Another 'How do they make that' question. (Curved Laminated Glass)

This is one product that I really puzzled about.
For flat laminated glass panels I can see how two sheets can be bonded/fused
to the inner plastic layer, but how one earth is single and dual curvature laminated glass made.
Presumably the plastic interlayer would not stand the temperature needed to form the glass, so both glass sheets must be moulded to slightly different but incredible high tolerance so that there are no air pockets, which to me seems unlikely.
I have Googled this topic several times over a few months, enquired in person at the St Helens Glass Museum, and asked knowledgeable automotive industry people, and not yet come up with an answer.
I know this is off topic regarding ME (unless one counts driving to the local metal stockist in a car fitted with a curved laminated glass windscreen!)
Ian Phillips
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Here's a partial answer http://en.wikipedia.org/wiki/Laminated_glass
Henry

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Air bubbles wouldn't be a problem if it's assembled under vacuum, and if the interlayer is soft enough to flow to accommodate curvature mismatch.
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Don't know if your familar with the "How it's made" series on Discovery, but they showed the process of how they made car windscreens.....
Can't remember I'm afraid.
Michael
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Michael wrote:

I saw it too... a very interesting series if you like watching automated things!
As far as I can recall: Make float glass, cut into windscreen-like shape. These fit over a concave mould, and are heated until they sag into the right shape. In the tv show it was hard to see the mould - presumably very shiny - and almost looked as if the glass was sagging under it's own weight; but this must be the highly repeatable part. Then the formed glass is toughened.
To laminate, a glass-plastic-glass sandwich is rolled/pressed to remove air, then autoclaved. The plastic was poly-vinyl-whatsit and looked quite thin, like strong plastic bag thickness. Couldn't tell whether the two glass parts are from the same mould or not, unfortunately... I guess this depends on how tight the curvature gets. I noticed the crosshatch pattern in the laminate left by the rolling process is often visible in windscreens, especially at an angle.
btw, searching for 'how windshields are made' might give more detail.
hth Guy
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Ian wrote:

Perhaps they form the 2 sheets together with an initial spacing sheet which is of the same thickness as the later bonding material?
Tom
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Interesting question.
Some good clues here: http://mainland.cctt.org/istf2007/manufacturing.asp
Pat Mackenzi
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Pat
The mainland site is one I missed in my searches, it certainly explains the process well enough to satisfy my curiosity, thanks!
Ian
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