Mercedes-Benz Body & Equipment Guideline for Metris - BM 447, Version November 27, 2015.
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4.7 Threaded and welded connections
4 Planning of bodies
4.7.2 Welded connections
General
In order to maintain the high standard of welding
demanded by Daimler AG, the work must only be
carried out by appropriately qualified welders. For
high-quality weld seams, we recommend that you:
•
clean the area to be welded thoroughly
•
make several short welding beads rather than one
long bead
•
make symmetrical beads to limit shrinkage
•
avoid more than 3 welds at any one point
•
avoid welding in strain-hardened zones
•
offset spot welds and tack welds.
The battery must be disconnected before any welding
work is carried out and airbags, the airbag control unit,
airbag sensors and seat belts must be protected from
welding spatter or removed if necessary.
Parts of the floor and roof are laser-welded. The side-
wall cover is laser-soldered to the roof side cover.
Choice of welding method
The mechanical properties of weld seams depend on
selecting an adequate welding method and on the
geometry of the elements to be joined.
If overlapping sheets are to be welded, the choice of
welding method will depend on whether only one or
both sides of the workpiece is/are accessible:
Accessible
sides
1
Gas-shielded plug welding
2
Resistance spot welding
Resistance spot welding
Resistance spot welding is used for welding overlapping
parts which are accessible from both sides. Spot weld-
ing of more than two sheet layers must be avoided.
Distance between spot welds
To avoid shunt effects, the specified distances between
the spot welds must be maintained (d = 10e + 10 mm).
Ratio of sheet thickness to distance between spot
welds
d Distance between spot welds
e Sheet thickness
