Re: [DML] Re: Frame Flex? (weight of galvanising)

[mike.griese@xxxxxxxxxxxxxxxx]

Manufacturers have been using single-sided galvanized sheet metal for 
quite some time for exterior panels.  Door skins, fenders, deck lids and
hoods have had this treatment since the early 80's.  It's not always 
completely successful because of the processing required to build 
the car - some zinc boils off when the assemblies are spot welded 
together, and some raw edges are left when panels are trimmed to 
fit.  Why not double sided?  mainly because it is difficult to get 
a good paint finish over a galvanized panel.  The paint doesn't 
want to adhere well.

Now manufacturers are moving towards plastics in non-structural
panels (like hoods, fender skirts, etc. as a way to save weight and
improve mileage.  Single-sided galvanized panels are still used 
for some structural items.  

--
Mike


-------------- Original message from "David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>: -------------- 


> Galvanizing (zinc coating) is an excellant way to preserve a mild 
> steel frame. The drawbacks include a weight penalty and possible 
> warpage. Even scratches are self-healing to an extent. The zinc 
> sacrifices itself to prevent the steel from oxidizing, just like the 
> zincs you would use on a boat. It is not commonly done on cars because 
> of the weight penalty and the expense. Instead the auto manufacturers 
> are moving over to composites and plastics. Look at the wheel well 
> housings on a modern car, they are plastic as are the fasteners. You 
> will see a composite frame in the near future just as JZD had 
> origionally plannned for the Delorean! Another drawback to zinc 
> coating is the danger of welding and grinding. You MUST protect 
> yourself against the fumes from welding and the zinc dust when 
> grinding. The dust and fumes are very toxic. 
> David Teitelbaum 
> vin 10757 

[Non-text portions of this message have been removed]





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