Characteristics of Steel Sheet - Bending and Strength
1. Bending and Strength
While considering design and strength, automotive body panels are press-formed in various shapes. By giving a steel panel its own designed shape, strength is increased. By assembling that panel with other parts, body rigidity is enhanced.

Steel Sheet Bending:
Automotive body panels are press formed with sharp bent areas where higher strength is necessary. Those sharply bent areas are called a crowns and have the following categories:
<Low Crown>
The bend radius of the curve is great or the edge is very gently sloping.
<High Crown>
The bend radius is very small or the edge is very sharp.
<Combination Crown>
A low crown and high crown are combined on one panel.
<Reverse Crown>
An edge sharply curved inward toward the panel.
When repairing a damaged body or panel, smaller loads are required for a low crowned panel because it has a large radius. A high crowned panel for deep-draw has a small radius and requires a certain level of pulling force against the deformation area. A reverse crown is incorporated in a panel that has a sharp inward curvature. Because of this, the strength is so concentrated that repair becomes difficult.
Angle Bending:

Panel is bent at a right angle. This is mainly used for doors, fenders and some outer panels.
Channel Bending:

This steel sheet bending method has greater strength than angle bending. It is mainly used for under-body component parts such as stiffeners, rear frame, cross members or a floor frame.
Box Gutter:

Used for parts that require higher strength such as side sills, pillars, roof side rail, and front side frame.
Beading:

Used for large panels such as the floor and roof, where the grooves strengthen the entire panel.
Hemming:

Used to joint skin panels such as hood, door and trunk to an inner frame or panel. It is also used in the rear wheel arch area of some models.
Burring:

Used around the punched water drain holes in floor panels. The projected edge around the hole increases panel strength.