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The windshield (American English and Canadian English) or windscreen (Commonwealth English) of an aircraft, car, bus, motorbike, truck, train, boat or streetcar is the front window, which provides visibility while protecting occupants from the elements. Modern windshields are generally made of laminated safety glass, a type of treated glass, which consists of, typically, two curved sheets of glass with a plastic layer laminated between them for safety, and bonded into the window frame.
Motorcycle windshields are often made of high-impact polycarbonate or acrylic plastic.
Windshields protect the vehicle's occupants from wind and flying debris such as dust, insects, and rocks, and provide an aerodynamically formed window towards the front. UV coating may be applied to screen out harmful ultraviolet radiation. However, this is usually unnecessary since most auto windshields are made from laminated safety glass. The majority of UV-B is absorbed by the glass itself, and any remaining UV-B together with most of the UV-A is absorbed by the PVB bonding layer. [1]
On motorbikes their main function is to shield the rider from wind, though not as completely as in a car, whereas on sports and racing motorcycles the main function is reducing drag when the rider assumes the optimal aerodynamic configuration with their body in unison with the machine and does not shield the rider from wind when sitting upright.
Early windshields were made of ordinary window glass, but that could lead to serious injuries in the event of a crash. A series of crashes led up to the development of stronger windshields. The most notable example of this is the Pane vs. Ford case of 1917 that decided against Pane in that he was only injured through reckless driving.[ citation needed ] They were replaced with windshields made of toughened glass and were fitted in the frame using a rubber or neoprene seal. The hardened glass shattered into many mostly harmless fragments when the windshield broke. These windshields, however, could shatter from a simple stone chip. "Triplex" glass laminating, however, had been available for windshields in France from 1911 and in Britain from 1912; it was adopted as an accessory by some high-end American auto manufacturers beginning in 1913, and from 1919 to 1929 Henry Ford ordered the use of laminated glass on all of his vehicles. [2]
Modern, glued-in windshields contribute to the vehicle's rigidity, but the main force for innovation has historically been the need to prevent injury from sharp glass fragments. Almost all nations now require windshields to stay in one piece even if broken, except if pierced by a strong force.
The urethane sealant is protected from UV in sunlight by a band of dark dots called a frit around the edge of the windshield. [3] The darkened edge transitions to the clear windshield with smaller dots to minimize thermal stress in manufacturing. The same band of darkened dots is often expanded around the rearview mirror to act as a sunshade. [4]
On a rainy day, water refraction on aircraft windshields can mislead pilots into believing that they are flying at a higher altitude than they actually are due to the horizon appearing lower than it is. This can result in undershooting the runway and become a safety hazard. [5]
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In many places, laws restrict the use of heavily tinted glass in vehicle windshields; generally, laws specify the maximum level of tint permitted. Some vehicles have noticeably more tint in the uppermost part of the windshield to block sunglare.
In aircraft windshields, an electric current is applied through a conducting layer of tin(IV) oxide to generate heat to prevent icing. A similar system for automobile windshields, introduced on Ford vehicles as "Quickclear" in Europe ("InstaClear" in North America) in the 1980s and through the early 1990s, used this conductive metallic coating applied to the inboard side of the outer layer of glass. Other glass manufacturers utilize a grid of micro-thin wires to conduct the heat especially on the later European Ford Transit vans. These systems are more typically utilized by European auto manufacturers such as Jaguar and Porsche.
The use of thermal glass prevents some navigation systems from functioning correctly, as the embedded metal blocks the satellite signal. The RF signal tends to flow along the metal wires or layer so very little radiation can pass. This can be resolved by using an external antenna. Mobile telephones can also have problems; thermal glass typically allows only 0.001 (1‰, or one per mille) of the signal to pass, whereas a concrete wall with rebars allows up to 0.100 (10%, or 100‰) of the signal to pass.
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The term windshield is used generally throughout the US and Canada. The term windscreen is the usual term in the British Isles and Australasia for all vehicles. In the US windscreen refers to the mesh or foam placed over a microphone to minimize wind noise, while a windshield refers to the front window of a car. In the UK, the terms are reversed, although generally, the foam screen is referred to as a microphone shield, and not a windshield.
Sports or racing cars would sometimes have aero screens, which were small semi-circular or rectangular windshields. These were often mounted in pairs behind a foldable flat windshield. [6] Aero screens are usually less than 20 cm (8 inches) in height. They are known as aero screens because they only deflect the wind.[ citation needed ][ dubious – discuss ] The twin aeroscreen setup (often called Brooklands) was popular among older sports and modern cars in vintage style.
A wiperless windshield is a windshield that uses a mechanism other than wipers to remove snow and rain from the windshield. The concept car Acura TL features a wiperless windshield using a series of jet nozzles in the cowl to blow pressurized air onto the windshield. Also several glass manufacturers have experimented with nano type coatings designed to repel external contaminants with varying degrees of success but to date none of these have made it to commercial applications.
Certification of a windshield is necessary to ensure safety. Different counties have made different set of rule that all windshield manufacturers need to comply under Motor Vehicle Acts. Some of the most know certifications are US DOT, EU ECE, Chinese CCC, South African SABS and Indian BIS standards. These certification ensures safety, reliability and quality of a product as per respective legal requirements.
According to the US National Windshield Repair Association, many types of stone damage can be successfully repaired. Whether the windshield can be repaired always depends upon four factors: the size, type, depth and location of the damage. [7]
Repair of cracks up to 6.1 cm (2.4 inches) is within permissible limits; automobile glass with more severe damage needs to be replaced. However, this is dependent on local laws. If a crack extends to the edge of the panel then this would compromise the structural integrity of the windshield. Aircraft windshields are designed in such a way that even if a crack were to extend all the way across the panel, the structural integrity is maintained via multiple failsafe methods in both frame and the glass plies. A sacrificial outer layer that cracks rather than devitrifies is the first failsafe.
Circular bullseyes, linear cracks, crack chips, dings, pits and star-shaped breaks can be repaired without removing the glass, eliminating the risk of leaking or bonding problems sometimes associated with replacement.
Some damages are very difficult to repair, or cannot be repaired:
In cracked windshield repair, air is removed from the damaged area on the windshield with a specified vacuum injection pump. Then using the injection pump, the clear adhesive resin is injected to replace the air in the windshield crack. The resin is then cured with an ultraviolet light. When done properly, the damaged area’s strength is restored, as is 90–95% of the clarity.
Windshields that cannot be repaired have to be replaced. Replacement of a windshield typically takes less than an hour. To ensure the vehicle is safe to drive, time values called the Safe Drive Away Time have been established. Windshields which have been replaced must cure or bond sufficiently until they are able to withstand the forces of a crash. Knowing the minimum time needed to cure the glass bonding adhesives is therefore important. This safe drive away time (SDAT) or minimum drive away time (MDAT) refers to the time required until a windshield installation or glass replacement is considered safe to drive again. [8] Criteria are specified in U.S. Federal Motor Vehicle Safety Standards 212/208 (see FMVSS) to ensure the reliability of adhesive systems. Typically the SDAT is verified with crash tests as well as with high-speed laboratory test methods.
Consumers may be unaware that the MDAT or SDAT time is focused on safety and not necessarily on the quality, durability, or warranty of the installation. Care must be taken not to drive the vehicle prior to the SDAT/MDAT.
Airbags deploy at speeds up to 320 km/h (200 mph; 89 m/s) and in some cases exert tremendous force on the windshield. Occupants can impact the airbag just 50 ms after initial deployment. [9] Depending on vehicle design, airbag deployment and/or occupant impact into the airbag may increase forces on the windshield, dramatically in some cases. Forces of occupants on the airbags - and hence the potential forces on the windshield - are lower for belted occupants. [10] As consequence, adhesive suppliers usually inform their customers about the level of security achieved:
1) Example: Security exceeding FMVSS 212/208 belted
2) Example: Security exceeding FMVSS 212/208 unbelted [11]
With the advent of quick-cure adhesives, mobile windshield replacements have become more prevalent. Often the temperature and humidity cannot be controlled for mobile installations. For most common glass adhesives the ideal environment is 21 °C (70 °F) and 50% humidity. Variations from the ideal curing environment can increase the time needed for a sufficiently safe bond to form. Because of the variables and difficulties involved in mobile windshield replacement, many vehicle manufacturers do not recommend this method of installations.
Waste disposal of laminated glass is no longer permitted in a landfill in most European countries as the End of Life Vehicles Directive (ELV) is implemented. A study [12] by Surrey University and Pilkington Glass proposes that waste laminated glass be placed into a separating device such as a rolling mill where the glass is fragmented and the larger cullet is mechanically detached from the inner film. The application of heat then melts the laminating plastic, usually, polyvinyl butyral "PVB" enabling both the glass and the interior film to be recycled. The PVB recycling process is a simple procedure of melting and reshaping it. One possible method of recycling of simple automotive laminated windshields could involve heating the windshield to above the melting point of the PVB interlayer and then separating the glass plies. This depends chiefly on the differential melting points of PVB and glass and is not suitable for other interlayer materials such as silicone based materials.
An airbag is a vehicle occupant-restraint system using a bag designed to inflate in milliseconds during a collision and then deflate afterwards. It consists of an airbag cushion, a flexible fabric bag, an inflation module, and an impact sensor. The purpose of the airbag is to provide a vehicle occupant with soft cushioning and restraint during a collision. It can reduce injuries between the flailing occupant and the vehicle's interior.
A windscreen wiper or windshield wiper is a device used to remove rain, snow, ice, washer fluid, water, or other debris from a vehicle's front window. Almost all motor vehicles, including cars, trucks, buses, train locomotives, and watercraft with a cabin—and some aircraft—are equipped with one or more such wipers, which are usually a legal requirement.
AGC Inc., formerly Asahi Glass Co., Ltd.'(旭硝子株式会社), is a Japanese global glass manufacturing company, headquartered in Tokyo. It is the largest glass company in the world and one of the core Mitsubishi companies.
Lamination is the technique/process of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance, or other properties from the use of the differing materials, such as plastic. A laminate is a layered object or material assembled using heat, pressure, welding, or adhesives. Various coating machines, machine presses and calendering equipment are used.
Polyvinyl butyral is a resin mostly used for applications that require strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility. It is prepared from polyvinyl alcohol by reaction with butyraldehyde. The major application is laminated safety glass for automobile windshields. Trade names for PVB-films include KB PVB, GUTMANN PVB, Saflex, GlasNovations, Butacite, WINLITE, S-Lec, Trosifol and EVERLAM. PVB is also available as 3D printer filament that is stronger and more heat resistant than polylactic acid (PLA).
A window film, sometimes called tint, is a thin laminate film that can be installed on the interior or exterior of glass surfaces in automobiles and boats, and as well as on the interior or exterior of glass in homes and buildings. It is usually made from polyethylene terephthalate (PET), a thermoplastic polymer resin of the polyester family, due to its clarity, tensile strength, dimensional stability, and ability to accept a variety of surface-applied or embedded treatments.
An auto mechanic is a mechanic who services and repairs automobiles, sometimes specializing in one or more automobile brands or sometimes working with any brand. In fixing cars, their main role is to diagnose and repair the problem accurately and quickly. Seasoned auto repair shops start with a (Digital) Inspection to determine the vehicle conditions, independent of the customers concern. Based on the concern, the inspection results and preventative maintenance needs, the mechanic/technician returns the findings to the service advisor who then gets approval for any or all of the proposed work. The approved work will be assigned to the mechanic on a work order. Their work may involve the repair of a specific part or the replacement of one or more parts as assemblies. Basic vehicle maintenance is a fundamental part of a mechanic's work in modern industrialized countries, while in others they are only consulted when a vehicle is already showing signs of malfunction.
The pillars on a car with permanent roof body style are the vertical or nearly vertical supports of its window area or greenhouse—designated respectively as the A, B, C and D-pillar, moving from front to rear, in profile view.
Safety glass is glass with additional safety features that make it less likely to break, or less likely to pose a threat when broken. Common designs include toughened glass, laminated glass, and wire mesh glass. Toughened glass was invented in 1874 by Francois Barthelemy Alfred Royer de la Bastie. Wire mesh glass was invented in 1892 by Frank Shuman. Laminated glass was invented in 1903 by the French chemist Édouard Bénédictus (1878–1930).
Windshield washer fluid is a fluid for motor vehicles that is used in cleaning the windshield with the windshield wiper while the vehicle is being driven.
Tempered or toughened glass is a type of safety glass processed by controlled thermal or chemical treatments to increase its strength compared with normal glass. Tempering puts the outer surfaces into compression and the interior into tension. Such stresses cause the glass, when broken, to shatter into small granular chunks instead of splintering into large jagged shards as ordinary annealed glass does. These smaller, granular chunks are less likely to cause deep penetration when forced into the surface of an object compared to larger, jagged shards because the reduction in both the mass and the maximum dimension of a glass fragment corresponds with a reduction in both the momentum and the penetration depth of the glass fragment.
An automobile repair shop is an establishment where automobiles are repaired by auto mechanics and technicians. The customer interface is typically a service advisor, traditionally called a service writer.
Laminated glass is a type of safety glass consisting of two or more layers of glass with one or more thin polymer interlayers between them which prevent the glass from breaking into large sharp pieces. Breaking produces a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass.
The Federal Motor Vehicle Safety Standards (FMVSS) are U.S. federal vehicle regulations specifying design, construction, performance, and durability requirements for motor vehicles and regulated automobile safety-related components, systems, and design features. They are the U.S. counterpart to the UN Regulations developed by the World Forum for Harmonization of Vehicle Regulations and recognized to varying degree by most countries except the United States.
Vehicle glass is glass used to provide light access to motor vehicles. It includes windscreens, side and rear windows, and glass panel roofs.
Triplex Safety Glass was a British brand of toughened glass and laminated glass. Their marque is often seen on vehicle and aircraft windscreens.
Belron International Limited is a British vehicle glass repair and replacement group operating worldwide across 34 countries and employing over 25,000 people. Headquartered in Egham, Surrey, United Kingdom, Belron's brands include Autoglass in the United Kingdom, Ireland, and Poland, Carglass in most of Europe, O'Brien AutoGlass in Australia, Safelite in the United States, Smith & Smith in New Zealand, and Lebeau and Speedy Glass in Canada.
Composite glass is the collective term for a laminate having at least two glass panes which are in each case connected by means of an adhesive intermediate layer composed of plastic, e.g. by means of a casting resin or a thermoplastic composite film, which is highly tear-resistant and is viscoelastic. Composite glass should not be confused with composite windows.
Adhesive bonding is a joining technique used in the manufacture and repair of a wide range of products. Along with welding and soldering, adhesive bonding is one of the basic joining processes. In this technique, components are bonded together using adhesives. The broad range of types of adhesives available allows numerous materials to be bonded together in products as diverse as vehicles, mobile phones, personal care products, buildings, computers and medical devices.
NordGlass, is a Polish manufacturer of windshields for the repair of passenger cars and trucks, work machinery, railways, ships and military. Headquartered in Koszalin, it has 2 plants: Koszalin and Słupsk, employs over 1,000 employees, has a nationwide network of repair and replacement of car windows. Since 2015, it is a subsidiary of AGC Inc. – the largest glass company in the world and one of the core Mitsubishi companies.