Revision for college students who are studying on an Automotive Body Repair course. Welding standards applicable for those in the body repair trade.

1. WELDING PROCESS AND
STANDARDS

2.  Aluminium & its alloys are likely to
increase as a body building material as it
is one third of the weight of similar
strength steel
 It is less corrosive than ferrous materials
 Non magnetic and recyclable
 Can be MIG/TIG & Spot welded, Riveted
or bonded
 Grades currently used are BS:5000,6000 &
7000 Alloys

3.  Aluminium alloys stretch easier than steels &
there is a requirement that tools be kept
separate for their exclusive use to avoid
corrosion & contamination with steels
 Where contact between dissimilar metals are
to be made & to avoid Electrolysis barrier
sealants or (Drachomet) coated fasteners
must be used

4.  As the electric arc creates a weld pool that is
exposed to the atmosphere there is danger of
attack from Oxygen, Nitrogen & Water
vapour
 These atmospheric conditions affect the
depth of penetration, influence the
character of the arc & also control weld
Spatter

5.  MIG (metal inert gas); inert gas is only
suitable for high alloy steels & aluminium
& not for thin sheet steel
 MAG (metal active gas) ideal for most car
body panels & low alloy steels
 Argon-mixtures are the most common
shielding gases offering the coldest arc,
minimum spatter & greatest tolerances
 As CO2 contents rises, so does spatter &
the arc is therefore more unstable &
difficult to control

6.  MAG Welding: 90% Argon, 5% Oxygen, 5% CO2.
 MIG Brazing: 70% Argon, 2% Oxygen, 5% CO2.
 Stainless Steel: 93% Argon, 2% Oxygen, 5% CO2.
 Aluminium: requires 2% Oxygen added to
promote the required initial flow

7.  ARGON: Reduces splashing in the weld
pool
 Carbon Dioxide: Allows the formation of
large droplets and reduces porosity
 Oxygen: Lowers surface tension & makes
the weld pool more liquid
 Hydrogen: Lessens oxidation
 Nitrogen dioxide: prevents ozone
formation

8. B.S. 1140: is the industry Standard for Resistance welding
B.S. 4872-1: is the Standard for M.I.G. MAG Welding (Steel)
B.S. 4872-2: is the Standard for T.I.G /M.I.G.Welding (Aluminium & Alloys)

9. Is the specification for the
approval & testing of Body
Repairers in Fusion welding

10.  Welds must be of a neat appearance.
 The root must be fully fused along the entire length of the weld.
 The profile of the cap should blend in smoothly with the parent
material
 The weld should be significantly free from imperfections.
 HOW IS THE WELD TESTED ?
 Penetration defects and lack of fusion can often be easily
detected by sectioning the welded area.
 An application of ‘acid’ to the sectioned welded joint followed by
bending the material in a press can identify defective welds .

11. Welding personnel are tested using metals of;
 1,0mm thickness
 2,0mm thickness
 HOW IS THE WELD TESTED
 Visual Inspection of weld
 Sheer/peel test