| Mercedes-Benz is using lasers
to cut weight from its cars, improving safety and quality at the same
time.
The cumulative affect of such small weight savings will become more valuable
as OEMs, especially those making large luxury vehicles, strive to reduce
CO2 emissions.
Engineers used laser welding to join the doors on the new C-Class. Less
material is required to make the joint as a result – Mercedes estimates
it saves up to 250g per door. Joint strength is also higher and the door
frames are more slender, improving visibility.
“We were able to shorten the flange width from 16mm to 8mm,”
said Mercedes. “The geometry of the laser weld seams is narrower
than spot weld points, with higher crash and fatigue performance.”
Laser welding requires more precise positioning of components in the fixture
because small gaps are required to allow de-gassing of pre-coated steels.
As with all welding techniques, high strength steels are more challenging
to join than conventional steel grades.
“Laser welding of the high strength steel required a development
of new process parameters,” said Mercedes.
Laser welding is also used to fabricate the tail panel but for body-in-white
applications laser brazing is preferred because of improved joint aesthetics.
The bootlid and tailgate of the
C-Class are joined this way.
© Automotive Engineer, 2007 |
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