Definitions
American Institute of Steel Construction (AISC): With headquarters in Chicago, AISC is a not-for-profit technical institute and trade association established in 1921 to serve the structural steel design community and construction industry. Chicago Metal Rolled Products is an active member of the Benders and Rollers Committee of AISC.
Buckling or crippling: the collapse of part of a section. For example, the web of a beam might collapse under the pressure of hard-way bending
Circular stairs: Stairs that turn right or left as a person walks up them.
Compound bends: bending in two planes, i.e. the section has a radius in the plan view and a radius in the elevation. A beam bent both the easy way and the hard way is bent in two planes. You should specify the orientation for each plane. You should also specify what section of the circle each view is
Distortion: any departure from specified dimensions, usually in reference to mill tolerances
Easy way: bending a section against the weak (y-y) axis. A rectangular bar bent the easy way into a circle would look like a belt.
Ferrous metals: metals that contain iron.
Hard way: bending a section against the strong (x-x) axis. A rectangular bar bent the hard way into a circle would look like a metal washer. With beam bending the hard way, the web usually has to be held in tension to avoid crippling.
Helical bends: Often wrongly called spirals (spirals have varying radii but are bent in one plane, like a hose coiled on the ground or a heating element on an electric kitchen range). True helixes are used to create a circular staircase and can also be bent into 3-dimensional elliptical shapes.
Non-ferrous metals: metals that do not contain an appreciable amount of iron.
Off-axis bending: when a member is not rolled on either of its two primary axes.
Oil canning: Irregular warpage of a section of steel
Ovality: with round tube bending and bending of pipes, the difference in dimensions of a circular form comparing the largest dimension A to the smallest outside dimension B divided by the nominal OD.
Pitch: the height of a helical coil expressed in rise over run terms, e.g. a common pitch for stairs is 7/12, i.e. a 7in vertical rise is matched with a 12in horizontal run.
Profile tolerance: the variance allowed between the actual arc of a section and the specified radius
Roll bending: The metal stock is fed into the roller bender, which is usually built in a three- or four-roll configuration, and the lower rollers push against the feed path to force the metal stock into a predetermined bend design. The machines are also called section benders or angle rolls.
Rotary draw bending: Used for tube bending and bending of pipes. The metal stock is supported against a mandrel and a rotating tool provides the bending action.
Section Modulus: The strength of structural metal stock as determined by the formula S + I/c, where I is the moment of inertia of the cross section about the neutral axis and c is the distance from the neutral axis to the outermost fibers. For example, Chicago Metal’s capacity for the bending of beams exceeds 1,000 cubic inches.
Shrinkage: The reduction of a section’s dimension as the result of the pressure of bending.
Spiral bends: Sections bent in one plane with an increasing or decreasing radius.
Three Dimensional Bending (3D bending): Think of a roller coaster where you might not have a discrete shape like a helix or cone, but which hits x,y,z points in space.
Tolerance: the allowed variance from specified dimensions.
Trim, waste, pick-up, tangent, grip, run-off, lead in and lead out: all these terms refer to the amount of extra material required in the bending process because it is sometimes difficult if not impossible to bend material to the very end of the material. Please consult with us regarding the required lengths. The waste can be reduced by grouping multiple pieces in longer lengths to be rolled. Chicago Metal Rolled Products can roll lengths up to 105 feet.
Waves: Distortion of a sinuous nature of a section that should be smooth.
