Roll Forming Glossary/Dictionary A-C

To help site visitors understand the roll forming, corrugating, and metal fabricating processes, Corrugated Metals, Inc. has included this one-of-a-kind glossary.

The glossary is organized as an alpha listing to quickly assist you in finding the term you are looking for.

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A device which stores materials in a defined amount so a new coil
can be installed and then welded to the old coil ensuring a non-interrupted material flow to the roll forming machine.

Angular tolerance

An angular tolerance of ±1° are typical in the roll forming
process. See tolerance types.


Stands for American Society for Testing and Materials.

Auxiliary operations

Operations outside the main roll forming process such as prepunching,
embossing, curving and coiling, and cutoff. See embossing, pre-notch/pre-punch press, and pre-notching.

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B-Deck is currently the most popular and widely used panel for decking. Type B-Deck or Wide Rib is frequently used for several applications such as flooring, siding, and roofing. The two main types of roof deck are B-Deck (HSB-36) or N-Deck (N-24). B-Deck is the most common type of roof deck and is typically used when spans are less than 10 feet. N-Deck is more commonly used in longer spans such as  8 feet to 16 feet.

Bend radius

The inside radius of a formed feature. The bend radius should be
equal to, or greater than, the material thickness. A small bend radius
can create fracturing at the bend due to the natural thinning that
does occur at the bend radius. Also called inside radius.

Bend radius - illustration


Changing the shape of metal sheet using successive pairs of forming
rollers. Bending does not change the thickness of the metal except
at the bend radius where a slight thinning occurs. Generally applied
to forming it is the creation of a formed feature by angular displacement
of a sheet metal workpiece.

Blanking press

A blanking press is punch press used in a multi-step forming process.
The blanking press forms a rough shape which then is subjected to
one or more secondary forming processes to produce a finished component.

Blind corners

A blind corner is a bend in a roll formed piece that cannot be
handled by direct roll contact.

Blind corners - illustration


Bow is the variation from a straight line in the vertical plane of
a roll formed piece. It can be either cross bow or longitudinal bow.
See camber, curve, and twist.

Bow - illustration

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Camber is the variation of a side edge from a straight line, the
gradual deviation from straightness of the edge of sheet or coil stock
caused during the slitting operation. Camber is the edgewise curvature, a lateral departure of a side edge of sheet or strip metal from a straight line.

Extreme camber contributes to curve, bow, and/or twist in the finished
part. See curve, bow, and twist.

Camber - illustration

Changeover time

The time it takes to change tooling. Long changeover times are costly
due to lost productivity.


A length of steel wound into roll-form.

Coil breaks or crossbreak

Coil breaks are a defective condition composed of ridges or marks
across the width of sheet or coil caused by improper coiling or leveling.
Creases or ridges which appear as parallel lines, transverse to the direction of rolling, and which generally extend across the width of the sheet. A discontinuous curvature in the strip in the direction in which the material was rolled or uncoiled. Coil breaks are generally found in uncoiled hot rolled strip.

Coil Set

A lengthwise curve or set found in coiled strip metals following its coil pattern. A departure from longitudinal flatness. It can be removed by roller or stretcher leveling from metals in the softer temper ranges.


Coiling is the process of winding flat material while it is still hot as it exists the extrusion rollers at the mill immediately after it has been formed.


Sheet metal rolled from slab or ingot that has been wound into coiled roll. Coils are considered the most efficient way to store and transport sheet metal. Master coils are produced at the mill and slit coils are converted from the master coils in narrower widths through the
slitting process. See sheet.

Cold reduction mill

Sheet and strip are cold reduced to the desired thickness for the
following reasons:

  1. To obtain the desired surface.
  2. To impart desired mechanical properties.
  3. To make gauges lighter than the hot strip mill can produce economically.
  4. To produce sheet and strip of more uniform thickness.

Cold rolled base

Coils that are cold worked or reduced to gauge on the tandem mill.

Cold rolled sheet

A product manufactured from hot rolled, descaled (pickled), coils by cold reducing to the desired thickness, generally followed by annealing and temper rolling. If the sheet is not annealed after cold reduction, it is known as full hard.

Cold rolling

Term applied to the operation of passing unheated metal through rolls
for the purpose of reducing its gauge.

Cold rolling mill

A mill that reduces the cross sectional area of the metal by rolling at approximately room temperature.

Cold strip mill

A mill that rolls strip without first reheating.

Cold work

Plastic deformation at such temperatures and rates that substantial
increases occur in the strength and hardness of the metal visible structural changes include changes in grain shape and, in some instances, mechanical twinning or banding.

Commercial tolerance

A range by which a product’s specifications can deviate from those
ordered and still meet the industry accepted ranges (defined in ASTM
Standards, etc.)

Conventional or standard roll
forming machines

Conventional or standard roll forming machines are more adaptable
than the single-duty machines which allows the roll tooling to be used with other profiles to make it more able to handle a variety of production needs. See single-duty machines.

Corrugated metal

Metallic coated sheet steel formed to a finished shape by passing the metal sheet through an engineered set of rollers by a metal fabricator. See corrugated metal revetment, roll forming.

Corrugated metal revetment

A military barricade designed to provide shelter or protection for humans and critical infrastructure assets against low angle high velocity fragments, shrapnel, and improvised explosive devices while offering protection as an anti-ram vehicle barrier. A corrugated metal revetment is made from some type of roll formed metal, typically heavy-gauge steel (16-gauge or 18-gauge). The corrugated metal revetment is also referred to as a bin revetment as is normally filled with sand or dirt.


The process of forming or ribbing a flat sheet of material into a consistent, symmetrical profile to increase that material’s strength to weight ratio up to 30% over the conventional material. The forming of sheet metal into a series of straight, parallel alternate ridges and grooves with a rolling mill equipped with matched roller dies or a press brake equipped with specially shaped punch and die.


Transverse ripples caused by a variation in strip shape during hot or cold reduction.

Cross section depth

The distance between the peak and valley of a corrugation.

Curve (also referred to as Sweep)

Curve is the variation from a straight line in the horizontal plane measured after the part has been roll formed. Causes of curve included incorrect horizontal roll alignment and uneven forming pressure. See
bow, camber, sweep, and twist.

Curve - illustration


Curving is the process of adding curvature to a flat sheet by passing it through a set of rollers using multiple passes to gradually add curvature, radial bending, without kinking or creasing the sheet. Curing adds strength and functionality to a flat sheet.


Process to uncoil sections of flat-rolled steel and cut them into a desired length. Cut-to-length product is normally shipped flat-stacked.

Cutoff machine

Mechanical or hydraulic equipment in the corrugating line which shears the material to length immediately following corrugation.

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