Posted by Sherman in Idaho [72.47.9.37] on Thursday, November 08, 2012 at 12:29:53 :
In Reply to: I think fillers are dipped= in solder! posted by Chris Case [75.36.46.254] on Thursday, November 08, 2012 at 08:56:58 :
You're probably right about being dipped in solder. Your static electricity theory isn't right, though. All metals conduct electricity totally perfectly for static discharge purposes. I suspect the reason for dipping them in solder is to seal all possible leaks, and because it's a simpler manufacturing process than having someone hand-solder all the seams. The question remains, though, about why dip them in solder rather than zinc. Buckets and watering cans get their seams sealed by dipping them in molten zinc. Both processes work well if the steel is well cleaned and the proper flux is used.
Spot welding or resistance welding would not work well for melting the zinc or the solder. Anything that gets red hot will burn and boil off any zinc or lead, which would then leave oxides that would make subsequent soldering difficult. The manufacturing process would be to fabricate the part with all needed welding, then pickle it, and then immerse it in molten zinc or molten solder covered with a layer of flux.
One possible reason to use solder rather than zinc is as you described, the higher temperature of the zinc. Another reason is more flexibility. 50/50 solder will accommodate a certain amount of stress and vibration without cracking, whereas sinc is hard and brittle.
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