American Welding Society Forum
I have a problem with welding of Nelson Anchor Bolts with diamensions 19mm diameter 125mm length (St37-3). I've adjusted the machine (TRW2800 ampere in capacity) to 1750A and 0.550sec, when I weld the trial pieces on a horizontal test plate I got a sound weld. However when I started to weld the stud on to a vertical work piece ( half cone ) the weld ring doesn't have a sound appearance the ring is not a complete circle it has a drop down view due to gravity. I have tried different parameters from 1550 to 1950 A and 0.550 to 0.95 sec and changed the earthing connections to different points (both at the bottom, both on top, one on top one at the bottom etc.). Unfortunately I couldn't achieve a sound weld. Would anyone of you have such an experience? Your urgent kind reply is apreciated.
Having a complete ring around the entire circumference on an out-of-position stud weld is not a good indicator of weld soundness. Weld on in the same position on scrap steel and do a quick cross section - if there is complete penetration under the stud, and no undercut (or a slight undercut if allowed by the code) then it is a sound weld.
The "ring" isn't there to provide strength, it is merely flashing.
Also, if this is a large diameter stud, be sure you have the horizontal type of ferrule - it has ridges only halfway around where the ferrule meets the BM. The other half is flat and that should be under the stud - th ridges above it.
I didn't realize there were different ferrules for verticals. No one around here ever shows us these things, they just tell us to get it done the best way we know how. I'm glad you mentioned this in your reply.
Have a great day,
Have you tested the studs that you did not see a 360 degree flash to make sure they indeed did not welded properly? Bend the stud in the opposite direction of the missing weld 15 degrees. This should verify if the stud is properly welded. This might sound silly, but are you holding the gun still and level until the weld metal has solidified? You mentioned a half cone, are you refering to the ferrules? We use the same flat ferrules as you would use in the flat position and achieve satisfactory results. What code or spec are you working to?
Actually I must be more clear that the work piece that I have to apply the studs is a cone that is called as draft tube cone, is used after the turbine of a Hydroelectric Power Plant is going to be mounted into concrete. Moreover as test we applied bend test to both sides in 30 degrees and also to one side 60 degrees, as per the bend test we don't have any penetration problem. However our customer has not been convinced with the bend test, so they request us to improve the welding method. this is the situation we are in now. As an answer to your question we hold the gun still untill the spark ends. Would you suggest that we should hold it for more seconds?
Thanks for your reply.
Our guys have trouble when they are not holding the gun level. Sometimes they think they are level, but someone standing to the side can verify that they are indeed level before squeezing the trigger.
I'm sorry, I can't be of more help,
It's very important that the gun is 90 degrees to the work piece and that may be difficult on the piece you are trying to shoot studs onto.
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