltage. Drop the voltage down to the

16-18 volt range and crank that wire speed up until it starts stubbing. Then back off on wire speed a tad until the arc sounds like frying bacon. *Now* you're cooking.

Gary

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R. Duncan 22 years ago

Only selfshielding flux core wire use elctrode negative. (InnerShield)

Dual shield, Outer Shield, gas shielded or whatever you want to call flux core wire that requires shielding gas all use electrode positive.

Don't take my word for this look at your wire's product information.

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Zorro 22 years ago

Thank you for the correction. I think it is good advice about looking at the wire's documentation. I remember a discussion here a while back about one of the flux wires using an uncommon polarity so I wasn't sure. Of course I did a "doh" on the dual-shield. It is DCEP. Once again, check the wire's documentation. There are flux wires out there that use uncommon polarities.

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MIG penetration problems

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