Written by Anthony Volk on October 17, Posted in Auto Glass Safety Tips. The modern windshield on automobiles is a product of several improvements over the original plate glass that was first used to protect drivers and make driving more comfortable. Unlike a standard glass window, the windshield on a car or truck will crack into thousands of tiny pieces upon impact — most of them held in place by a plastic film.
The first cars produced did not have windshields. But the first auto drivers soon saw the need for some protection. Even traveling at slow speeds, having wind blowing in your face, filled with bugs, rocks and other debris, made driving harder than it needed to be.
So, the first windshields were added to automobiles, made from the same type of glass used in household windows. With an increasing number of people purchasing and driving cars, there was an increase in accidents. It was soon discovered that the plate glass used in auto windshields posed a real danger to driver and passenger alike.
When the glass shattered and hit the people in the car, it was likely to cut them. And if someone was unfortunate enough to fly through the windshield — which happened with some regularity, as there were no seat belts— then he or she could easily die from lacerations. While there were efforts made to create a better windshield, such as the beginning of glass manufacturing at Ford production plants, it was an accidental discovery by a French chemist, Edouard Benedictus, that lead to the windshields used today.
Confusion in the lab caused a glass beaker to be put up without being cleaned. The glass still needs to be repaired or replaced from time to time, but this innovation provides much safer and durable glass for our vehicles. In the first step, the ingredients and water are mixed together in a refractory tank where they are subjected to very high temperature and melted. This chamber has a thin layer of molten tin upon which the admixture floats, hence the name of the process and the chamber.
From this chamber, the long sheet of molten glass is transported on rollers into another chamber, the lehr, which is a special furnace where the glass is annealed — gradually cooled. Next, it is shaped during and tempered though this is hardly the last step. The glass sheet is placed on or into a mould with the desired curvature and shape and then is heated just to the point where it becomes soft but does not melt and, as a result, sags on or into the mould.
Then it is cooled extremely quickly by shooting jets of cold air on it. This tempering process greatly strengthens and hardens the glass. The last step to make a windshield occurs when two sheets of tempered glass are put on each side of a very thin layer of Poly-Vinyl Butyral PVB. This sandwich is heated in an autoclave and pressed between rollers. PVB lends anti-shatter protection as, in case of collision, the PVB layer holds back glass shards from travelling at high velocities.
Different sensors, attachments and mouldings may be integrated or fabricated into the glass. These include everything from rain sensors to multi-use antennas to hydrophobic coatings. The windshield is now ready to be fitted and bonded into the metal frame of the vehicle.
The size of the windshield will ultimately depend upon the design of the vehicle. The inner poly-vinyl butyral layer is also cut to the same size. After all three pieces are separately cut and molded to the correct shape, they can be assembled to form one cohesive unit of layered glass.
This process is completed in an autoclave, a special oven that uses heat and pressure to bond the layers together. The windshield emerges ready to install in the correct size and shape as designated by the car manufacturer.
For this reason, it is next to impossible to replace a windshield with one from another vehicle that is considered inoperable. You probably have cracks in your windshield that resemble a spider web. For your safety, windshields are manufactured with safety glass made specifically for cars. What about the other auto glass on my vehicle? Call us at to schedule your appointment today. Author Recent Posts.
Taylor Auto Glass. Since , Taylor Auto Glass, a family owned and operated company has been the leading provider for auto glass repair and replacement in the Triad area. Latest posts by Taylor Auto Glass see all. Driving with a Cracked Windshield is Dangerous! Posted in: Windshield Repair , Windshield Replacement.
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