60 Section 1 Introduction to Collision Repair
Magnesium
Magnesium is lighter than aluminum, but it is just
as strong. Parts made of magnesium include the radiator
support for some pickup trucks and the instrument panel
support in another type of pickup truck. Damaged magne-
sium parts should be replaced, not repaired. Never heat
or weld a magnesium part, as the metal can catch fire.
Plastic
Many vehicle parts are made of plastic. Plastic
components are lighter and more corrosion resistant
than steel components. Plastic can be broken down into
three general categories—flexible, semi-rigid, and rigid.
Flexible plastic can be easily distorted and returned c
to its normal shape after the pressure is released. See
Figure 3-9. Flexible plastic is used on bumpers and
ground effects. Flexible plastic can stretch and tear
when damaged. Flexible plastic can dent. Highly curved
and harder areas of a flexible plastic part, such as the
corners of a bumper cover, may be pushed in and not
pop back, creating a dent.
Semi-rigid plastic can be distorted, but not as easily c
as flexible plastic. It, too, will return to its normal shape
after the pressure is released. If the force is great, a semi-
rigid plastic part will break. Radiator fan shrouds and
fender liners are generally made from semi-rigid plastic.
Rigid plastic is the least flexible type of plastic. This c
type of plastic will move little, if at all, before breaking.
Rigid plastic is used to make rear hatches, doors, hoods,
and cowl vent panels.
Glass
Glass can be much more than just a window. The
glass used in a unibody vehicle is designed to strengthen
the unibody. Glass can be classified as either fixed
or movable. Fixed glass is set in place and cannot be
opened. Windshields and back glass are examples of
fixed glass. Most movable glass rolls up and down, but
some van windows have glass that opens out.
There are two types of automotive safety glass: lami-
nated and tempered. Laminated glass is made of two s
layers of glass with a layer of plastic in between them.
Laminated glass is used for windshields. The plastic layer
resists penetration and holds pieces of broken glass in
place, helping to prevent injury. Figure 3-10 shows what
broken laminated glass looks like.
Tempered glass is a single layer of glass and is
used on all windows except the windshield. It is harder
than laminated glass and can withstand greater impacts.
When tempered glass breaks, it shatters into small
pieces, or shards, rather than long, jagged pieces. See
Figure 3-11. The small pieces are less likely to cause
injury to a vehicle’s occupants.
Vehicle Parts
This section identifies the body parts of various types
of vehicles. Keep the following in mind when reading
about these body parts:
Left and right are always from the perspective
of sitting in the driver’s seat. The driver’s side of
the vehicle is the left and the passenger’s side is
the right.
Figure 3-8. Stamped sheet aluminium, aluminium
alloy extrusions, and aluminium castings make up this
unibody structure. A special rivet-bonding technique is
used to connect the various part components. (Jaguar)
Figure 3-9. This flexible plastic bumper can be
distorted without damage.