Vehicle Glazing

Automotive Glazing Systems Processes

Increasingly, glazing systems rather than a simple piece of glass are being supplied to the vehicle manufacturers.

Much of this value-added activity is undertaken once the glass has been laminated or tempered.

Glazing systems help to simplify the vehicle assembly process.

Modular systems such as encapsulation and extrusion are designed to facilitate adhesive bonding of the glazing to the vehicle.

Glazing TypesLaminated(non-

tempered): used for windscreens

Toughened/Tempered: drop glass, side fixed glass and rear screens.

LaminatedNormally used for a

vehicle's windshield, in the case of breakage, the glass is held in place by the interlayer, retaining emergency visibility for the driver.

Laminated

Normally two thin glass plies create a sandwich around a polyvinylbutyral (PVB) interlayer.

Usually the glass plies are shaped (curved) as matched pairs through heating to a temperature of around 620°C. 

Laminated The shaped glass pairs are then gradually cooled to room temperature before the PVB laminate is sandwiched between them.

After a further heating (140c) and removing of air via vacuum /squeezing the process is complete.

Toughened/Tempered GlassThis is made possible by the toughening

process which introduces internal stresses into the glass through a combination of controlled heating to very high temperatures, (>640°C) and differential cooling.

The heating cycle is also used to shape or curve the glass, either by allowing the heated glass to 'sag' to a pre-defined mould shape under gravity, or for more complex shapes, by being pressed to shape by male and female moulds.

Toughened/Tempered GlassIt is designed to be much stronger than non-safety glass. it shatters into very small pieces rather than sharp shards of glass, thereby significantly reducing risk of injury.

Encapsulation

Encapsulation involves the injection moulding of a polymer trim, shaped precisely to fit the vehicle body, to the periphery of the glazing. It also provides the opportunity to incorporate within the moulding additional styling features, fixing mechanisms and even hinges for opening windows in minivans and estate cars.

Extrusion

An alternative glazing system is provided by the robotic extrusion of a polymer profile to the periphery of the glazing, with the extruded profile or seal being precisely shaped to the vehicle.

HUD Windscreen

HUD Screen

Standard windshields cause projector images to appear as double images due to the inflection of light.

HUD windshields control for the inflection of light by adopting a wedge-shaped cross-section and enable images to be projected clearly.

The film for HUD thus enhances visibility and contributes to a more comfortable and safer driving experience. 

HUD Cross Section

THE MOTDepending on where it is located, some

windscreen damage will result in an MOT failure if not attended to.  The screen is divided into two areas for the purposes of the MOT.

The ‘A’ Zone

The 'A-zone' in front of the driver

(The 'A-zone' – a 290mm wide band centred on the steering column and bounded top and bottom by the wiper swept area) – damage larger than 10mm across will normally result in a failure.

Elsewhere on the windscreen – damage larger than 40mm across will normally result in failure.

Glazing Repair StandardsBS AU 242:1998. BS AU 251:1994. 

BS AU 242a :1998BS AU 242:1998. This is a code of practice

governing the types of damage that can be repaired and their location on the windscreen.

You must use equipment that has passed BS AU 251:1994 to comply with BS AU 242:1998.

BS AU 251:1994BS AU 251:1994. This standard is a performance standard for windscreen repair equipment.

Repairs are tested to the same performance standards as original windscreens for strength, optical performance and resistance to climatic effects. 

WARNING!These tests are for windscreen repair

systems including their chemicals. They are NOT a test for a stand-alone resin. This means that mix and match systems will

not be suitable for repairs to national standards.