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Different Types of Glass used in Car windscreens
When a car company runs an advertisement highlighting its vehicle’s safety features, they rarely focus on the car windshields or windscreens safety functions.
Car windscreen has a lot of roles and functions. Besides giving structural support to the roof and airbags, preventing occupants from being thrown out during an accident, it also gives protection against wind and flying debris, such as dust, insects, and rocks from entering the vehicle’s passenger chamber.
Types of Auto Safety Glass
There are two significant types of auto safety glass which include laminated and tempered glass.
Typically, laminated glass is used for front windscreens, while tempered glass is used for rear and side windows. Although each glass has different functions, they have a common purpose of keeping the occupant inside the vehicle in case of an accident. They protect the passengers from flying pieces of sharp glass and retain the roof’s rigidity in a rollover.
Let’s look at each type of glass, as well as its pros and cons.
Laminated Glass
The lamination process starts by simply stacking two pieces of glasses together with a plastic interlayer known as Poly-Vinyl Butyral (PVB). Extreme heat and pressure are then applied to the combination, which in turn fuses the PVB and sheets of glass together. Although laminated glass is breakable, it eliminates the shards from flying off in a collision. The glass is made to endure extreme impacts without shattering, therefore increasing the passenger’s safety by reducing potential injury due to flying glass. Another benefit is that it protects drivers who are not wearing a seat belt by acting as a barrier in case they are thrown forward onto the windscreen. This glass can be fixed in the case of minor damage such as small chips or cracks.
Tempered Glass
Also known as Toughen Glass. Generally, tempered glass is made through a technique known as tempering, making it harder and stronger than any other standard glass. In this process, a sheet of glass is heated up to a specific temperature and then cooled rapidly with cold air. The process forces the glass to expand and then contract suddenly, and as a result, the outer layer hardens while the inner layer is induced with tension. The procedure often renders it ten times stronger than regular glass. Should the tempered glass break, it shatters into thousands of non-sharp pebble-like pieces which cannot cause bodily harm if they were to fall onto a person’s body. Unfortunately, once broken, tempered glass cannot be repaired, and the only solution is to replace it. Tempered glass is mostly used for making rear and door windows in the automobile industry.
Replacement Glass Options
When the glass on your car breaks, there are two types of replacement glass available which includes OEM and Aftermarket auto glass.
OEM Auto Glass
The word OEM stands for Original Equipment Manufacturer. This means that the glass is usually fabricated by the same manufacturer that provided the original glass in your vehicle. In essence, the glass is identical to what the car had before developing the hitch. Usually, an OEM glass has a distinctive automaker branding.
Aftermarket Auto Glass
This type of glass is created by a company (other than the original manufacturer) to fit specific vehicles. The Aftermarket auto glass can either be the same quality as OEM or lesser quality.
THE USE OF ADHESIVES ON WINDSHIELD
One of the most common and dangerous mistakes that people make while replacing a windshield is using the wrong type of adhesive. There are several materials like bathtub caulking or silicone which should be avoided completely. The established International Standard specified the products to be used as bonding adhesives for windshields is only Polyurethane. It is important to utilize strong adhesives to hold safety glass in place.
But first, it is important to understand the difference between adhesives and sealants. Adhesives are used to bind two different bodies together and sealants have chemicals that form a flexible and waterproof filler that fill the gaps and prevent the entry of water. There are a few differences between Polyurethane (adhesive) and Silicone (sealant) which include:
Polyurethane is 90 times stronger than silicone. Unlike Polyurethane, silicone has better prolongation and it gets softened by high temperature & humidity.
The few advantages of Polyurethane are:-
In case of an accident or a collision, Polyurethane prevents the windshield from coming off from its frame, so it prevents the roof from caving in when the car rolls over. Windshield and its adhesives are exposed to extreme weather, i.e. ultraviolet ray, rain, cold, heat, humid and salt air for years to verify long-term strength and durability, car makers use Polyurethane to bond the windshield to the frame of the car. Adhesives are exposed to cold, heat, humidity, rain and salt air for years to verify long-term strength.
During the windshield replacement process, the right balance between the viscosity and thixotropy of the adhesives should be ensured. It should be made sure that these Polyurethane adhesives should not leave little trails over the windshield.
Professionals should be contacted for the use of accurate adhesives.