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The FA B R ICATO R | An FMA Publication

w w w. t h e f a b r i c a t o r. c o m | April 2006

By Matthew Wa t s o n

The initial objective in selectingcoil handling equipment is todetermine the type of systembest-suited to the application.

Requirements—such as prod u c t i o nrates (feed length versus strokes perminute), material finish and condi-tion, available shop floor space, tool-ing, material yield strength, partial-coil operation, and required change-over time—all play important roles inthe selection process.

Newcomers to metal fabricatingand forming might find such equip-ment decision-making complex, buttechnical advances in manufacturinghave contributed to the developmentof more competitively pricedmachines that are much more accu-rate and flexible than previous gener-ations. As a result, the search for coil

handling equipment falls into one oftwo categories: combination space-s a v e r-type systems and conventionalcoil handling systems comprising indi-vidual pieces of equipment.

I t ’s important to understand whatthe equipment does, so that you canchoose the right coil handling systemfor your application.

A Combination Look

A coil stock handling system performsthree basic functions: uncoiling,straightening, and feeding.

A compact, servo-driven, space-s a v e r-type system (Figure 1) com-bines the straightening and feedingfunctions into a single unit, removingthe need for a looping pit. A poweredreel or cradle may perform the uncoil-ing function.

The economy of the pull-throughs t r a i ghtening approach is a factor,

which makes it popular for manyuncomplicated coil handling applica-tions that require only enough coil setto be removed to get the material intothe tool. More complicated coil han-dling applications, however, may callfor a conventional processingapproach with equipment dedicated toeach process, such as straightening.

Stamping operations looking toreplace an older air feed and pull-through straightener setup will needonly one piece of equipment. The exist-ing powered payout—motorized stockreel or powered cradle—can continueto supply the new servo-feed/ pull-through straightener with material.

If you’re thinking about adding apull-through straightener to a servo-driven roll feed, keep in mind that theservo feed must have sufficient pullingpower and gripping force to positionthe material precisely to length at

Getting a handle on

coil handlingOne size doesn’t fit all when selecting coil handling equipment

required production rates while alsoproviding the power to straighten thematerial. To maintain sufficient sur-face area contact on the material toavoid slippage in the feed, a sacrificein speed and/or a reduction in theamount of straightening may berequired.

For jobs that require a higherdegree of straightening, servo-drivenstraightener/feeder combination sys-tems with either a motorized stockreel or coil cradle (Figure 2) probablymake the most sense. Ty p i c a l l y, thecombination equipment has entranceand exit feed rolls with a precisionstraightener mounted between them.The entrance feed rolls can be used tothread the material into the machine.After thread-up, the entrance feedrolls assist the exit feed rolls in accu-rately positioning the material.

With two sets of feed rolls, thestraightener/feeder provides twice asmuch grip force as setups with a sepa-rate servo feed and a pull-throughs t r a i g h t e n e r. In some applications notdependent on high-speed processingtimes, all the straightening rolls in thestraightener/feeder may be powered,reducing material slippage and ensur-ing an accurate part length.

For applications in which heavymaterial is handled, a cradle/straight-ener/feeder combination (Figure 3) isusually the machine of choice. Thesemachines allow thick, high-yieldmaterial to be supported on the coil’souter diameter, minimizing the risk oflosing control of the coil.

These machines are not designedfor surface-sensitive material becausethe coils are supported by large-diam-eter coil cradle rolls that will mark thematerial as it starts and stops. They

FIGURE 1

A servo feed with pull-through straight-ener is a cost-effective method of upgrad-ing a pressroom.

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The FA B R ICATO R | An FMA Publication

April 2006 | w w w. t h e f a b r i c a t o r. c o m

also are not designed for partial-coiloperation, as it is not safe to try andreband the coil within the cradle.

Servo feeds with pull-throughstraighteners and servo-drivenstraightener/feeder combination sys-tems can be used with progressivetooling. However, they should be fit-ted with a straightener roll releasealong with a feed roll release. Thisallows the pilots to register the materi-al and help ensure acceptable per-formance while running progressive-die tooling.

Limited space favors the combina-tion coil systems. No looping pits arerequired, and servo feeds with pull-through straighteners and servo-drivenstraightener/feeder combination sys-tems typically require approximatelyone-third the floor space of a conven-tional line. The cradle/straightener/feeder combination is the true spacem a n a g e r, requiring approximately halfthe floor space of a conventional sys-tem equipped with an independentservo feed and straightener.

A Conventional Look

Combination systems do not comparefavorably to conventional systems(Figure 4) when it comes to abruptstops. When material is stoppedbetween rolls in a combination sys-tem, particularly staggered rolls as in as t r a i g h t e n e r, a series of straight lines isapt to be imprinted across the surface.These imprints are called stop marks,set marks, or even witness marks, thelatter being used when the marksshow up prominently only after a sub-sequent process such as painting orplating “bears witness” to them.

In combination systems, the mate-rial stops in the straightener withevery feed stroke, risking the chanceof such marks throughout the coil run.The stop marks will correspond direct-ly to the roll spacing and feed length.Thus, when it comes to surface-sensi-tive materials or materials destined foran application requiring a critical fin-ish, a conventional system is the pre-ferred equipment.

A conventional servo-feed system,which requires an independent

FIGURE 3

A combination system incorporating a straightener and feeder with a cradle is asuitable choice for thick, high-yield material not destined for a surface-sensitivea p p l i c a t i o n .

FIGURE 4

A conventional coil handling sys-tem is more suitable for an application

involving surface-sensitive material or pro-gressive-die tooling.

FIGURE 5

A corrective leveler can be integrated into a conventional coil handling system toprovide parts with a great degree of flatness.

s t r a i g h t e n e r, is ideal for applicationsinvolving surface-sensitive material orprogressive-die tooling. A poweredstraightener is an independently driv-en, freestanding machine, normallycontrolled with an ultrasonic loopcontrol device that monitors thematerial in the loop area and regulatesthe output speed of the straighteneraccordingly for synchronization withrelated equipment. Powered straight-eners can be adjusted to minimizestopping or be equipped with a“creep” speed for nearly continuousrunning to prevent witness marks incritical-finish applications.

The top feed roll of the servo feedis easily lifted for pilot pin registrationby the press control. This roll lift alsoallows for proper material tracking byallowing the material to relax everytime the rolls are opened.

Conventional systems also offer alot of flexibility in specialty applica-tions. In zig-zag operations, the mate-rial needs room to swing in the loop-ing area as the servo feed shifts lateral-ly with every stroke of the press. In

coil-fed or transfer operations, theservo feed can detach from the pressand power travel out of the way toallow room to move in a die cart andallow the press to be blank-fed fortransfer operations.

Conventional systems meet theneeds of handling high-strength, low-alloy (HSLA) steel as well. In somefacilities where HSLA blanks are pro-duced to support transfer operations atother locations, companies are findingout that a straightener works the mate-rial only enough to remove coil set asthe blanks are cut. As the blanks sitover time, the coil set can reappearwithin the blanks. For these applica-tions, a conventional coil system sup-plied with a corrective leveler in placeof a straightener can provide the solu-tion. A corrective leveler with 17 or19 work rolls allows the material to beworked more substantially and pro-duces a part that is free from all mate-rial memory. A corrective leveler(Figure 5) also allows for shape cor-rection to reduce or remove edge waveand center buckle coil condit i o n s .

FIGURE 2

A combination coil handling system uses one-third the floor space of a conventionals y s t e m .

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The FA B R ICATO R | An FMA Publication

w w w. t h e f a b r i c a t o r. c o m | April 2006

Conventional coil handling sys-tems do carry higher price tags thancombination systems and take upmore floor space, but for high-prod u c-tion stamping where versatility andp r oduction are priorities, a conven-tional line with independent servofeed and independent straightenerreigns supreme.

A Look at Automation

Automation can be applied to bothcombination and conventional coilhandling systems. The level ofautomation desired needs to bedefined early in the selection process.

At first glance it appears thatautomation adds cost to the equip-ment. However, this automation can

quickly pay for itself in reduced down-time. Automation levels can rangefrom mild to wild. A “ m i l d ” a u t o m a-tion system today provides for com-munication between the coil handlingequipment and the press control. Am oderate level of automation coversequipment communication require-ments as well as push-button controls,

system diagnostics, programmablelogic control ladder logic, recom-m ended thread-up details, and mainte-nance information. A “ w i l d ” level ofautomation has not only all the fea-tures of the mild and moderate levels,but also complete system setup capabil-ities. In this “ w i l d ” scenario, a coil han-dling system can completely prepareitself for material thread-up following asimple download of a job order:

•The stock reel-powered backstopsets to the proper material width.

•The brake tension regulates asthe coil outside diameter is reduced.

•The straightener head sets up forthe material thickness.

•The straightener-powered edgeguides set to material width.

•The feed sets up for feed lengthand speed.

•Powered edge guides set to width.•The powered cabinet adjusts to

required passline height.With these upper levels of automa-

tion, the downtime associated withmaterial thread-up is significantlyr e d u c e d .

Before investing in coil handlingequipment and automation, look hardat your application, floor space require-ments, and material specifications.Those answers will help you get a han-dle on your coil handling decision.Matthew Watson is national sales manager,FORMTEK Maine, Cooper- We y m o u t h ,Peterson, Rowe, B&K, Coilmate/Dicker-man Divisions, 76 Hinckley Road, Clinton,ME 04927, 800-247-2645, ext. 200,w w w.cwpcoil.com, www. r u n w i t h r o w e . c o m .

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Want more information?• Conventional coil handling lines

a re best for processing surf a c e - s e n-

sitive materials. To learn more about

prefinished metals, check out

“ P refinishing trends toward gro w t h ”

at w w w. t h e f a b r i c a t o r. c o m / F i n i s h i n g /

F i n i s h i n g _ A rticle. cfm?ID=973.

• For a closer look at press feeds,

read “Press feed options for stam-

pers” at w w w.thefabricator.com/

P re s s F e e d i n g / P re s s F e e d i n g _ A rt i c l e .

c f m ? I D = 4 5 8.

• To see a video of a conventional

coil processing line, visit w w w. c w p

c o i l . c o m / C P S / c p s _ v i d e o . a s p.

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