Invisible security

Discretely “hidden” airbags in leather interiors
Metapor chuck 580x905mm with individually operated clamping areas on a grinding machine. The area to be machined is positioned on a slightly raised 3D outline. (PresseBox) (Bleckede, ) Airbags for drivers and front seat passengers nowadays belong to the standard equipment of new passenger cars. Pretty often ten or more airbags of different kinds are built into a vehicle, however few or all of them, should not be visible if possible. In order to correspond to constantly growing quality requirements as well as the aesthetic requirements of customers, airbag systems are constantly being developed which do not affect design of vehicle interiors with regard to ergonomics or functionality.
Particularly with high-quality leather interiors visual appearance is not to be impaired by seams or cover functions of the discharge points. The aim is to dispense with seams within the target break area but at the same time guarantee that if necessary the leather material tears in a defined place within a few milliseconds thereby enabling inflation of an airbag. Special manufacturing techniques for partial thinning of the discharge surfaces are necessary.
The usual machining method of undercutting using a CNC controlled unit, whereby an oscillating cut on the rear side of the leather is carried out, does not always conform to the requirements of the vehicle designers. Frequently indentations are visible on the surface.
BMW uses a leather grinding process, whereby the discharge areas are carefully thinned down, without leaving any recognizable traces that the leather surface covers an air bag. The art lies in achieving the necessary measure of thinning out. The leather has to be thin enough, to enable the inflation of the airbag, but only so thinly ground that the structure of the leather material is retained.
In order to position the leather sections accurately, damage-free and quickly during the grinding process, BMW uses specially manufactured vacuum chucks from Witte Bleckede. The chuck surface is a micro-porous material. These Metapor chucks are particularly suitable for precision machining of extremely thin-walled, soft and fine materials. Work pieces are sucked down over their full surface and absolutely flat. Due to the micro-porous surface, which does not have any drilled holes, damage or work piece deformation cannot occur.
The Metapor surface has a slightly raised 3D area, which lifts the area of material to be ground above the remaining clamping surface, avoiding any interfering edges.
The chucks with dimensions 580x905mm are divided into several individually operated clamping areas, so that machining of leather sections of both left-hand and right-hand drive cars is possible.
The extremely accurately machined vacuum chucks ensure exact and secure positioning in X, Y
and Z.


Witte Barskamp KG
Horndorfer Weg 26-28
D-21354 Bleckede
Maren Röding
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