Identifies the differences between Laminated and Toughened glass used in the construction of motor vehicle. Also glazing used for HUD graphical displays

2. 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.

3. Glazing Types
 Laminated(non-tempered):
used for windscreens
 Toughened/Tempered:
drop glass, side fixed glass
and rear screens.

4. Laminated
 Normally 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.

5. 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.

6. 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.

7. Toughened/Tempered Glass
 This 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.

8. Toughened/Tempered Glass
It 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.

9. 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.

10. 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.

11. HUD Windscreen

12. 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.

13. HUD Cross Section

14. THE MOT
 Depending 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.

15. 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.

16. Glazing Repair Standards
 BS AU 242:1998.
 BS AU 251:1994.

17. BS AU 242a :1998
 BS 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.

18. BS AU 251:1994
BS 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.

19. 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.