Windscreens. Not the most technical part of a car, or the most expensive. But a necessary one.
We take a look at the importance of windscreens and delve into their past, present and future.
Firstly, windscreen or windshield?
- Windscreen = British and Australian
- Windshield = North American
We’re in Australia, so we’ll be using ‘windscreen’.
Driving without a windscreen would result in a bad day
Insects, dust, debris, rain, leaves all hitting you in the eyes, nose and mouth at 60 (or more) km/h. Windscreens play an important role in allowing drivers and passengers to see and breathe at speed on the road.
‘Strong winds’ at the beach mean around 40 km/h. If you’ve ever felt wind whip sand into exposed legs, you’ll know it wouldn’t be much fun in your face at 60 km/h.
Keeping a windscreen clean and uncracked is an important part of car interior protection.
They weren’t always as safe as they are today
Early windscreens were made from ordinary window glass which, when cracked, would result in sharp shards of glass hurled into occupants’ faces.
By the early 1920s, windscreens were made from hardened glass which shattered into smaller, more harmless pieces. Eventually, the use of laminated, hardened glass fixed in place with rubber seals was used to improve strength and durability.
Windscreens of today are much safer
Modern windscreens are glued in place. To protect the glue and sealants from UV damage, the edges of windscreens are darkened or coated with sun protectant.
Today, most windscreens are made from two pieces of glass with a plastic ‘interlayer’ sandwiched between them. The plastic layer is often tinted to act as an ultraviolet filter. The plastic layer, made from polyvinyl butyrate (PVB), is only around 0.76mm thick but this is what makes windscreens shatter-proof.
Vehicle safety authority, ANCAP, tests car windows to make sure they meet Australian standards.
Despite having three layers, windscreens are typically only around 5mm thick.
What happens to old windscreens?
Windscreens can easily be recycled. Many countries have environmental standards which don’t allow windscreens to be used in landfill.
To recycle a windscreen, heat is used to melt out the middle layer of plastic (PVB) which can be reshaped to new products. The glass layers follow a similar process.
Many modern cars have demister heating wires in the rear and front windscreens. Common and visible in the rear, front windscreens are more complicated.
Some use a grid of micro-thin wires to conduct heat to demist windows and melt ice. Although visible on close inspection, they don’t obstruct a driver’s vision.
Heads-Up Display. A HUD reflects data (speed, navigation information, etc) onto a car’s windscreen allowing driver’s to avoid looking down the gauge cluster or keeping their heads up and eyes on the road.
The area of the windscreen reflecting the information is treated with a transparent, reflective coating.
HUDs can also display visual warnings in the event of other vehicles or pedestrians approaching from the left or right.
Some automakers are developing windscreens that don’t require wipers to clean them. The benefit here is less wind noise when travelling at high speeds.
Ideas include pressurised air and water jets capable of removing dust and debris and ‘blowing’ away raindrops. Nano hydrophobic coatings and ceramic coatings can also resist water and dust.
Innovative EV company Tesla is reportedly working on an electromagnetic wiper system with a guide rail capable of wiping nearly 100% of the windscreen.
The future of windscreens
Some car manufacturers like McLaren have been experimenting with ultrasonic sound to repel rain and debris. Sound waves, produced by a transducer mounted in the corner of the window, ‘shake’ the glass free of rain, snow, mud, etc.
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