Originally Posted by Skaggydog
I was under the impression from adds that the frame and body were galvanized (zinc coated) like my real Ram van.
When I told my wife I wanted to buy a Fiat, she said, "NOO Fix It Again Tony's"
Then when I told her it was "Made in Mexico" she said, "Are you kidding or are you crazy?"
Man, I do NOT want to hear "I TOLD YOU SO!"
It is galvanized!
Normal process these days is like this ...
Galvanizing comes on the raw material - it's on the coil going into the stamping presses already. Usually not all of the parts are galvanized, or it may only be on one side. (depends on the application of each part)
Welding destroys the galvanized coating at every weld, though, so you can't rely solely on the galvanizing. Some parts have sealer applied before welding - the heat from subsequent operations cures the sealer. The sealer seals the area between the two metal parts surrounding the spot-weld.
Outer door skins are usually attached by adhesive and hemming. A strip of adhesive goes around the outer edge of the door skin, then the door skin is placed against the inner structure and the edge of the outer skin gets folded around the outer edge of the inner structure - this is called "hemming". Look at the inside of your door edges ... you can see where this has been done. This is to avoid exposed visible spot welds. Hoods, tailgates, etc are the same way.
So, after the body is all welded, bolted (door hinges, fenders), or otherwise stuck together, the next step is e-coat, which is itself a multi-step process, to first clean and degrease and then apply the electrostatic coating. This coats every metallic surface inside and out and gets into all the crevices.
After drying, the next step after that is primer, then colour coat, then clear coat (if it is not a single-stage paint). All of these are applied robotically using electrostatic spray guns. The electric charge gets it into more nooks and crannies than you could normally get to by just straight spray painting and it greatly reduces overspray and gives a more even paint layer.
Galvanizing has traditionally caused trouble for paint adhesion ... but with this process, the paint doesn't have to stick to the galvanizing. The e-coat has to stick to the galvanizing, the primer has to stick to the e-coat, and the colour coat has to stick to the primer.