Ford Fiesta (2011 year). Manual — part 99

NOTE: The identification of the type of plastic is
necessary for the plastic welding process in order
to determine the correct welding rod (welding
material) to use.

If an identifier is missing or cannot be made out,
the following easy to perform tests will help:

Visual Inspection

Visual inspections mainly serve to identify PUR
and GRP materials. Thermoplastic components
are often painted and are therefore difficult to
identify.

Identification characteristics:

• When PUR cracks or similar damage occurs,

pores of foam can be seen.

• GRP can be recognized by the glass fiber

structure on the inside.

Mechanical test:

The plastic group can be determined by a sound
test:

• Degree of hardness - the higher-pitched the

sound, the harder the plastic.

• Elasticity - the more muffled the sound, the

higher the elasticity of the plastic.

Sanding test

In this a place is chosen which will not be visible
later, and the finger belt sander is used to sand the
plastic.

The plastic group can be determined using the
pattern of the dust:

• Thermosets produce a white dust.

• Thermoplastics smear and do not produce dust.

Float test in water:

Take a small piece of plastic from the component
to be repaired and test whether it floats on water
(PP-EPDM, HD-PE, PP) or sinks (PVC/U, PVC/P,
ABC, PC).

Nature of the surface

The surface of plastics can be categorized as rigid
(PVC-U, PVC-P) and waxy (PP/EPDM, HD/PE,
PP).

Adherence test using welding rod

Heat a welding rod that is identified with the type
of material and the plastic component using the
hot air gun. Press the welding rod onto the plastic
component to be welded. When the welding rod
cools down, if it remains stuck to the component
or can only be removed with great difficulty, then
it can be assumed that the two are made of the
same plastic. When pulling away from PP/EPDM,
HD/PE and PP, this can lead to strings.

CAUTION: Danger of poisoning! When
burned, most plastics release vapors
harmful to health. Ventilate the room well
and use respiratory protection. Where
possible work using an extraction system.

Burning test

Every plastic has a characteristic behavior and
smell when burned. Using a knife, cut off a small
piece from the component to be repaired, remove
any dirt and paint residues and set light to the small
chip. Now observe the burning behavior. Compare
the color, type and smell of the smoke with the
results from the following table.

Plastic recognition using a

burning test

Short

descrip-

tion

Blackish smoke, the material drips

like a candle when burning and

smells like wax.

ABS

No smoke, draws filaments, smells

like burnt horn.

PA

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Plastic recognition using a

burning test

Short

descrip-

tion

Yellowish, sooty smoke. Smells

sweetish.

PC

No smoke, the material drips like a

candle when burning and smells like

burnt oil.

PP

No smoke, the material drips like a

candle when burning and smells like

burnt oil.

PP/EDM

Hard and shiny, burns yellow, fluffy

soot.

PC/PBT

Blackish smoke and acrid smell.

Hard PVC
/ soft PVC

Safety instructions

In addition to the general safety instructions, the
relevant regulations and accident prevention
legislation must be observed.

NOTE: Without exception, before starting work you
must read the safety and warning instructions in
the chapter "Safety Instructions". In addition, pay
attention to the warning instructions of the particular
equipment manufacturer.

Information sheets, safety notices and guidelines
for the processing of adhesives containing
isocyanate, polyester resin, adhesives, solvent and
thinners provide more details on their use.

The following instructions must always be followed:

• Polyester resin, adhesive, solvents and thinners

are inflammable and must not be used near
naked fire or flames.

• Sawing and grinding operations must only be

carried out in rooms equipped with extraction
systems.

• If no rooms with extraction systems are

available, only use tools with extraction
equipment.

• Protective equipment such as gloves, protective

goggles, aprons and breathing masks are
essential.

Because of the various compositions of plastics,
repair work to plastic parts involves a variety of
repair methods.

The following methods are used:

• Thermoplastic straightening.

• Plastic welding.

• Plastic adhesive bonding.

• Plastic lamination techniques.

Thermoplastic straightening

Damage to thermoplastics can be rectified by
heating using the hot air gun (temperature about
100°C) while the deformation is pressed out until
the shape is regained.

Plastic welding

Splits formed in plastic bumpers are typical
possible plastic repairs.

NOTE: Do not carry out plastic welding in the area
of fixed foam backing. The foam backing will
usually be destroyed and the function of the
component is then no longer guaranteed.

If repair using adhesive methods is not possible
because of unfavorable conditions at the rear of
the repair location, plastic welding is a possible
repair process.

There are two methods of welding: hot air draw
welding and hot air fanning welding.

Plastic welding set

Description

Item

Various welding rods

1

Scraper (heart-shaped)

2

Hot air blower (approx. 1500 W)

3

Clamps

4

Welding nozzles

5

In addition to the components listed, plastic welding
requires tools already found in the workshop such
as scrapers, sanders, face cutters etc.

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As with all other welding processes, only certain
material combinations can be joined together using
plastic welding.

NOTE: Basic and in-depth training is offered on
the following topics. You will find an overview of
the complete range listed in the Training brochure
published by the Ford Service Organization.

NOTE: The manufacturer's data must be taken into
account when choosing welding materials and the
correct temperature setting of the hot air gun.

Repair sequence during plastic welding:

• To prepare the location for welding, remove

paint residues and sand the weld area.

• If parts of the material have been pushed in by

an impact, the damaged area can be brought
back to shape by heating.

• Drill out the ends of the split to stop it spreading

further. Machine the location of the weld into a
90° V-shaped groove, to accept the welding rod.

• Lay the welding rod in the groove.

• Perform the welding. Hot air draw welding or

hot air fanning welding.

• Rework the weld seam. After cooling, sand the

raised weld seam.

• Clean the sanded repair surface using plastic

cleaner. Apply plastic primer thinly to the repair
surface and paint it.

Despite good preparation and the correct choice
of welding materials, weld faults may occur.

The following points must be noted when welding
plastic:

• Weld together like with like:

– With very few exceptions, only the same

materials can be welded together, e.g. PP
with PP.

• Correct temperature:

– The correct choice of temperature is

important for the success of the repair. The
plastic must be warmed until it plasticizes
(dough-like, soft).

Guideline values for welding temperature:

Temperat

ure

Plastic

Brief

descrip-

tion

360°

Acrylonitrile butadiene

styrene copolymer

ABS

400°

Polyamide

PA

Temperat

ure

Plastic

Brief

descrip-

tion

370°

Polycarbonate

PC

280°

Polypropylene

PP

280°

Polypropylene/ethylene

propylene diene

copolymer

PP/EPDM

300°

Polyurethane

PUR

340°

Polyvinylchloride

Hard PVC

370°

Polyvinylchloride

Soft PVC

• Even pressure:

– When rod welding, the pressure is applied

by pressing on the welding rod.

• Steady speed:

– To achieve a good weld, care must be taken

that the working speed is steady.

Possible causes of weld faults:

• Deformation caused by overheating of the repair

area or tensions in the material while welding
the component.

• Plastic material too thin.

• Poor weld joint because the weld temperature

was too low or the welding speed was too fast.

• Welding different materials together.

• Weld seam dropped because the split gap was

too wide or the welding temperature was too
high.

A good weld is recognized by a slightly raised,
smooth and even weld bead on the surface of the
component.

The weld bead must only be worked once it has
fully cooled down.

Plastic adhesive bonding

Adhesive bonding of plastics has some advantages
over welding methods:

• Within the group of thermoelastic plastics, all

semi-rigid ancillary components (such as
bumpers, front grilles, etc.) can be repaired
without identification.

• A two-component polyurethane based adhesive

is used for all thermoplastic parts.

• Reinforcement strips can be attached behind

splits (split length up to max. 100mm) and

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openings to ensure the original strength
properties.

Tools and equipment also familiar from paint
repairs can be used in making adhesive repairs to
thermoplastic components.

Angle grinders and belt sanders can be used to
grind out scratches and splits. Orbital sanders with
extractors are used for fine sanding.

The infrared heater is used to provide fast and
certain drying throughout.

Plastic adhesive set

Description

Item

2-component adhesive

1

Cartridge gun

2

Mixing tube

3

Apart from the components shown, other materials
may be needed to bond plastics, depending on the
repair position.

For large scale repairs, it may be necessary to
insert reinforcement panel strips and reinforcement
matting as fixing aids.

Repair sequence during plastic adhesive bonding:

NOTE: Follow the manufacturer's guidelines when
using adhesives.

• Prepare the location of the bond. Remove paint

residues and sand the area to be bonded. Drill
out the ends of the split to stop it spreading
further. Prepare the bond location into a
V-shape and clean it with plastic cleaner.

• Apply the adhesive. The two-component

adhesive is applied to the cleaned and primed
repair location using a hand gun. Spread and
smooth the adhesive using a flexible plastic
spatula.

• Rework the bond location. After cooling, sand

the raised adhesive. Clean the sanded repair

surface using plastic cleaner. Apply plastic
primer thinly to the repair surface. Apply paint.

GRP repairs

GRP material is hard and brittle in its strength
properties. Because of these material properties,
splits and openings often result in cases of serious
damage.

The stability of GRP parts is impaired if the glass
fiber reinforcement is cracked. The component
must be replaced in cases of serious damage that
affect the structure.

Minor damage (such as abrasion, splits up to
80mm, holes up to approx. 60mm diameter, etc.)
can be repaired to a technically and visually perfect
standard, provided that the damage does not occur
in heavily used or hard-to-reach areas.

To ensure perfect repair results, observe the
following points:

• The room temperature should be at least 15°C

and the air should be as dry as possible.

• The repair location must be thoroughly dry and

clean.

• Before the repair, the GRP part being repaired

must be dried using an infrared heater or in a
drying oven.

• In cases of large splits and fractures, the

strength of the outer skin can be re-established
by backing with a reinforcement material.

Tools and equipment from the paint shop can be
used to carry out repairs to GRP parts. Angle
grinders and belt sanders can be used to grind out
scratches and splits. Orbital sanders with extractors
are used for fine sanding.

GRP repair set

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