All of the parameters that you have listed are the ones that would have an effect on the penetration level. However, welding process (pulse/ CV), wire size, wire type (solid/ metal core), and gas mixture will all have a profound effect on the weld profile as well. We use many different solid and metal core wires, and all welding processes. The metal core really has a very fluid molten puddle, especially when the dia. gets .052 and larger. This very fluid puddle causes us to really have to move fast to keep the arc on the leading edge of the puddle to prevent inconsistent penetration levels as well as over lap or cold lap as some call it. The same factors can be said about running a really hot and fast weld around a small part. The amount of wire that is poured into the weld grows a very big bead, but the arc is just pushing into the already molten puddle and not into the base. Push angles and speed can both help to limit this. Another factor is the grounding of the part and the overall operating temp of the torch and work leads. As the temp of the cables goes up, so does the resistance, netting less power at the arc. Shoot me an email if you want to go deeper into it mdgwelding@yahoo.com
Good Luck!! Mark
Thanks For the reply (Mark?). Are you saying that I may have to increase my travel speed? Just to give you a little more backgroung on the process, we are welding a 5/8" rod to a 1/4" plate (both mild steel). the rod is fixtured horizontally, the plate is vertical (I believe you have seen this first hand). Er70S-6, .035 85/15 argon/co2. We've tried wfs of 360 to 440 ipm and tip-to-work distance of 1/4 to 3/4 in., with varying results, but still no consitancy. the total weld cycle is about 7.5 seconds. The equipment is Fronius. I've had a couple of the fronius techs look at the problem. They seem to get a nice looking weld but again no consistancy. I should add that we are also doing a simultanious weld at the opposite end of the rod to a .110 in. ring. So far, the penetration on the ring is fine. You also metioned the operating temp of the work leads. I have noticed the ground leads are warm (not hot) to the touch. Would increasing the size of the lead help? or reducing the length? we have approx 8' length of 2/0 cable, 1 cable to each ground. (each end of the fixture is grounded). let me know your thoughts. simons@gil-mar.com.
Mud,
I had a similar problem with an automated pulse spray 0.045 E70S-3 92Ar/8CO2 mig weld on an assembly like yours, 2-G rotated fillet weld between a vertical rod and a round base plate, except the "rod" had kind of a "J" prep on it, creating this pocket that was difficult to fill and fuse uniformly along with the base plate.
One problem was arc blow. Careful obsevation under the hood showed that the direction of the arc shifted during the weld. The arc blow was eliminated by moving the ground connection from the upper ram that pressed down on top of the rod, to below and around the base plate.
The other major factor was to keep a very tight arc length, to ensure that the arc was tightly focused and directed at the joint root. This weld ran best at the low end of voltage range, with a definite crackle sound to the arc, and some small increase in spatter as compared to a pure hissing, longer spray arc.
The best torch location was 45 deg. from horizontal, pointed right at the fillet root, 1/8" off of center on the "push" side.
We are also expieriencing Arc Blow, that seems to come and go. I have tried moving the ground which does affect the arc blow but has little effect on the penetration. We are using a 30 degree push angle, directed at the root, keeping a short arc. (1/8 in +/-).
as I stated in my orginal post, we have several similar weld cells, which all seem to run very consistant, though the components are different. This peticular one is a problem child.
Just a thought, did you say that you are running another weld at the other end of the rod simultaneously? If so this may have something to do with your arc blow condition. I have been around mechanized beam welding equipment and arc blow can be quite noticeable if the two arcs are directly across from one another when welding the web from both sides, by putting one arc ahead of the other, the arc blow ceased to be a problem. Are the two arcs that you are using at the same position of the clock on either end of the rod or is there any way to stagger their positions relative to one another? Good Luck! aevald
Yes, we are welding at both ends of the rod simultaniously, but only one gun per weld joint. The rod is 5/8 dia. about 6.5 in long. The two weld guns ARE at the same clock position. My plan is to double-check my grounding, then go from there. Thanks!
We originally started with .035 then switched to .045. but this didn't seem to change the penetration. just recently, we went back to .035. A Fronius engineer was out a couple of weeks ago and did some adjusting to the controls. the improvement was only slight. not much margin for error. Just this morning I adjusted the wfs up to 460 ipm, increased the travel speed slightly and moved the tip-to-work distance from .500 to .400. My penetration went from 13-18% to 20-30%! The weld looks "grainy" but if the fusion is there, I'm happy.
Thanks for your help. I'll keep you updated on my progress.
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