Direct Glazing

Direct Glazing

HOW TO: DIRECT GLAZING


The windscreen is a very important component with respect to the overall structure of the car body. It serves to improve the structural stiffness of the car and provide better protection to passengers. Adhesive is the only means of holding the windscreen to the car body.

Further information about safety, direct glazing methods and test standards is provided below:

 

Crash tests and product requirements

Lightweight construction and torsional stiffness

Multifunctional glazing

Design functions

Direct Glazing: Additional Knowledge

Learn everything you need to know about the subject of direct glazing.

Henkel direct glazing adhesives offer high safety standards as a result of many years of active research and OEM experience.

  • All premium direct glazing products from the TEROSON range are proven by realistic crash tests and certified by the TÜV Rheinland test authority.
  • The production process and quality are constantly monitored by TÜV Rheinland.

The windscreen absorbs some of the energy caused during a crash and keeps the passenger airbag in the right place. To ensure passenger safety in accordance with the safe drive-away time of the vehicle, the adhesive must provide proven hold for the windscreen in place in the event of an accident.
Safe drive-away times depend on the cure and inner strength of the direct glazing adhesives.

Curing process

One-component product

Two-component product

3-4 mm cure in the first 24 hours at 23°C with 50 % relative humidity.

 

One-component polyurethane direct glazing adhesives cure at room temperature and humidity.
Skin formation: 3-4 mm in the first 24 hours at 23°C and >50% relative humidity.

Cure: Chemical reaction of components A & B
Henkel two-component PU is fully curey within two hours.

Two-component polyurethane direct glazing adhesives cure due to the chemical reaction of components A and B. Complete bead curing is independent of humidity and air temperature (for the cure speed, see the product's technical data sheet).

 

The improved standard safety test is approximately four times more rigorous.

All Henkel direct glazing products are tested in accordance with one of these following two standards.

Test standard for safe drive-away times of direct glazing adhesives:
FMVSS = 50 km/h and 100 % frontal impact or European standard = 64 km/h and 40 % overlap.

US standard (FMVSS 208/212)
(50 km/h, 100 % frontal impact collision).

Improved crash test standard
(64 km/h, 40 % overlap) = 40 % of the width of the widest part of the car (not including wing mirrors).

The load-bearing components of a car body (the parts highlighted in orange) are special supporting pillars with high strength and stiffness. Lightweight vehicle body designs use thinner steel panels to reduce the vehicle weight.
Safeguarding the overall torsional stiffness of the body means placing greater demands on the windscreen. The windscreen thus helps to ensure the stiffness of the vehicle body.


Direct Glazing adhesives can improve structural rigidity by up to 40 %

The car's windscreen in combination with a strong (high-modulus) direct glazing adhesive makes a critical contribution to the overall torsional stiffness of the car body.

The high shear modulus of the adhesive (>2.5 MPa) enhances the torsional stiffness of vehicle bodies.

A high-modulus direct glazing adhesive is highly recommended to prevent corrosion. Using low-modulus products cause stress in bondlines and may even cause welding points to break. Corrosion can set in quite soon inside the chassis and may go undetected. Any corrosion reduces the stability of the chassis.

Definition of shear modulus:

A measure of the inner strength of an adhesive (measured in MPa) in relation to the elongation of 10 % (G10) or 20 % (G20).

Henkel direct glazing products specified as HM (high-modulus) have a shear modulus strength in excess of the 2.5 MPa recommended by most car manufacturers.

To ensure the correct functionality of integrated car antennas and heating systems, a direct glazing adhesive with low conductivity is highly recommended.

Low-conductive direct glazing adhesives are recommended by most car manufacturers. See product feature HMLC (high modulus low conductivity).

Protection against galvanic corrosion and contact corrosion on aluminium car bodies.

A bus-rod touched by an electrically conductive adhesive allows electric current to pass through it. Paint adhesion will be affected and humidity penetrates underneath, causing corrsion.

No influence on the reception quality of radios, TV, mobile phones, the internet and navigation systems, etc.

Definition:

Electrical conductivity

•  A measure of the ability of a material to conduct electric current.
• The lower the conductivity, the higher the insulation resistance.
• Measure in Siemens/cm (e.g. 10-10)

Electrical resistance
•  A measure of the ability of a material to offer resistance to the flow of electric current through itself.
• The higher the resistance, the better the insulation performance.
• Measured in Ohm x cm (e.g. 1010)

Evolution of installation methods for car glazing components such as the windscreen, rear window and side screens.

Rubber-mounted system
Windscreen mounted and sealed
with a moulded rubber gasket,
e.g. on trucks, buses, excavators.

Butyl-taped system
Adhesive butyl tape is used
to attach the windscreen
to the body flange.

With the help of modern adhesives, Henkel offers ist customers improved direct glazing solutions that provide numerous advantages over older application methods.

Polyutherane-bonded windscreens
PUR adhesive is used to bond the windscreen to the flange, thereby achieving a 100 % seal.

  • Maximum passenger safety thanks to correct airbag deployment
  • Significantly improved torsional stiffness
  • Improved aerodynamics due to flush fit of window/body