The aim of this presentation is to provide a consistent test/fail guideline for light and heavy vehicle inspections that are in line with the RTA Guide.

1. Structural Damage & Maintenance
– Day 2

2. 2
Presenter Background
(Enter summary of presenter skills
and work history)
Content for this slide will be
entered by the Trainer.

3. FIRE PRECAUTIONS HEALTH AND SAFETY COFFEE BREAKS
RESTROOM BREAKS NO MOBILES NO SMOKING
Make sure all safety equipment discussed in the course are available
for demonstration.
3
Ground Rules

4. 4
Course Objectives
The aim of this presentation is
to provide a consistent test/fail
guideline for light and heavy
vehicle inspections that are in
line with the RTA Guide.

5. 5
Learning Outcome
At the conclusion of this course
delegates should be able to:
Identify the different designs used
by vehicle manufacturers to ensure
occupant protection.
Understand the use of new material
technology used within vehicle
manufacturing.
Understand modern repair practices,
methods and procedures inclusive of
equipment used.
Be able to recognise poor repair
practices carried out inclusive of
chassis, outer body and joining
methods used.

6. • Joining methods carried out on
all material types used in
vehicle construction
• The effects of heat on materials
and how to recognise potential
damage and weaknesses
• Equipment used for joining
inclusive of welding machines
• Recognising a variety of welding
faults and poor welding methods
• Practical session to observe and
take part in welding procedures
6
Day 2
Agenda

7. Joining
One of the most important and
critical aspects of repair is the
joining method. Joints can be
either welded, bonded, riveted or
mechanically fastened.
In some cases a variety of the
above can be used together
depending on the manufacturer's
repair method.
For example a roof panel may have
been welded using a laser during
manufacture but the repair method
may state that the replacement is
bonded and riveted with no
welding at all.
7

8. Welding still remains one of the
main joining processes used
within the manufacture of light
vehicles, heavy, bus and other
forms of transit.
Welding processes remained
relatively unchanged for many
years as the manufacturing
process in terms of material used
saw little change as well.
However, within the last 10 years
much has changed.
As discussed previously, the
materials used for manufacturing
have changed significantly which
has also lead to huge changes in
welding processes.
Joining
8

9. Oxy acetylene welding was used for many years for steel welding,
brazing, cutting and heating.
Joining
9

10. When welding with oxy acetylene
the temperature at the tip
(flame) is equal to 3200 degrees
centigrade.
The use of such heat damages high
strength steel irreversibly.
Brazing with oxy acetylene can
also cause corrosion through the
use of fluxes.
Joining
10

11. Joining
Brazing has been carried out
using oxy acetylene.
The heat will have damaged the
material at molecular level and
the flux used will aid corrosion.
This process should never be
used.
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12. Heating
Oxy acetylene torches should
never be used as an aid to
carrying out repairs.
High strength steels will start
to become damaged at temperatures
of 1200 and degrees and higher.
Some materials will be damaged at
lower temperatures.
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13. Heating
13

14. Heating
14

15. Out with
the old
Joining
Welding equipment has changed significantly within the last 10 years
and continues to do so.
In with the
new
15

16. Resistance spot welders recommended for use by vehicle manufacturers
within the aftermarket have to be able to perform a variety of welding
functions and be able to work across a wide range of steels.
Joining
16

17. A typical resistance spot welders interface is highlighted here.
Joining
Be able to set up
for different
materials.
Be able to
set the tip
pressure.
Be able to
set welding
times and
power levels.
Have on board
manufacturers
pre determined
settings.
17

18. Joining
10 years ago the “tip” pressure was a manual setting.
Now a particular amount of force is required to be used with different
materials to help achieve perfect welds.
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19. Joining
Most manufacturers would recommend a power rating of at least 12000 or
more amps.
Huge power output centred at a precise point to limit heat migration
and also to create a manufacture sized weld nugget.
19

20. This process is used for welding
alongside resistance welding.
Can be used for both steel and
aluminium.
These machines also have to have
specific ratings as recommended
by manufacturers for use in the
aftermarket.
For example, machines used for
aluminium welding should have a
minimum 270 amp rating.
GMAW-Gas Metal Arc Welding
Joining
20

21. The correct welding process is
critical and if this differs to
manufacturers standards then the
likely outcome is an unsafe
vehicle.
If the vehicle does not perform
as it was designed to do then
this clearly put lives at risk.
Joining
This example clearly
highlights inadequate welding
carried out on a vehicles
chassis.
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22. Joining
It is good practice to apply
underbody coatings that are
removed or damaged.
Some bodyshops will use these
coatings to hide poor repairs. To
the untrained eye everything will
appear normal.
A total disregard to health and
safety in this example.
If you don’t worry about yourself
are you going to worry about the
vehicle you have just repaired?
Something may be hidden!
22

23. Joining
Any joins made in an area such as
this will have damaged the
integrity of the material; it
will have been significantly
weakened.
If the technician is a competent
welder then the next stage is to
use manufacturers repair data.
Being able to weld does not mean
the welding will be carried out
correctly.
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24. Joining
Consider joining in these highlighted areas.
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25. Welding Faults
25

26. Welding Faults
Fast travel speed will likely be completed with a narrow stringy
looking bead and will have little or no penetration.
Full fusion will have not taken place.
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27. Welding Faults
Slow travel speed can be identified by a wide weld bead, large heat
effected area (band), excess penetration.
In some cases burn through may be evident within the bead length.
The steel could be damaged from overheating.
27

28. Welding Faults
Low voltage can have a similar impact to fast travel speed.
Poor fusion would of taken place resulting in narrow weld bead, and
lack of penetration.
Not acceptable as a suitable weld.
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29. Welding Faults
High voltage can lead to a flat weld bead, burn through, excessive
penetration and heat damage. Cratering within the weld bead may be
present.
Not acceptable as a suitable weld.
29

30. This image has areas of porosity and may be hard to spot.
Welding Faults
Porosity is a defect caused by incorrect gas flow, no gas, dirty work
piece and possible contaminates generated from dirty or corroded
welding wire.
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31. Welding Faults
Porosity can better be seen when the weld is x-rayed.
Notice the holes within the weld bead. This will significantly reduce
the integrity of the weld bead.
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32. Welding Faults
Porosity in some cases can be very easy to identify as this example
highlights. The top weld is good and the bottom weld contains a large
amount of porosity.
Not acceptable as a good weld.
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33. Poor penetration.
Welding Faults
No penetration Good
penetration
Excessive heat
33

34. Welding Faults
A range of completed welds which
are good but have slight
differences to each other.
These differences are a result of
slight changes to settings.
Settings can vary from individual
technicians. Sometimes this may
be due to the working speed of
the individual as some people may
weld slower or faster.
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35. Welding Faults
This weld bead has been completed with the correct travel speed,
voltage setting, bead width, bead height and the heat band is limited.
Penetration is likely to be good.
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36. Welding Faults
The effects of heat can be seen within this example of different
completed welds.
36

37. Welding Faults
No faults are evident here, the
difference is with the welding
equipment that was used or the
settings.
Manual pulsed and auto pulsed.
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38. Results of poor welding. Normally
something as bad as this can be
attributed to lack of competence
and skill level of the repair
technician.
Welding Faults
38

39. Welding Faults
This type of weld is normally used as a ‘tack’ weld. Tack welds will
hold panels in place to check for fit before final welding takes
place. A join made of these is weak.
Not acceptable as a good weld.
39

40. Welding Faults
Tack welds being applied to hold
a panel in place to check final
alignment before final welding
takes place.
40

41. Butt weld completed after final
checks for fitment.
Welding Faults
41

42. This type of weld is called a
plug weld and is not a fault as
such but becomes an inadequate
weld if used in the wrong place.
Normally used to fill holes left
from spot weld removal.
Used when no resistance spot
welder is available and can
damage materials such as high
strength steels.
Welding Faults
42

43. Welding Faults
Another example of plug welds having been used on a vehicle panel.
43

44. Welding Faults
Cracks within weld beads.
Can be more common when welding
aluminium and may be due to
different factors such as the
effects of heat, shrinkage or
incompatible materials. Cracks
will become larger over time and
may lead to joint failure.
Not acceptable.
44

45. A cross section of a crack visible from the use of a penetrant dye.
Welding Faults
45

46. Welding Faults
Resistance (spot) welding is
carried out to replicate the
original manufacturers
specification.
It also uses less heat than MAG
plug welding and therefore does
not damage the material.
However, as with MAG/MIG welding
it should be used in accordance
with manufacturers repair methods
because there will be areas that
it should not be used in.
46

47. Welding Faults
The technology used within
resistance welding machines has
changed greatly in the last 5
years alone. As with MIG/MAG
welding, equipment has had to
keep pace with the demands of the
vehicle repair industry.
Basic pincer type spot welding
machines such as this one should
no longer be used for welding on
vehicles.
This is because tip pressure can
not be measured, the welder can
not be set to recognise different
materials and the amperage falls
far short of what should be used.
47

48. The equipment is normally tested
and approved for use by
manufacturers for use within
their dealer networks.
Machines should be capable of:
Adjusting tip pressure
Recognising materials
Give indication of good and bad
welds
Be able to reach the required
power levels
Welding Faults
48

49. Spot Welding Machine Display
49
Gun type Material
Tip
pressure
Arm length Plate
No.
Material
thickness
Weld time
Power

50. Welding being carried out.
50
Welding Faults

51. 51
The heat band.
Welding Faults
HEAT BAND

52. The nugget size.
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Welding Faults
NUGGET

53. Welding Faults
Large heat bands
Very deep indentations
Material is likely to be damaged
Welds appear to be random
Excessive over use of resistance
welding:
53

54. This image highlights grinding
carried out to remove spot welds.
The heat generated could damage
the underlying panel.
Excessive grinding and its
effects:
Welding Faults
54

55. Welding Faults
Excessive grinding and its effects.
55

56. 56
Excessive grinding and its effects.
Welding Faults
Grinding that has been part finished.

57. 57
Excessive grinding and its effects.
Welding Faults
Grinding has been completed.

58. Over grinding.
This is the same panel after
sandblasting and you can see how
the metal has been thinned.
This will leave a very weak joint
even if holes are not evident.
Excessive grinding and its
effects:
Welding Faults
58

59. Welding Faults
59

60. Welding Faults
The welding of high strength steel should not be carried out.
Normally a new part such as a ‘B’ pillar will be supplied whole with
the inner and outer panels pre welded to protect the inner or
intermediate panel from heat generated through welding processes
within the workshop.
Normally these panels cannot be sectioned.
Sectioning, if any, should only be carried out following specific
manufacturer’s guidelines.
60

61. Time for some practical experience
We shall look at different welding situations.
We shall attempt to complete some welding on steel coupons.
We shall assess the different results of the welded coupons.
Outcome: To help recognise the different types of welding errors and
faults that may be encountered when carrying out vehicle inspections.
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62. Joining
Using the samples that you have created and the assessment sheet
provided.
1) Can you recognise any possible faults?
2) What are the results of the joints in terms of weld bead width,
penetration and the bead height?
3) What are the results of the destructive testing?
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63. THANK YOU
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