BMW i8 spyder and i3 models to have strong impact on EV market starting 2014
These EVs replace steel with carbon fiber bodies and parts which will lighten the load considerably. and strengthen the bodies.Though carbon fiber is more expensive than steel, it reduces manufacturing costs considerably and allows for extended battery life.It is expected that these models will create a strong demand for EVs not only for BMW ,but will influence other manufacturers in the production of carbon fiber EV models. There are several interesting articles on Google.
Even though the carbon-fiber material is still much more expensive than steel, differences in the overall bodymaking process yield cost savings that help to offset the cost. For starters, the i3 body structure uses just 130 carbon-fiber pieces, compared with about 400 for a steel body. The smaller number is partly explained by the ability of engineers to design very complex parts for the molding process that would not be feasible with the huge stamping presses and dies used to make steel parts. Often a single complex carbon part can replace four or five metal parts that would be welded together.
“We can produce an i3 in about 20 hours, versus about 40 hours for a 3 Series car and using just one-half the space needed for a steel body shop,” said Daniel Schaefer, who oversaw development of the i3 production process.
Another important element in the time savings is the use of exterior body panels with molded-in color, eliminating the traditional paint shop — one of the most costly sections of a car factory.
Carbon fiber’s superior strength properties let structural engineers do things differently. For example, the i3 doesn’t need the familiar B-pillar to support the middle of the roof; the structure is strong enough to meet crash safety standards without it. This can translate into aesthetic payoffs.
“Without the B-pillar we have a relatively open-feeling interior, and when you open the doors, you
will see some carbon fiber in the body sides,” says Benoit Jacob, who directed the car’s styling. “This is interesting to look at. We left it unpainted, with just a clear ...
BMW also makes its own carbon fiber at 1/2 the market price.