Dissimilar thickness welds
Dissimilar thickness welds
(OP)
Is there a rule-of-thumb for the maximum difference in material thickness for two members to be joined by GMAW? I am interested in general applications, but a specific geometry is as follows:
50 mm tube OD x 2.25 mm thickness
low carbon steel (HSLA or plain carbon)
3.5 mm bracket
low carbon steel (HSLA or plain carbon)
The bracket encircles the outside of the tube, creating a lap joint. The concern is that excessive heat will cause burn-through of the thinner tube. Let me know if I forgot anything.
50 mm tube OD x 2.25 mm thickness
low carbon steel (HSLA or plain carbon)
3.5 mm bracket
low carbon steel (HSLA or plain carbon)
The bracket encircles the outside of the tube, creating a lap joint. The concern is that excessive heat will cause burn-through of the thinner tube. Let me know if I forgot anything.





RE: Dissimilar thickness welds
Rod
RE: Dissimilar thickness welds
I agree with evelrod. With an experienced welder and the right equipment you can weld these materials and thicknesses with relative ease.
However, any tubing that used for gas or fluid service may be another story regarding burn-through.
What is the application?
RE: Dissimilar thickness welds
Gas and fluid service.
Actually, the parts are for an automotive strut. Parts must not leak (gas or oil) during service. We haven't had any problems with this design, but I couldn't remember the general rule. We may need to increase bracket thickness with tube thickness remaining the same, so I'm curious where it starts to become a problem.
RE: Dissimilar thickness welds
Is this a reservoir or the strut body?
Are there moving parts in your weldment such as pistons or valves which would require a uniform surface or precision finish?
Will the tube ID be machined after welding?
Will the parts be manually (semiautomatically) welded or by mechanized or robotic process control?
FYI: There will be some distortion of the tubing at the location of the weld on the opposite side of the joint (tube ID).
Not trying to confuse you, just making sure all the bases are covered and you (or this reply) have not overlooked any potential problems after welding.
RE: Dissimilar thickness welds
Thanks and regards
Sayee Prasad R
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RE: Dissimilar thickness welds
1. Strut body
2. No
3. No
4. Robot
Sayee,
GMAW will be used because this is the equipment that the production facility already has-- a common problem with high volume automotive manufacturing. I like your suggestion of autogenous GTAW welding, but there is no opportunity to use this method. Alas...
Thanks for the replies. If anyone comes across a design guide, handbook, etc. with a recommendation on thickness differential not to exceed, feel free to post it.
RE: Dissimilar thickness welds
The GMAW process complimented by robotics will work just fine for your application. You will not be limited by thickness either, to a point. Very thin materials (thinner than the ones you are joining) can be welded using a set-up such as yours. 0.030" dia. electrodes may weld relatively thin materials.
Robotic cells, once dialed in correctly, will perform satisfactorily for an application such as yours.
The best of luck (not that you'll need it!)
Another FYI;
Last year during an audit of a manufacturing facility, a client wanted to show off their robotic cell. (Tube to flange w/fillet weld appplication.) They used magnetic part-positioning methods. It was a disaster as far as demonstrations go, the arm just touched one of the parts resulting in a dominoe effect which moved several other parts out of position during the cycle. I got to watch all of the parts that were set-up get knocked all over the table by the arm, one of them was partially welded to the table. Not too impressive...
RE: Dissimilar thickness welds