El laminated windshield introduced in the industry by Henry Ford turns one hundred. Its use changed the course of automobile history since it has become, together with the seat belt, the safety element that has saved the most lives and prevented injuries.
Throughout these hundred years, windshields have evolved a lot, but the basic concept of laminated glass remains unchanged and continues to fulfill its protective function, both from the point of view of road safety and health.
HENRY FORD AND THE "GLASS NECKLACE"
The first cars did not have windshields and their drivers had to wear glasses to protect themselves from the wind, dust and stones that could jump off the roads.. At the beginning of the XNUMXth century, the first windshields began to be introduced, consisting of two horizontal sliding glass panes: when the upper half got dirty, the driver could fold it up and move on. Oldsmobile was the first brand to include the windshield as a standard feature on all of its vehicles in 1915.
The advantages that this element brought soon turned into terrible disadvantages. With more cars in circulation, accidents also increased, in which the windows were broken into a thousand pieces. The driver used to be injured by the fragments of glass that were thrown, suffer serious injuries after going through the windshield head-on - generalizing the expression "a necklace of glass" - and by being thrown from the vehicle in an accident.
This reality, the fear of getting into a car and the rain of lawsuits against car manufacturers, led to work on a solution to this problem. Ford had already offered the windshield as an option in the Ford T and Henry Ford soon became convinced that safer automobile glass must be made; either because several friends had suffered accidents or because of the demands that he was beginning to receive.
AN INVENTION THAT WAS BORN BY CHANCE
Laminated glass had been invented in 1903 when the French inventor Edouard benedictus a glass fell to the ground and it did not break into a thousand pieces. The cause? That glass had contained cellulose nitrate and the dry film that remained on the glass held the pieces together when it was broken. In England, John C. Wood makes a similar discovery in parallel, but it is Benedictus who presented in 1909 the patent for two layers of glass with one of cellulose between them.
This invention began to have practical applications and laminated glass was widely used in gas masks during the World War I, but it took time to become popular in the automotive world due to its high price, complicated industrialization and because the intermediate layer faded over time and made the glass less translucent.
Aware of its existence, Henry Ford instructs him to Clarence avery, the mechanical "genius" of the company, who looks for a way to make a resistant and cheap laminated glass. Together with the specialist Pilkington a new, much stronger glass manufacturing process is created, which is produced at the same Ford River Rouge plant. At the end of 1919 they began to develop laminated automotive glass and in 1921 they began to be installed in models of the brand, as an option. The first standard laminated windshield was assembled by a Rickenbacker in 1926.
THE LAMINATED WINDSHIELD IS POPULARIZED
The advantages of the laminated windshield were obvious: it did not break into a thousand pieces, but in the form of a spider web; it prevented passengers from being thrown, and its strength added to the structural integrity of the car in the event of a rollover.
This great innovation only presented two major problems: its inner celluloid layer was discolored, darkened and became brittle over time, so it could be easily punctured. This was fixed in 1938, when Carleton ellis patented a transparent synthetic resin that did not fade over time. Beginning in the late XNUMXs, manufacturers began to use the polyvinyl butyral (PVB), which made laminated glass clearer and stronger.
Between the 30s and 50s, laminated glass was used on all the windows of the car, except for the rear. However, in the late 1950s, automakers looked for a cheaper option and began using tempered glass for the side and rear windows. Many safety specialists argue that tempered glass should not be used in the side windows, as they do not prevent passengers, or parts of their body, from leaving the cabin in the event of a side collision or rollover.
In the 60s the public became more interested in car safety and technology allowed the development of stronger laminated windshields. At that time, the National Highway Safety Administration (NHTSA), which began to establish federal standards for the strength and clarity of laminated windshields (FMVSS 205), the retention strength of the windshield during accidents (FMVSS 212), the stiffness of the roof in rollover accidents (FMVSS 216 ), and windshield penetration limits (FMVSS 219). Also in those years its use became mandatory in Europe.
OTHER ADVANTAGES OF THE LAMINATED WINDSHIELD
Laminated windshield improves acoustic comfort of a car for its insulating function. This translates into a more comfortable and safer driving by improving concentration behind the wheel. Some modern windshields have a laminate that can reduce noise levels by up to 30% by reducing aerodynamic hum as well as noise from rain.
Much more important, the windshield foil blocks more than 90% of UV rays, which protects the eyes and skin of the occupants of the front seats. Exposure to UV rays is cumulative and is associated with 90% of all skin cancers. Some windshields also offer thermal protection by incorporating a transparent sheet of metal oxides, which reflects infrared radiation and transfers less heat to the passenger compartment. This results in less use of air conditioning and, therefore, in a reduction in polluting emissions.