Quote:
Originally Posted by Big time
Being double curvature they can't (usually) be made by folding a flat glass.
Watching the cars from their sides you can see windshields and backlights are flat.
So are there any double curvature glass?
If so, how do they make the glass?
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I'm not aware of any production car today that actually uses flat or single curvature glass... maybe some industrial, agricultural vehicle applications, sure, but not production cars.
Tempered glass is made by heating the flat shape to soften it, lifting it onto a shaped mold (smaller lites by the edges, larger ones using forced air then pressing into a "hot ring" perimeter mold), then dropping into a perimeter support mold or "cold ring". Supported by its perimeter only, it is moved into the quench where high pressure air is blown over the hot glass to temper it.
Windshields are made by placing two sheets of thin glass together on a perimeter mold and heating the glass, allowing it to sag into the mold.
I worked as a Production Engineer at PPG's Oshawa Ontario glass plant before it was shut down. We made tempered back and side lites. I also spent some time in the Hawkesbury Ontario plant checking out their windshield process, quite different from tempered products.
Making glass with a single curvature (zero compound curvature) would require a completely different process, one that supported teh full shape of the glass somehow during quenching to keep gravity from adding any compound curve.
True, many windshields and back lites are very flat
looking on modern cars, but are anything but in reality.