Laser welding
Audi has introduced laser welding for the production of the Audi A4.
The laser welding technique employs a high-energy light beam directed onto the weld by means of optical lenses or fiber optics.
During the welding process, the upper panel is welded onto the partially melted lower panel, creating a weld joint with no additional material.
When performing repairs, laser weld seams are replaced by SG welds or pop rivets.
Scheme 10
A - C-pillar laser-welded to inner side panel
4 x SG continuous seam in place of laser weld
B - Roof laser-welded to outer roof frame
Roof is repaired using SG plug weld seam in place of laser weld.
Scheme 11
C - Inner A-pillar to inner side panel
5 x SG plug weld seam in place of laser weld
D - Inner B-pillar to inner sill
10 x SG plug weld seam in place of laser weld
E - Lock reinforcement to inner side panel
4 x SG plug weld seam in place of laser weld
Scheme 12
In the case of the bonded joints, the joint between the sheet metal parts is formed only by the adhesive.
Scheme 13
In spot welded bonded joints, an electrically conductive adhesive is used between the panels, which allows problem free penetration for spot welding.
The welding current must not be increased during spot-weld bonding. The pre-press time must be extended to about 30 - 50 seconds because of the displacement of the adhesive. The emitted fumes must be extracted.
Spot-weld bonding is not performed in the service department.