Welding Tips and Tricks

Hi all! I have been looking at these welds...I think that the first one is resistance spot welding whereas the second one is GMAW welding...but I am not sure about it. Have I guessed it right based on the looks and the position of the weld?

If you are referring to the body panel seam its likely fancy glue.

the round dots is spot welding (resistance welding).
the weave line is glue. its common to have a mix of both, the panel will be glued and have a few spot welds to hold it in place. that also water proofs and sound proofs the join.

Yup.. First is chemical seam-sealer, second is spotweld.

It's very uncommon on any production car to find seam-welds on any body panels. They are all spot welded together at the factory as that's way faster in a factory setting to manufacture.

Strength in these usually comes from the way the sheet metal is folded/creased and for instance one section made into an 'U' shape, the other fitted into the groove and then the whole thing spot-welded as a 'sandwich' making the whole joint rigid.

Classic cars that pre-date good spot-welding equipment will often use some sort of solder or braze sections to fit panels together.

All to minimise distortion on the thin but big sheetmetal.

Only places you'll find seam welds usually is on separate components like suspension arms or pickup points and in case of a separate chassis you may find some parts welded on these too. Most of those will be (robotic) MIG though, again for speed and consistency of manufacture.

Only on track/race/rally cars will you find seam welded bodywork (if a allowed by regulations when competing) as it does stiffen up the bodyshell and the high (cyclic) loads on the body can start to tear/break the factory spotwelds and once enough break then the body 'box' kinda becomes a wet rag in a structural sense

But that's quite a labor-intensive and manual process (==expensive), so even on race cars you often see that only certain known weak connections between panels in the bodyshell are done this way and the rest left 'as is'. Also more outboard/exposed sheetmetal parts are a lot easier to pick loose and replace in case of damage if they are spot or plug welded on the factory points and not fully seam-welded.

Bye, Arno.