I'm purchasing a Mig welder in the near future, I've done a lot of Mig before, but I haven't owned a Mig welder. Personally I like gas welding.
The point is, I know that you have to remove the Galvanizing if you want to weld any sort of galvanized steel, But do you have to remove the plating if you want to weld Zinc plated steel? Is there any other coatings that have to be removed to weld the metals?
You are right about removing galvanized coatings.....sort of.. It depends on what you are welding and how critical the application. For example, I worked for a while welding big tables that held furniture stripper chemicals. They were made from galvanized sheet metal and we didnt clean anything before welding those tables.
We just welded em.
we welded the corners after the press brake bent up the pan. and we also welded a drain in the bottom. The only problems were that sometimes it outgassed and crapped up the mig tip occasionally .
Still much quicker than cleaning every joint. And we never had any returns.
Galvanized coating is pretty much made of zinc.
Since zinc melts at a much lower temperature than steel, it boils when welded and outgases.
Some other problems to watch for are using a high silicon content wire...if you are using bare wire mig welding. E70s2 would be a better choice than E70s6.
Too much silicon mixed with zinc can cause cracks.
Other than that, it is just plain better to clean the coating than to have to breathe the fumes from welding the coatings.
When you are welding galvanized, the Zinc fumes can make you sick and you might have funky dreams like you ate the tequila worm or something . I am serious.
I even read about one blacksmith guy who died from pneumonia after burning the galvanized coating off of a big hunk of pipe in his forge. It was a really sad story.
Other coatings that can cause problems are plasma spray, paint, and chrome.
All of these can make your welds brittle, and can make you sick if you breathe the fumes too much.