2.3. Doors

As with the F01, the doors of the F10 are made of aluminum reinforced with sheet-metal intrusion beams.

Fig 1: Identifying F10 Front And Rear Doors

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Identifying F10 Intrusion Beams On Doors

Courtesy of BMW OF NORTH AMERICA, INC.

Large stamped sheet metal intrusion beams within the doors transfer force to the body and ensure high rigidity and component quality. The implementation of very deep stamping in the fabrication of the inner door panel structure and the clever use of a hinge reinforcement have enable a sophisticated design/contour of the exterior.

The window frame area fulfills the highest requirements for rigidity. It is a single section made of only two sheet-metal parts with minimum dimensions. Even in the visually sensitive window frame area, the intensive BMW exterior design queues where able to be implemented.

Advantages of this design are:

• Reduced CO₂ emissions and increased driving dynamics due to decreased weight (23 kg per vehicle lighter than a comparable steel version)
• Interior impression of an improved spaciousness.
• Allows more light into the passenger compartment
• Improved visibility
• Window frames look lighter and slimmer when the doors are closed
• When the doors are open, the window frames look solid with a high-quality appeal
• Maximum form stability of the separate components provided by one-piece inner door panels
• Lowest possible number of components for the door structure
• Laser welding and structural adhesive bonding as the joining technologies of the door structure.

BMW has already made frequent use of aluminum door structures in the past, e. g. for the E52, E63, E64. However, only since the F01 have aluminum doors been produced for vehicles in large quantities.

The development objective for the F10 door structure, therefore, was to implement the familiar concept for an aluminum door from the F01 as a door that can be manufactured even in larger quantities at acceptable costs.

However, aluminum is not as easy to shape as steel, so aluminum stamping parts are much more difficult to manufacture than their steel counterparts, particularly when the stamping depths are considerable.

With the development of a new structure concept (with large braces to transmit force), manufacturing feasibility was ensured without having to forego the proven metal plate component construction methods