Body
 The
body of an automobile is categorized according to the number of doors,
the arrangement of seats, and the roof structure. Their roofs are
conventionally supported by pillars on each side of the body in recent
times, there are convertible models with retractable fabric tops that
rely on the pillar at the side of the windshield for upper body
strength, as convertible mechanisms and glass areas are essentially
nonstructural. The glass areas have been increased for improved
visibility and for aesthetic reasons. New designs are usually programmed
on three- to six-year cycles with generally minor refinements appearing
during the cycle.
Redesigning was a tough job in the past, when as much as four years of
planning and new tool purchasing was needed for a completely new design.
Computer-aided design (CAD) and computer-aided manufacturing (CAM)
techniques may now be used to reduce this time requirement by 50 percent
or more.
Sheet steel is generally used to make automotive bodies. Elements are
added to the alloy to improve its ability to be formed into deeper
depressions without wrinkling or tearing in manufacturing presses. Steel
is used because of its general availability, low cost, and good
workability. Other materials for certain other materials are also used.
Other materials, such as aluminum, fiberglass, and carbon fiber
reinforced plastic are used because of their special properties.
For more toughness and resistance to brittle deformation, Polyamide,
polyester, polystyrene, polypropylene, and ethylene plastics have been
formulated. Tooling for plastic components generally costs less and
requires less time to develop than that for steel components.
Painting and priming processes are used to protect bodies from
corrosive elements and to maintain their strength and appearance. Bodies
are first dipped in cleaning baths to remove oil and other foreign
matter and then they go through a succession of dip and spray cycles.
Enamel and acrylic lacquer are both in common use.
Electrodeposition of the sprayed paint, a process in which the paint
spray is given an electrostatic charge and then attracted to the surface
by a high voltage, helps assure that an even coat is applied and that
hard-to-reach areas are covered. To speed up the drying process in the
factories, ovens with conveyer lines are used. In those body areas that
are more susceptible to corrode, galvanized steel with a protective zinc
coating and corrosion-resistant stainless steel are used.
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