BMW X5: Welding And Soldering Steel Parts

IMPORTANT: Comply with the following topics from "Body, General": Safety regulations.

Handling electrical/electronic equipment, airbags and restraint systems.

A. Welding steel parts:

1. General information
   • The following procedures are used for repairs:
     • MAG welding (M etal A ctive G as welding)
     • Resistance pressure spot welding (referred to in the following and in the repair instructions as spot welding).
   • Take the number and location of weld spots and MAG weld seams from the separated part.

     Replace areas inaccessible to spot-welding tongs with MAG plug/spot welds at the same distance. Diameter of bores for plug/spot welds 8 mm.

   • In the case of emissions extraction, observe a minimum distance of 30 cm for MAG welding during the welding process. Otherwise the inert gas would be drawn off.
   • Follow the equipment manufacturer's instructions for use.
2. Work materials
   • MAG welding:
     • Steel welding apparatus (refer to WORKSHOP EQUIPMENT PLANNING CD, Chapter 7).
     • Steel welding wire - G3SI1 (SG2) or alternatively G4SI1 (SG3)
     • Welding mask
     • Gas bottle containing inert gas (82 % argon, 18 % CO 2)
   • Resistance pressure spot welding:
     • Spot-welding apparatus (refer to WORKSHOP EQUIPMENT PLANNING CD, Chapter 7).
     • Protective goggles
3. Preparations for MAG and spot-welding
   • Remove the paint coating in an area of approx. 30 mm around the weld seam or spot.
     • The zinc coating underneath must be removed during the MAG welding operation.
     • It is not necessary to remove the zinc coating underneath during spot-welding.
   • Remove the paint coating on the reverse side of the weld seam or spot.
     • Contaminants will otherwise enter the weld pool via the root of the weld seam.
     • An insufficient electron flow prevents an optimum spot-weld joint.
   • Coat all metal overlaps and weld spot flanges with welding primer.
   • To determine the optimum electrode contact force for spot-welding, carry out spot-weld shear tests on sample metal sheets.
   • In order to keep the electron flow short during MAG welding on the body, you must if possible attach the ground terminal directly to the component to be welded.
4. Welding
   • During MAG welding, the weld gap must be kept as small as possible. The larger the weld gap, the lower will be the strength of the joint.
   • During spot-welding, the metal flanges to be joined must be placed as close together as possible without gaps.

     The larger the gap, the lower will be the strength of the joint.

     Minimum gap between welding spots 25 mm.

5. Subsequent treatment of weld joints:
   • When grinding a weld seam, do not grind thin the base material next to the seam.
   • After joining, clean all weld seams and spots with a stainless steel wire brush.
   • Remove burnt paint with a stainless steel wire brush.
   • All weld joints sealed off with body sealing compound in original state must be primed and sealed off again thoroughly after repairing. Replace damaged or removed antinoise compounds.

B. Soldering steel parts:

1. General information
   • The following procedures are used for repairs:
     • Gas brazing
     • Tinning
   • The MIG soldering procedure is not used in repairs for strength reasons. MIG soldered/brazed seams used in series production are replaced in repairs by MAG weld seams.
   • Areas brazed in vehicle production are joined during repairs with the same procedure.
   • It is possible when straightening steel parts to correct irregularities smaller than 2 mm with filler.

     If in exceptional cases the irregularities are in excess of 2 mm, these areas must be tinned.

     Only visible areas of the outer skin and on the support carrier must be tinned.

     All areas which have covers on the vehicle are not to be tinned.

NOTE: Only applicable within the European Union!

European used-car regulations prohibit the use of tin containing lead in motor vehicles introduced after 01.07.2003!

2. Work materials
   • Gas brazing:
     • Tube pack and torch (gas torch)
     • Brazing solder
     • Gas bottles (oxygen and acetylene)
     • Welding goggles
   • Tinning:
     • Tube pack and torch (torch for tinning)
     • Tinning paste
     • Tin
     • Gas bottle (acetylene)
     • Protective goggles
3. Preparations for brazing/tinning
   • Heat brazed joints to be opened with an autogenous flame. Lift off remaining metal and remove remaining brazing solder with a wire brush.
   • Remove the paint and zinc coating in an area of approx. 30 mm around the seam to be soldered.
   • Remove the paint and zinc coating in the tin-plating area and approx. 30 mm beyond.
4. Brazing/tinning
   • Execute brazed seam without overheating the solder and with low heat dissipation. If necessary, use heat protecting paste.
5. Subsequent treatment of brazed joints:
   • Remove burnt residual zinc completely. Straighten, grind and tin visible connection points.
   • Remove burnt paint with a stainless steel wire brush.

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