General information
For simplicity, in the illustrations on the following pages, the type of weld is indicated only when it differs from that used in the production of the vehicle.
Welding seams used in repair work are indicated in the figures as follows:
- a Single or multiple spot welding
- b Solid inert gas weld
When carrying out welding work, the following rules must be observed.
- Where spot welding has been used in the manufacture of the bodywork, when replacing parts, spot welding should also be carried out if possible. In these repeated welding joints, the welding points must be spaced 30 mm apart.
- When performing spot welding, it is recommended that specimens of the same metal welded with the same equipment be subjected to delamination tests. These tests will make sure that the equipment used will provide quality welding. If it is not possible to perform spot welding, a cork weld should be performed.
- Electrodes used in manual spot welding with a welding gun should not be longer than 300 mm.
- Single-sided spot welding is not allowed.
- Hard soldering and gas welding are not allowed, EXCEPT when it was used in the manufacture of a car.
- When connecting three or more sheets of metal, inert gas plug welding should be used to ensure a strong connection.
- Plug welding in an inert gas should be used in cases where, due to difficulty of access, it is impossible to use a spot welding machine. When replacing the factory spot weld, it is necessary to drill or punch holes with a diameter of about 8 mm, after which the inert gas plug welding must be performed. The number of plug weld points must exactly match the number of factory weld points that have been drilled out.
- After the spot weld has been removed, each hole in the existing panel must be filled with the appropriate section of the plug weld in an inert gas.
Electronic control units
Vehicle-mounted electronic control units make it necessary to take precautions when performing welding repairs. Intense heat and vibration during welding can damage the electronic components.
In particular, certain precautions must be observed when removing or disconnecting the airbag control unit.
Equipment
Before starting any diagnostic procedure, make sure that all equipment is working properly and that all cables and connectors are in good condition. This applies in particular to electronic control units.
Seat belt buckles
Seat belt anchorages play an important role in vehicle safety. When carrying out repairs on these parts, it is important to follow all factory specifications. Please note that HSLA is used for the fastening parts of the seat belts.
Therefore, if possible, use the factory seat belts complete with locks and fasteners. Panel cuts should be made so as not to damage the fastening parts of the seat belts.
All welds within 250 mm of the seat belt attachment points must be carefully checked for strength, including areas between weld points.
Caution: Damaged body parts that contain seat belt attachment points MUST be replaced entirely with new ones, as the welds located at these locations affect safety and must not be broken.
High strength steels
Body panels are now often made from high strength steels to improve passive safety and reduce body weight. Because high strength steel panels cannot be visually identified during repair work and because they are more sensitive to increased heat than mild steel, it is recommended that the following work practices be followed at all times.
Although there are differences in the details of individual repairs, the following Body Panel Repair Rules have been developed to facilitate repairs and reduce the amount of work. If in the process of a particular type of body repair it is necessary to deviate from these Rules, the relevant information is included in the description of the technology for performing operations.
Elimination of deformations
If possible, the deformation of the structural elements of the body should be eliminated by mechanical action without heating the parts. Do not try to straighten the part in one go. Repeat the impacts, alternating them with the removal of mechanical force, and use these pauses to check the geometry of the part.
Body repair stand
Unless the repair involves decorative body panels, it should be carried out at a body repair bench to ensure that impact deformation does not extend to more distant elements of the body structure. Mounting the vehicle on a body repair stand ensures that the repair or replacement of individual panels does not cause additional distortion of the body geometry. If this method fails to restore the original geometry of the part, the damaged load-bearing body parts must be replaced. Damaged sections of panels should be cut with a high-speed saw, NOT with an oxy-acetylene torch. As a rule, all transverse dimensions of the body are symmetrical about the longitudinal axis of symmetry. Therefore, the initial diagnosis of body deformation should be carried out by diagonal measurements and an assessment of discrepancies in measurements.
Inspection
In every road traffic accident, various damages to the body occur. The organization of repair work is determined by the degree of damage to the body and the equipment that can be used for repair. Most damage to the body can be detected visually, which allows an approximate assessment of their severity. Sometimes the impact deformation extends beyond the immediate damaged area. The degree of deformation must be accurately determined so that, as a result of the repair, the load-bearing elements of the body return to their original shape. Initial diagnosis can be performed using a plumb bob and caliper. Accurate measurement of body deformations can be performed using special instruments. If during the repair it is necessary to replace the load-bearing elements of the body, it is recommended to use a body repair stand.
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