Coil Processing Equipment: Common Questions and Misconceptions

In today's competitive market, it has become critical for manufacturers and service centers to operate as efficiently as possible. Decisions made today regarding the operation of a company can have long term ramifications for years to come. As a result, the information by which these decisions are based must be up to date, accurate, and clearly defined.

In the area of coil processing, there are many common misconceptions which often influence this decision making process.

Left unchallenged, these misconceptions are perceived as fact and ultimately affect how Coil Processing Equipment is designed, configured, and operated. As a result, companies are often unknowingly penalized by design limitations that restrict overall productivity and increase initial purchase costs.

Many of these misconceptions date back to the very origin of coil processing while others evolved as new technology developed. Most misconceptions have a factual basis by which they were formed.

In some cases, the association of a problem and or limitation with a particular process or design continue long after technical developments have eliminated the problem. In other cases, the misinterpretation of information surrounding a basic concept of operation developed into a misconception.

Under close examination, many of these items can be easily clarified by reviewing the basic underlying principles of operation. By having an understanding of how a system operates as well as why it operates in a certain manner, companies are better prepared to make critical decision concerning their Coil Processing Systems.

The answers to frequently asked questions and the clarification of many common misconceptions are outlined here.

  • What Is The Difference Between A Cut‑To‑Length And A Blanking Line?

    Misconception: While there is a growing emphasis put on the use of blanks, there remains confusion in regards to the actual definition of a Cut‑To‑Length Line as opposed to a Blanking Line, and a blank as opposed to a sheet. Clarification: A blank is generally thought of as a relatively close tolerance part. Typically, it is already cut to a specific size. As a result, a blank normally goes directly into the next manufacturing process without being resheared. A sheet […]
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  • Is Aluminum Easier To Level Than Steel?

    Misconception: Aluminum normally takes less force to cut than steel. Consequently, it is common belief that it is easier to level as well. Clarification: In order to induce permanent set into a particular type of material, the material must be stretched beyond its yield. If yield is not exceeded, the material will spring back to its original shape. All steels have the same elasticity regardless of tensile or yield strength; that is, until the yield point is reached, they all […]
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  • Do Looping Type Lines Reintroduce Coil Set?

    Misconception: In some applications, looping type CTL/Blanking Lines can reintroduce set back into the strip after it has already been leveled. While this is a true statement, it is often perceived as an inherent problem associated with this particular type of line. Clarification: A looping type line operates with an accumulation loop located between the Leveler and Feed. The loop allows the material to be leveled continuously while the Feed stops it momentarily for shearing. Because the material is leveled […]
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  • What Is The Difference Between Machine Repeatability And Part Repeatability?

    Misconception: Although distinctly different, these specifications are often misinterpreted as having the same meaning. Clarification: Repeatability refers to the ability to repeat or duplicate a given set of conditions or circumstances within a specific range or tolerance. “Machine” repeatability refers to the ability of a particular machine to mechanically repeat a motion or action. As an example, in the case of a roll Feed, if the Feed reportedly has a machine repeatability of ±.005″ (0.127 mm) the machine would supposedly […]
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  • Do Pull‑Off Uncoilers Stretch Thin And/Or Soft Material?

    Misconception: It is sometimes suggested that pull‑off type Uncoilers will stretch thin and/or soft material during continuous line operation. Consequently, a powered payoff type Uncoiler should be used in these applications. Is there a factual basis to substantiate this claim? Clarification: Uncoiler are used in two basic modes of operation . A powered type Uncoiler is driven in order to produce a slack loop of uncoiled material between the Uncoiler and Leveler. This slack loop provides loose material to feed […]
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  • Do Fixed Edge Trimmers Eliminate Camber?

    Misconception: While Edge Trimmers are often used to trim a strip to a specific width prior to being cut‑to‑length, the process is often perceived as having the ability to eliminate camber as well. Clarification: Virtually all material has some degree of camber. There are two forms. The most predominate is dubbed “sweep”. Sweep refers to a strip in which the curvature of the material continues in the same direction throughout the coil. This would be representative for most mill coils. […]
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  • What Is The Best Location For An Edge Trimmer?

    Misconception: It is fairly common for some manufacturers to locate the Edge Trimmer before the Leveler while other manufacturers locate the unit directly after. Is there a reason for doing so? Clarification: With any slitting/shearing process, there is stress induced into the material as it is cut. Typically, the heavier the material and the narrower the strip, the greater the potential stress. By locating the Edge Trimmer before the Leveler, the strip is leveled after being trimmed thereby reducing this […]
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  • How is a Leveler’s configuration determined?

    Misconception: While leveler designs may vary from manufacturer to manufacturer, there are basic fundamentals that ultimately determine a leveler’s configuration for a specific application. Clarification: The most important consideration when selecting a leveler is work roll diameter and roll spacing. The diameter of these rolls will determine the gage range the machine can effectively level. As an example, a 1.75″ (44 mm) diameter roll would typically have an effective range of .024″ (.610 mm) through .134″ (3.4 mm) mild steel, […]
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  • What is camber?

    Misconception: While virtually everyone in manufacturing has been exposed to the problems caused by camber, uncertainty remains regarding how camber is defined and to what degree it influences part tolerances. Clarification: Camber is the deviation of a side edge of a strip from a straight edge. It is caused by one side of the strip being longer than the other. Camber is measured by placing a straight edge on the concave side of the strip and measuring the distance between […]
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  • Do Bow Tie Shears Produce Closer Tolerances Than Standard Rake Shears?

    Misconception: Because of their widespread use in Blanking Lines, the bow tie Shear is often perceived as being capable of producing better tolerances than standard rake Shears. Clarification: A Shear’s design in regards to the type of blade used has no direct bearing on the tolerances a particular line is capable of producing. The tolerances achieved are primarily a function of the type of Measuring System the line incorporates and how the material is presented to the Shear. A Shear […]
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  • Do Standard Rake Shears Bend The Material?

    Misconception: It is common belief that straight blade or standard rake Shears have a tendency to bend one corner of the sheet being cut. The use of a bow tie Shear has been associated with the solution to this problem. Clarification: When used in certain applications, standard rake Shears have been known to bend down one edge of the strip as it is being cut, while in other applications it does not. In order to understand what causes the problem, […]
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  • What is the best location for a Leveler?

    Misconception: It was once common practice for manufacturers to locate the Leveler after the Shear. However, today most manufacturers position the Leveler before the Shear. What is the reason for doing so and how does Leveler location affect the finished parts? Clarification: When Levelers first came into widespread use several decades ago, it was typically located after the Shear. While this position offers the simplest integration into the line, it also imposed certain limitations. Because parts were measured and cut-to-length […]
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  • Do I need a Straightener and a Leveler?

    Misconception: It is relatively common to see some lines incorporating both a Straightener and a Leveler while other systems use only a Leveler. What’s the difference? Clarification: The practice of using both a Straightener and a Leveler in the same line varies from manufacturer to manufacturer. Typically, if both machines are used, the manufacturer will contend that by using a Straightener to remove coil set prior to leveling, better flatness can be achieved. Manufacturers that use only the Leveler maintain […]
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  • What is the difference between a Straightener and a Leveler?

    Misconception: Although there has been widespread use of Straighteners and Levelers for decades, there remains a great deal of confusion regarding the proper application and capabilities of each machine. Clarification: Conventional Straighteners, sometimes referred to as Flatteners, incorporate a series of large diameter work rolls. Typically, between five and eleven rolls are used. As the material passes through the rolls, it is alternately bent from the tangent of one roll to the tangent of the next. As a result of […]
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  • Is Cut-To-Length Line speed the same as yield (output)?

    Misconception: Line speed is a specification often used to help determine the production capability of a line. Line speed refers to the speed of the material during normal line operation. However, line speed is often misinterpreted as system output or yield which actually refers to the amount of material processed in a given minute. Line speed and yield would be identical if you were evaluating a continuously operating processing line such as a Slitter. However, it is frequently misapplied to […]
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