Most car owners would just look at the glass and not care about where or how it was made. All they have in mind is how it can protect them from the wind and road debris that comes flying at their face when they drive their car at high speeds. However, when it comes to replacing them, that would be the time when you have to send it to an auto glass repair shop.
The reason why the auto glass rarely gets the attention is that they were never emphasized in auto shows, to begin with. But one thing automakers have in mind when they think about auto glass is about the safety of its driver and the occupants. At first glance, it looks like the auto glass is the same as any other type of glass, but its functions are different.
In various homes, windows that are made out of glass are the type that shatter into large shards when it gets broken, except for the front door or the sliding door. The home windows usually do not receive the same kind of strain that the auto glass has. The car’s glass is made in 2 various types of safety glass wherein its aim is to protect not only the occupants within the vehicle but also its structure. One type is the laminated glass, which is used as the windshield. The another type is tempered glass, wherein its used for the back and side windows of the vehicle. Tempered glass also shatters into tiny bits of pieces when it breaks, thus lessening the chance it can injure the occupants inside.
PVB and Laminated Glass
Laminated glass is created by sandwiching PVB or polyvinyl butyral in between 2 pieces of glass. The PVB and the glass are then sealed through a series of pressured rollers, then afterward heated. With this pressure combination and chemical heat, it bonds the glass and the PVB mechanically. The mechanical bond happens via the PVB’s adhesiveness, while the chemical bond is done via the hydrogen bonding of the glass and the PVB.
The PVB layer that is inserted in between the glass allows the material to absorb the energy when it receives an impact. It also provides resistance to the glass when it gets hit by flying projectiles, especially when they are sharp enough to penetrate through. It can deflect up to 95 percent of UV rays emitted by the sun. Laminated glass can get punctured and break, but doesn’t break easily since it can stay intact due to the chemical bond its got with the PVB.
The laminated auto glass’ strength has a two important functions. Its first function allows the air bag at the passenger’s side to deploy the right way. The airbags at the driver’s side usually fly directly to the driver’s face from its steering wheel. However, when the air bag at the passenger’s seat is deployed, it gets bounced off to the windshield before it goes to the passenger.
It may seem like it would easily break the glass, but these auto glasses are made in a way that can handle high pressure. Did you know that the deployment speed of the air bag takes 1/30th of a second and can even withstand of up to 2000 pounds worth of force? The car’s windshield, by standards, can absorb the air bag’s force and speed for the simple matter of protecting the passenger from getting into an accident. And because of its power and strength, the laminated glass can protect the occupants when an accident happens. This was not the case in the past, since the passengers could only be ejected via its windshield since the auto glass during those times wasn’t strong enough.