Windshield Manufacturing Technology
The role that the windshield has played in the automobile has evolved over the years. With the advent of newer technology in the manufacturing process,
windscreen glass has changed from being just a transparent panel that keeps the wind off the driver's face, to a safety device that contributes significantly
to keeping the occupants of the vehicle safe. Today, most vehicles use heat strengthened laminated glass in windscreens- this comprises two pieces of heat
strengthened glass which are laminated together with PVB between them.
The manufacturing process is fairly complex, and needs to be carefully controlled to create superior glass that passes the highest quality standards. Glass
for windshields is manufactured using a float glass process, where the raw material (mainly silica and sodium oxides) is heated till it melts, and is fed
into a bath of molten tin on top of which it floats. While moving into the next chamber- a furnace- it hardens because of a drop in the temperature.
In the furnace, coatings are applied and then the glass is cooled gradually to room temperature. It is now very hard and ready to be cut. This cutting is
done using a diamond cutter; a process which is automated and controlled using optoelectronic measuring systems that ensure that the dimensions are perfect.
The cut glass is then bent into shape, using a mould which is heated till the glass takes the desired shape.
This glass is then tempered through a process of flash heating and cooling with jets of cold air. Tempered glass is very tough and breaks into small pieces
without sharp edges.
Once tempering and cleaning is done, the glass is laminated in an autoclave. This requires two sheets of glass to be bonded together with a layer of plastic
between them. Laminated glass stays together when broken, as the glass pieces stick to the transparent internal plastic layer. A laminated windscreen is very
thin- measuring approximately 4 millimeters after finishing.
After lamination, the windshield is readied for assembly. Plastic mouldings are fitted around the glass by injecting the plastic into a mould cavity which
contains the glass in a fixed position. The finished windscreen assembly is then shipped to the car manufacturer, who completes the installation into the
vehicle frame using a polyurethane adhesive that bonds the windshield and the vehicle body.
Stringent quality checks are carried out at every stage of the manufacturing process, to ensure that specifications related to chemical durability, impact
resistance and strength are met. Inspection for defects happens automatically during each process, and imperfect glass is rejected.
Even though the glass design incorporates the latest technology and the manufacturing process is state-of-the-art, the auto glass technician is the person
who is ultimately responsible for the correct installation of the windshield on your vehicle. Ensure that your technician has sufficient experience in
correct installation procedures, and does not use any short cuts while fixing your windscreen. Only then can you be truly sure that your vehicle and its
occupants are all protected from injury and stay safe - to the maximum extent possible - even during an accident!