How Is Auto Glass Made?

Glazier worker cutting glass with compass glass cutter in a workshop. Industry

How is auto glass made? We know auto glass is a very important feature of a vehicle. It blocks wind and debris from entering the vehicle. The aerodynamic design of windshields help the automobile most faster and easier. Glass is used in various places in an automobile, as well, such as windshields, side and rear windows. We want to know more about how auto glass is made, so we investigated it. 

What Is Glass?

Glass is a material that has been in markets for thousands of years, both in its natural state and created. Glassmaking dates back at least 6,000 years. Throughout the 20th century, new ways of manufacturing glass led to widespread availability of glass. Therefore, the demand for glass went up.

Glass is made of oxides that fuse and react together when heated. Glass contains four main ingredients: sand or silica, sodium carbonate, lime or calcium oxide, and cullet. Let’s break that down a little further:

Sand or Silica – Silicon dioxide is a chemical compound known as silica. It is a type of sand that mostly consists of tiny granules of quartz. Silica has a melting point of over 2,000 degrees Celsius. It makes up about 60 to 70 percent of the entire windshield.

Sodium Carbonate – Sodium Carbonate lowers the melting point of silica to about 1,000 degrees Celsius. This makes the glass making process to be more efficient. However, it makes the glass water soluble.

Lime or Calcium Oxide – Lime or calcium oxide counter the effects of Sodium Carbonate. This makes the glass insoluble in water. Lime also improves the hardness and durability of the glass. 

Cullet – This is broken or waste glass that is added to facilitate melting in the making new glass.

Add water, mix these ingredients together while heating them at a high temperature, and you’ve got glass!

Making Auto Glass

Making auto glass does go a little bit deeper though. After the above materials are measured in appropriate amounts, the batch is melted using the “float method” glass process. This “float method” process got its name because the glass actually floats inside a chamber during part of the manufacturing process. In the opening of the float chamber, the temperature is approximately 1,000 degrees Celsius. This cleans the glass of any impurities. At the exit of the float chamber, the temperature is cooler, typically around 600 degrees Celsius, to allow the glass to harden. 

After exiting the chamber, any special coatings may be applied. The glass then enters a special furnace called a “lehr.” Here, glass is gradually cooled to about 200 degrees Celsius before cooling to room temperature to be cut.

Of course, the type of glass used for all windows in a vehicle is made of safety materials, set to standards by the OEM (original equipment manufacturer.) Windshields go through an additional process of lamination to provide extra protection.

Cutting and Tempering of Auto Glass

After the glass is cool, the glass needs to be cut to size and shaped. Using a tool called a “scribe,” a cut line is made into the glass, which is then broken or snapped. This step is most often automated for optimal accuracy.

The sheet of glass is then placed into a mold where it is bent into shape. The glass filled mold is heated in a furnace until the glass fills the shape of the mold. It is then cooled and removed from the mold.

Tempered or Laminated?

The glass is then tempered or laminated, depending on its final location in the automobile, to improve its strength. Side and rear windows are often made from tempered glass. The tempering process is done by quickly heating the glass, then blasting it with cold air. This process toughens the glass by putting the outer surface into compression and the inner into tension. This way, when the glass is damaged, the windshield breaks into many small pieces without sharp edges, making it safer for vehicle usage.

Windshields are laminated, so they are more likely to be completely shatter proof. The laminating process is important, as well. It gives the glass strength, provides safety and ensures good visibility. This process is when two sheets of glass are bonded together with a layer of plastic between them. There are different types of plastic used for different purposes. Some can block UV rays, while others are best for bulletproof glass. The laminating process typically takes place in an autoclave. Here, pressure and heat are used to form a single unit that is resistant to tearing. 

It is during this process that any sensors, attachments and moldings may be fabricated or integrated into the glass. 

Assembly of Auto Glass

Finally, the windshield making process is complete and assembly time is near. This process is usually done at a glass manufacturer. Here, the glass is set into a mold cavity. Next, molten plastic is injected into the mold. After this cools, a plastic frame is formed around the glass so the windshield can be safely shipped to a car or glass manufacturer. 

Future Of Auto Glass Manufacturing

Because of its strength and solid safety record, some car manufacturers are considering the implementation of laminated glass into all areas of their cars. BMW has placed laminated glass in the side windows of some of their models as an added protection against theft. 

However, laminated glass can take 10 times longer to break than tempered glass. This makes it difficult for a weakened or injured passenger to escape the vehicle in times of danger. This hasn’t stopped auto makers from designing new ways to get more laminated glass into our vehicles, though. Some manufacturers have even implemented a windshield that blends into the roof of a car, creating a full sky view within the windshield. 

We expect to see many changes in the future of auto glass, and we are so excited to grow with it. Remember, if you are in need of a windshield replacement or repair, contact us at Auto Glass Doc today. 

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    Got windshield cracks? Unsure of insurance coverage? Get free answers today!

      Enter your full name

      What is your glass issue?

      Enter a valid email

      Where can we reach you?

      Any additional information we should know about.