Kind of confused....

[Zephik]

Why do they make windshields and windows out of glass? Windshields mainly because of rocks that have been flung at them causing them to crack and break. Why do they not use a different material? Like acrylic or polycarbonate? Arent they, not only clearer than glass, but stronger as well? And even if you wanted to fork out the extra bucks, you could laminate polycarbonate and make it bullet resistant. So whats up with that??

-SF

[rosecityracr]

i know one things for sure, glass is a heck of a lot easier to clean and keep clean than any type of clear plastic i've ever messed with...i dont know for sure though. my dad's in the auto industry and ive asked him that before and gave me a logical answer but apparently i wasnt paying close enough attention

[GT40_GearHead]

the main reason i can think of is sun light and temp variation, two things that lexan, acrylic and polycarbonate hate, leave a piece of acrylic in the sun for a few days and you will see what i mean

[tybrenis]

For one, acrylic scratches very very easily, even more so with polycarbonate. Glass is also a lot cheaper to produce in that thickness and size, acrylic that size would have to be cast, and they is expensive and hard.

Also, acrylic isn't so great in weathering, it yellows. They do have "outdoor" acrylic now that resists that, but it's very expensive.

Also, acrylic and polycarbonate hold a lot of static electricity and always attract dust and other particles. Acrylic can only be cleaned with special cleaners or just water, for instance something like acid rain or even windshield wiper fluid might weaken it or make it blurry.

[Zephik]

lol well that explains it.

They need to make chip resistant glass then. Cuz flying rocks are too common!

-SF

[nil8]

Windshields are layered. There is are 2 pieces of shatter-resistant glass sandwiched around a thick piece of some plastic to keep thrown rocks from entering the cab of your car. If the glass didn't chip then it would either stick or go through the windshield. Chipping prevents both. It's rather ingenious really.

[CanaBalistic]

Laminated windshields are designed for safety, they are moderatly hard from the outside but are designed to let object's (human heads for example) through quite easily from the inside. Another thing is that acrylic tends to shater, flinging rather jaged pieces at high speed through the air. It's also more prone to scratches and hazing.

[Slug Toy]

ya, have you ever tried snapping a piece of plexi? its hard to do, but when it goes... wow does it go. little bits flying off like high speed razor blades... no kidding. its just asking for trouble.

[nil8]

Very similar to old glass I'm sure.
Windshields are a wonder of science and I'm sure in the next 50 years we will figure out a way to make them do their job better.

[Ironcat]

I have a friend who used to be an engineer for Ford and he is now an honest to goodness rocket scientist... so I asked him.
There are mainly 2 reasons and you guys have sorta hit on them already.

1: Plastic (acrylic, lexan, plexi, whatever you want) scratches very easily. A lot of mass commuter systems use plastic coated glass windows, if any of you take mass transit, check out the side windows of your local buses and trains... you will see a bajillion little teensy eeensy scratches, and this is from dust and wind and whatnot flying past the window and barely grazing it. Now imagine the scratches and therefore nonivis of front impacts with rust, sand, debris, etc.
2: Glass is ablative protection. This means that is you damage it a very small amount, a very small amount of it will be damaged (ie, chips). Glass will hold, chip, chip, chip, chip, crack, crack more, crack more, etc, giving you time to get it replaced... Plastic will hold, crack, and then shatter.