O.S.M.

Designation for outside of metal. See outside of metal outer panel.

OBI

See open-back inclinable press.

offset

The distance along the strain coordinate between the initial portion of a stress-strain curve and a parallel line that intersects the stress-strain curve at a value of stress (commonly 0.2%) that is used as a measure of the yield strength.  Used for materials that have no obvious yield point.

offset yield strength

The stress at which the strain exceeds by a specified amount (the offset) an extension of the initial proportional portion of the stress-strain curve; expressed in force per unit area.

oil canning

The distortion of a flat or nearly flat surface by finger pressure and its reversion to normal. Same as canning.See elastic instabilities.

olsen ductility test

A cupping test in which a piece of sheet metal, restrained except at the center, is deformed by a standard steel ball until fracture occurs.  The height of the cup at the time of fracture is a measure of the ductility.

open (radius flat) hem

Also called as radius flat hem or loose hem. (See Figure O1). A flange that is folded back over upon itself with the edge of a mating part between the fold.  This fastens the mating parts together.

open-back inclinable press

An inclinable press in which the opening at the back between the uprights is usually slightly more than the left-to-right dimension of the I slide flange.  See also inclinable press.

orange peel

Texture of steel that appears like an orange, either from the steel mill or after forming.

oscillating die

A universal die which contains a cutoff type sub-die that pivots in a horizontal plane with each press stroke.  This allows the blanking of rectangular, triangular, or trapezoid shaped blanks of various angles and sizes.

outer panel thickness

Thickness of the outer panel.

outer ram (binder) load

“Maximum pressure, usually in tons on the binder surface” (Automotive Steel Partnership, 1991, p. 12).

outside of metal flange length

Distance of the outer panel from the trim edge to the outside of metal in the mating flange area. (See Figure O2)

outside of metal outer panel (OSM)

Side of panel that lays on the hem die. (See Figure O3)

overbending

Bending metal a greater amount than called for in the finished piece to allow for springback.

overcrown

(1) The term used to signify that the curvature of a surface is too high. (2) Used for the overbending of a curved surface to compensate for spring back.

overhanging press

A gap press in which the frame overhangs the bed.  See also C-frame press.  Also called overhanger.