The apparent rapid development in automotive design and performance effects glass which is one of the major components of motor vehicles. Glass has become to specify the structural, mechanical, aesthetic, environmental and quality performance of the vehicle it is mounted, much more than ever. In the last decade, glazing in vehicles have extended by area, all glass forms have become complex, the number of parts assembled to glass has increased and permitted failure size and concentration have been decreased.
As the automotive industry calls for more from glazing, being well-informed about the usage and features of glass gains ground. The following information, given by Turkey 's leader auto glass producer Trakya Cam Automotive Glass Plant, mainly aims to inform all the experts and implementers about automotive glazing in original equipment market.
A. Production
How is the auto glass produced?
As they are one of the most significant parts of the automobiles, automotive glasses are special in terms of safety and appearance.
On processing side, auto glasses' most important feature is that they are produced via brief pressing or sag bending.
Raw Glass
Please see http://www.trakyacam.com.tr/TrakyaCam/en/teknoloji.htm for the production technology of float glass.
Float glass supplied to automotive, should be at the best quality to fulfill the expectations of the original equipment market in terms of optical quality, melting based failures and thickness tolerances.
Tempered Glass
Tempered glass is used for side and rear windows for motor vehicles. By the tempering process, glass' mechanical endurance is strengthened and the cracking behaviour is modified to reduce the risk of injury in case of an accident.
Side and rear windows to be tempered are cut from the float glass panes of the required thickness on CNC cutting tables. Later on the glasses are edge worked and printed . The glass is, then heated up until the softening temperature and cooled instantly with compressed air to give it strength. This glass is shipped for secondary processes after being inspected in terms of strength, optical quality and visible faults.
Through secondary processes, subparts are assembled in accordance with the demand of the clients. Apart from these, primer applications, fixing with polyurethane applications, moulding application encapsulation and connector solding is done.
> Production of tempered side and rear windows
Laminated Glass
Laminated glass, which is the standard of windshields, can also be used in side and rear windows.
Laminated windshields, besides being produced to avoid accidental injuries resulting from head impacts, are also bound to comply with the superior quality provisions.
Production of laminated glass generally starts with cutting two panes of 2.2mm float glass on CNC cutting tables. Edge worked glasses are screen printed as requested and the dried glasses are washed to be ready for combination. For combination, highly pure 0.76 mm polyvinyl butyral layer, suitable for automotive standards, is placed in between two glass panes in the circumstances of a very clean room.
The gained three layered laminate becomes a laminated windshield after being autoclaved under high temperature and pressure. As secondary processes, mirror base and rain sensor bracket gluing processes, assembly of the locator pin and primer applications are applied on optically tested glasses.
> Production of laminated windshields
B. Properties
Safety properties
The basic feature of automotive glazing is to provide a safe journey to the passengers in the vehicle. In case of an accident, if the passengers or some external objects collide to the windshield, laminated glass decreases collision energy by absorption and prevents broken glass injuries.
Laminated windshield, through the elastic inter layer between the glass panes attenuates any possible head crashes, prevents possible injuries by keeping splinters in place when broken and also prevents the ejection of the passengers from the windshield.
Tempered sidelites and backlites, besides withstanding the forces during door closures, also break into small blunt fragments in case of an accident and prevent injuries.
Optical properties
One of the most significant features of automotive glazing is its optical performance. Optical distortion, double sighting, light transmission and color distinction capacity should be flawless at especially windshields and front side windows that are in the driver's sight.
Besides these basic features the glass' resistance to abrasion, endurance to the sun's ultraviolet rays, high temperature and moisture, capacity to defrost and demist and positioning performance to the vehicle have to be provided at most level via accurate tests and process control tools.
These features of automotive safety glasses that concern personal safety must be guaranteed by the glass producer according to ECE R43 international specification and European Union Regulation.
Comfort properties
Modern automotive glazing is asked to supply the comfort of the passengers as well as their safety. With their new facilities, automotive glasses enable auto designers to decrease the UV damage, create a bright interior, prevent the interior to be seen from the outside, block engine noise and structural vibration, provide antenna function for GPS, GSM, radio etc. and present the driving info to the driver at his sight level.
Contribution to vehicle design
High motor power, comfort, low fuel consumption and low emission have begun to be the main purchasing criteria for customers as new automobiles are more speedy.
In parallel to these trends, automotive glazings decrease solar heat gain in the car, thus reduce the need for air conditioning and decrease the engine strain and the emission, assist to the structural power of the vehicle and help lowering the aerodynamic breaking and reduce the wind noise.
Quality elements
In addition to the functions mentioned above, automotive glazings gradually progress in meeting high expectations of customers by form and visual quality. For example, as auto glasses are extended by area and have more complex forms, the permitted size and bending tolerances and the number and size of acceptable surface and structure defects are decreased, too.
Therefore, the accuracy performed all through the production process should continue afterwards and care should be taken to avoid glass scratches.
C. Instructions for use
In this section, the instructions that should be followed during the utilization of the auto glasses can be found.
Handling
Although being a very hard material, glass can unfortunately be easily scratched by another piece of glass. Automotive Glasses, usually being large and heavy and being packed tightly lead to crashes among themselves during manual processes and cause damages on the surface.
Another kind of common damage is chipping which occurs when the side of a glass pane hits to a hard surface. According to its place and depth, chipping causes aesthetic errors or decrease in strength.
Besides slight hits, any friction of glass with metal, ceramic and even plastic surfaces may cause scratches on glass. According to the location and depth of these scratches or scrapings, glass may be classified as damaged and wouldn't be used.
In addition to surface damages, any stain that may occur during handling is another cause of customer dissatisfaction.
Therefore glass shouldn't contact with hard and dusty surfaces and shouldn't be hit to other glasses and objects during handling process which include being taken out of package, being carried, being prepared for assembly and being executed additional processes by the line.
Packaging
From time to time, besides Trakya Automotive Glass, for various reasons the customers need to do the packaging and transportation themselves. If the packaging is not done properly, reclamations such as scratches, scrapings, chippings and etc. might occur on the shipped glasses because of logistic reasons.
Glass packaging is important for the glass to be transported without any damage and breakage. Laminated glasses should be placed inside the crates, that are produced peculiarly for glass transportation, without letting them touch each other or other hard surfaces and move from their place during rattling and stretching. The crate should be tied in appropriate tightness, loaded by a forklift to the truck gently and fixed to the truck. During loading, the crates should never be stepped on and glass should not be exposed to water, dust or mud.
Stocking
Despite being a hard and durable material, glass is easily affected by water, dust, friction and impact. Therefore, the eligibility of the customers' stocking field is very important. The glass that gets dusty at the stocking field might be scratched while cleaning. Glass that is not installed to the vehicle should not be kept in open air exposed to rain, sun and dust. Instead, it should be kept in a fresh aired storeroom, without being exposed to sudden temperature changes.
Assembly onto the Vehicle
Automotive Glasses is installed to the vehicle via a seal or gluing process.
Glass is transported in metal, plastic or wooden crates that are specially designed and produced in accordance with the properties and form of the glass and the size of the subparts on them. The crates carrying door glass, backlite glass, quarter glass and windshield should be taken to the assembly area in their original packages and opened carefully.
The damage on glass is a situation frequently encountered at assembly area or during assembly. Glass should not be robbed against each other or to other surfaces, should not be wiped with dusty and oily cloth and unnecessary transfer should be avoided in the assembly area. If transfer is a must, the glass pane should not be removed from the middle of the package instead the panes in the front should be moved to another crate carefully.
The separation material (paper, cardboard, etc.) between the door glasses should not be taken out all together but one by one at the assembly area. There should not be a second stock place close to the assembly area because that increases the risk of scratches on the glass. It should be noted that tempered glass that is exposed to hits and overloading by the operators may get broken.
Windshields are sensitive to chipping since they are not strengthened. During assembly chipping might occur as a result of hitting the windshield to the hard surfaces. It should be noted that windshields should not be hit while bonding as it may cause cracking.
The faults on the glass panes have to be marked on the assembly line. These glass panes must be wrapped in their original package to avoid additional faults and should be transported to the quarantine area and must be kept there up until the analysis of the technical representative of the customer. Glass that does not have the approval sticker of the technical staff should not be sent to the plant.
How to use
Automotive glass should be well cared even after the vehicle is presented to the final user.
It will elicit to keep their functions and aesthetical values for a long time not to;
• clean the outer surface of the Automotive Glasses with corrosive cleaning agents,
• let dust accrue in the seals of the front door,
• use corrosive cleaning agents that may detach the resistance lines on the heated rear windows and,
to do the cleaning parallel to the resistance lines while avoiding glass from any kind of impact.
When replacement of a broken automotive glass is necessary, a spare automotive glass which has the high quality of an original equipment market and an E mark signifying its coherence to ECE R43 should be requested for the safety and comfort of the passengers.
