Roll Forming Handbook / Edited by George T. Halmos
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FIGURE 8.42 Foam-filled products picked up and moved with vacuum cups. (Courtesy of Metform International
Ltd.)
FIGURE 8.43 “Pick-and-place”unit rotates 908 and stacks roll-formed products. (Courtesy of CompuRoll Inc.)
Roll Forming Handbook8 -28
forward. The product can also be moved by magnetic rolls located aboveit. The suspended product will
be movedinto position then dropped either by demagnetizing the rollsorbypushing the productaway
from the rolls.
Finished products can be lifted up and movedsidewaysbyanoverhead vacuum (or magnet) “pick-up”
unit (Figure8.42 ). Robots can also be used to remove the finished products (Figure8.43). The higher
priced robot can only be justified if its speed matches the rate of production or if the finished products
havetobeplaced in various predetermined locations.
It is difficult to make astable bundle from nonnestable products. Products with 908 lips, “U” and “C”
channels, or nonnestable panels can be better nested if everysecond product is turned 1808 (flipped
over). Bundles with everysecond product turned over are shown in Figure8.44.Mechanical devices are
available for this type of material handling,but they are relatively expensive. Turning over everysecond
product may also reduce line speed. Therefore, wherever possible, the product designer should aim for
products that can be nested.
8.9.2 Separating and Protecting Finished Products
Most roll formed products can be handled without taking special precautions; others such as stainless
steel or aluminum with highgloss finish and some coated products havetobecarefully handled and
separated from each other.
After forming,assembling, and adding additional components, some rollformed products such as
garden sheds, metal fences, baseboardheaters, sidings, and trims for the automotive aftermarket are
placed directly into cardboard or other boxes, and sealed in the production line. The end user will receive
the products in the same boxes.
FIGURE 8.44 Piling nonnestable products by turning everysecond one over.
FIGURE 8.45 Corner protectors can prevent edge damage caused by strapping.
Coil Processing, Material Handling, and Plant Layout 8 -29
Other products sensitivetoscratchesare
shipped in bundles, separated by paper,plastic
or other soft materials. For manyyears after the
introduc tion of precoated coils, roll formed
prepainted products wereseparated fromeach
other by interleaving with paper,polyethylene or
other materials at the exit table. Interleafing is
expensiveand frequently the speed of the roll
forming line had to be reduced. Improvements in
the precoating systems and in the design of the
product haveeliminated most of the interleaving
requirement for building sheets. However,there
are still roll formed products for which inter-
leafing is required for handling and shipping.
8.9.2.1 Strapping and Crating Finished
Products
Several hundreds of pieces can be formed from
each coil. To reducehandling time and protect
the finished goods, the products are grouped
together,handled, store d, andshipped in
bundles, crates, boxes, or other shipping units.
Bundling,crating,and packaging are expensive
but necessar y. Failuretoprovid eenoug h
protection could lead to substantial damages,
complaints, and expensivereplacements. On the
otherhan d, over protectioncould be too
expensiveand makethe product noncompeti-
tive. Abalancehas to be maintained. If products
are toofrequently damaged, then they are
underprotected, but if thereisnever acomplaint, then most probably the companyspends too
much for “overprotecting” the goods.
One of the simplest methods for bundling goods is to use two or more straps. Steel is the most frequently
used strapping material. Plastic straps can be used for cardboardboxes or in cases when the straps are not
exposed to sharp edges of the product. Strapping can be applied manually or automatically.Inboth cases, it
is critical to apply proper strapping tension. If the bundle is loose, then the products slide out. If the strap is
too tight, then the edges of the product can be damaged. To preventedge damage, corner protectors are
frequently used (see Figure8.45).
8.9.2.2 Crating
To provide space for the forks of the forklift trucks
or other equipment, the strapped bundles haveto
be separated from each other.The most frequently
used separator is wood, usually low quality2£ 4s.
The wood can be strapped to the bundles
(Figure8.46)toprovide additional protection
and to avoid the manual handling of individual
pieces between bundles. Thereare endless
variations of protection, from strapping pieces
of wood to the bundles to elaborate, completely
enclosed wooden crates.
FIGURE 8.46 Wood protectors/separators strapped to
bundles.
FIGURE 8.47 Misplaced supportinpiled bundles can
damage the products.
Roll Forming Handbook8 -30
When bundles are stockedontop of each other,itisimportantthat the wood components supporting
the load should be on top of each other.Misplaced suppor ts can damage the bundles underneath them
(Figure8.47).
8.9.2.3 Boxes, Containers and Cradles
Avarietyofmetal, wire,paper,plastic, and other containers are used by the industrytostoreand ship roll
formed goods. The packaging material is dictated by price, type of product, storage, material handling,
and shipping requirements, indoor or outdoor application, and temporaryorfinal nature.
8.10 Finished Product Storage
The formed products maybestored for the next operation or for shipping.The storage can be within the
plant building or outdoors.
8.10.1 In-Plant Storage
Most of the roll formed goods are stored inside the plant. To save valuable plant floor area, bundles or
other products storage devices are stacked on top of each other,ashighaspracticalityand safetypermit.
8.10.1.1 Multiple Height Storage
Bundles, crates, tote boxes, cardboardboxes, and so on, can be piled on top of each other.The height of
piling is restricted by the crush resistance of the bottom unit in the pile, the stabilityofthe pile, the
maximum reach of the truck or crane, the height of the building, and the frequency of need to remove
packages from the middle or bottom of the pile. If bundle dividers or the bundle (package) lifting unit has
to be manually positioned, then the safe reaching or climbing height can be arestrictingfactor.
8.10.1.2 Storage Racks
Storage racks are frequently used when quick access to anyofthe loads is required. This method is
favoredtostoreunitized pallets, tote boxes, and goods sensitive to piling and damage. Products stored in
storage racks can occupy considerably morespace than goods piled on top of each other.The distance
between the storage rack columns also limits the length of products stored in racks.
8.10.1.3 Cantilever Racks
Cantilever racks are relatively expensive, but are occasionally used for storing long products such as
building panels, if quick access to anypackage and good protection are important.
One shortcoming of all rack storage system is that occasionally packages are left and “forgotten”at
higher storage levels.
8.10.2 Outdoor Storage
Building products, culvertpipes, and some other products can be stored outdoors. The biggest advantage
of outdoor storage is its low cost. Its disadvantages are that, in most cases, extra precaution has to be
taken against corrosion, pilfering,and loading and unloading in bad weather maynot be convenient.
Nestable products and dense piles must also be stored at aslight angle to drain water.The water may
originate from lubricant left on the product, rain, melting snow, or condensation. Products stored
outdoors cool down during the night. During the day,the densely piled metal acts as a“heatsink,”and the
water from the hot humid air condenses on the surface of the products. Excessive water can stain
prepainted, stainless steel, or aluminum sheets and can create white and eventually brown rust on
galvanized products. Unprotected “black” steel rusts so quickly that usually it is recommended that they
are not stored outdoors.
In ahumid sunnysummer week without anyrainfall, asingle crate of building products, wrapped
tightly in polyethylene sheet may generate 2to4gal (8 to 16 l) of water inside of the package. Therefore,
this method of protection should not be used.
Coil Processing, Material Handling, and Plant Layout 8 -31
8.10.3 Marking, Counting, and Weighing
Everybundle, and often everypiece, must be identified by some kind of amarking.
8.10.3.1 Product Marking
In manyinstances, each piecemust haveaproduct and manufacturer’sidentification. The marking can
be embossed in the manufacturing line by arotary embosser,bystamping in the cutoffpress, or by a
separate device.
Asimple wayofmarking the finished product is by handwriting.Although it is time consuming,the
operator often has time to do it while waiting for the next product. In addition to the occasional
illegibility, using an incorrect marking pen can cause the biggest problem. Inks that are not “weather-
and sunproof ”fade away .Opening the illegibly marked bundles to measure, remark and rebundle them
again can take 5to10times longer than it originally took to manufacture, mark, and bundle the
product.
Ink stamping is simple and inexpensive;itcan be done manually or by rolls. Labels can also be applied
manually or automatically.Labels are more expensivebut they can be colorful and contain more
information. One common problem with labels is that if aplant runs out of label stock, the complete
production line mayhavetobestopped.
Barcoded marking is gaining popularit ywith manufacturers of roll formed products. Manycomputer
programs used in the plant generate the barcoded tags or labels.
Nonweatherproof ink used withrubber stamps or on labels can also fade away.Incorrect adhesive or
label material creates additional problems.
Cardboard boxesare usually preprinted withproduct descriptions and advertisements. Bundles
and crates may be marked with felt pens, stenciled, or moreand morefrequently withbar-coded
labels.
Most marking problems are caused by human errors. Mismarking products can wreakhavoc;
therefore, education of employees is important.
8.10.3.2 Counting
To supply the right quantityofproductisabasic requirementinany business. The number of pieces
going into apackage can be countedmanually or by counters at the production line.
To minimize complaints, manufacturers occasionally supply afew “extra”pieces when shipping goods
for larger jobs at distant locations, such as construction sites. In other cases, operators tend to placea
scrap “protective” pieceunderneath or on top of the bundle to protect the goods. This well-intentioned
gesture may backfire unless these extra pieces are well marked. It can happen that customers return the
extra or scrap “protective” pieces for credit.
8.10.3.3 Weighing
The starting material for most roll formed products is purchased by length or weight. Products are
usually sold by other units, such as number of pieces or linear or areameasurements. If roll formed
products are sold by weight, it is importantthat the plant use ascale accurate enoughtomeet legal
requirements.
8.10.4 Truck Loading
Finished rollformed products occupy considerably morespacethan the coils(Figure8.48). They require
extra protection and careful handling.Therefore, the method of loading outgoing shipments is an
important partofplant layout and equipment selection. Most products are shipped by trucks. Railway
cars and containers are seldom used.
The method for loading trucks depends on the:
*
Type of product
*
Method of packaging
Roll Forming Handbook8 -32
*
Sensitivityofproduct to transportation
*
Loading facilities
*
Unloading facilities at the receiving end
*
Protection requirements during transportation
*
Weather conditions
*
Weight, length, and width restrictions
*
Safetyrequirements
*
Other specifications (e.g., exportshipment, protection against pilferage, etc.)
8.10.4.1 Type of Trucks
8.10.4.1.1 Closed Van
Closed vans are used if good protectionagainst weather is required or when open bed trucks are not
available. Loading,unloading,and access to products behind the last load in the van are restricted.
Vans are usually loaded (and unloaded) with low mast trucks or other rolling-lifting equipment that
can enter the vans. Therefore, “dock-level” loading (bed of the van in levelwith the shipping areafloor,as
shown in Figure8.49)isrequired at both the shipping and receiving ends.
Special vans, which handle standardsize pallets or skids, may be equipped with floor conveyors. These
conveyors supportthe load only during loading and unloading,and they eliminate the need for material
handling equipment entering the van.
8.10.4.1.2 Open Bed Trucks and Trailers
Open bed trucks and trailers are loaded by
cranes,trucks, or othermaterialhandling
equipment. Products are accessible along the
full length of the truck (trailer) bed. However,it
takes moretime to removeand install sides and
cover(tarpaulin) if such extra protection is
required. Abig advantage of the trailers, in
FIGURE 8.48 Finished products occupy 2to50times more space than coils.
FIGURE 8.49 Dock-level loading of truck.
Coil Processing, Material Handling, and Plant Layout 8 -33
addition to their size and large capacity,isthat they can be “dropped”atboth loading and unloading
points while the cab is hauling other trailers.
Open bed trucks and trailers can be loaded and unloaded by cranes or trucks both indoors and
outdoors. Some special trucks are equipped with self-loading/unloading cranes. This feature can be
useful at job sites or other locations where material handling equipment is not readily available.
Dock-levelloading of open bed trucks and trailers is also feasible. The advantage of dock-level loading
is easy access to the truck bed for the material handling personnel. The disadvantage of the arrangement
is the existence of large pits if they are inside the plant.
8.10.4.2 Truck Routes Inside and Outside of the Plant
Insufficient truck loading/unloading locations and facilities create delays, as well as production and
shipping problems. Excess facilities requireexcessive investment and result in unnecessaryspace.
Vans are usually parked outside the building backing to atruck door for level loading/unloading.
Sufficient yard space must be provided for maneuvering truck back and forth from the road to the
doors.
In-plant loading of open bed trucks and trailers can be arranged by backing into the building or
driving throughit. Drive-through is faster and safer but requires morespace. In-plant loading provides
weather protection. It is important to provide adequate drainage around the truck loading areas.
Rainwater or melting snow should be drained to avoid water running into the storage areas.
8.10.5 Railway Cars
In the case of long,heavy,orhighly piled products, it can be an advantage to ship them in railwaycars.
When using gondola cars, loading must be at floor level. Flatbed railwaycars can be loaded by crane, but
easy access to the cars must be provided. If railwayaccess is fromone direction only,then time-
consuming shunting is required. If adrive-througharrangement is feasible, then moving the “train”in
one direction is easier to arrange. In the case of long trains, protection (closing doors) is more
complicated. Shipping rollformed productbyrail is less and less frequently used.
8.10.6 Containers
Container shipments are occasionally required for overseas exportand other special cases.
8.11 Material Handling Equipment
8.11.1 Forklift Trucks and Side Loaders
Forklift trucks are frequently used material handling equipment when:
*
Volume is low
*
Products are handled in tote boxes
*
Capital funds are restricted or only aforklift truck is available
*
Building is not designed for acrane
*
Installation of extra supportand foundation for crane rails is not practical
*
The ceiling of building is too low
*
The building is rented or the operation is temporary
*
Boxcars or closed vans are used for transporting coils
*
Coils havetobemoved from one baytoanother
Roll Forming Handbook8 -34
The greatest advantage of the forklift trucks is their lowcost and versatility. The disadvantages are the
relatively large plant areatakenfor truck isles and large spaces needed for turning and maneuvering.In
some plants, coilscannot be loaded by forklift truck directly into the line.
Standardforks are used to movecoils on pallets or skids, especially with vertical axes. Occasionally,
forks are inserted into the horizontal coreorare at the outside of the coil. The concentrated forces at the
edges of the forks maydamage several laps of some thinner,softer,orsensitivetypeofmaterial.
Special “bull noses”(see Figure8.50)and other attachments are available to minimize the damage
to the inner core, but they are not suitable for loading coils directly onto uncoilers. Forklift trucks can
be used for handling relatively shortfinished products in tote boxesorpallets, but they are not
suitable to movelong products, such as building panels. Side loaders are similar to the forklift trucks
but the forks are at the side. They can move sideways, pick up the load, and then travelinthe
longitudinal direction. Because of this maneuverability, they can handle long loads but still require
wide isles and very large turning space. Therefore side loaders are usually not the best choose for
handling roll formed products.
8.11.2 Cranes
Coils or stacks of sheets are handled with the following types of cranes:
1. Overhead
2. Stacker
3. Jib
4. Gantry
5. Monorail
FIGURE 8.50 Forklift truck with “bull-nose.”
Coil Processing, Material Handling, and Plant Layout 8 -35
8.11.2.1 Overhead Cranes
Overhead cranes, such as shown in Figure 8.51 are the most frequently used and the most efficient
handling equipment for lifting and transporting material through the plant from receiving to shipping.
An overheadcrane does notoccupyvaluablefloorspace,itisversatile,and it canhandlecoils or sheets.It
canbeusedtounloadincomingmaterialfromopenbed trucks or railwaycars, move material into or from
storage, load roll forminglines,and handle finishedproducts.
One well-chosen crane can serve all the coil receiving,coil storage areas and up to 8to12roll forming
lines, depending on:
1. Coil sizes
2. Coil upending and weighing requirements
3. Distancetobetraveled from point of unloading to coil storage, and from coil storage to
equipment
4. Method of coil storage and layout
5. Availability of in-line storage and loading facilities
6. Frequency of removing partially used coils
7. Speed of roll forming line
8. Time spendto“digout”coils
9. Availability of proper below-hook attachments
10.Efficiency of craneoperator
When selecting acrane, the primaryconsideration should be its abilitytoperform its function in the
most economical way. Abreakdown of the coil handling crane can stop the production of all roll forming
lines and other operation in the plant.
FIGURE 8.51 Overhead cranehandling coilswithtelescopiccoilgrab. (Courtesy of DemagCranes&Components.)
Roll Forming Handbook8 -36
The span of the crane is usually determined by the building.The lifting capacity to hoist the combined
weight of coils and below-hook attachments is determined by the capacityofthe uncoilers and by future
plans.
The required performancewill determine the service classification of the crane. The classification
commonly depends on the weight, lifting distance, and number of lifts per hour.However,operating
speed, environment and ambient temperature, products handled, percentage of lifts made at rated
capacity, number of motor starts, reliabilityofsupplier,and availability of service and spare parts will also
influence crane selection. In manyroll forming plants, aless costly Class “C”(moderate-duty) floor or
remotely operated crane is adequate.
Forheavy-dutyperformance, aClass “D” (heavy-duty) floor,cab,orremotely operated crane should
be selected.
Cab operated cranes are controlled by amaster switch or push buttons. They usually provide up to five
speed points for hoist and three to fivepoints for trolleyand bridge travel. Floor operated cranes by a
pendant control usually provide only twohoist speeds.
The bridge travelspeed has to be restrictedtowalking speed when operated with pendulum. Remote
radio control is frequently the most economical method to operate cranes in secondarymetal
manufacturing plants.
Top-running cranes are preferredoverunderhung cranes because of simplicityinmaintenanceand rail
alignment.
8.11.2.2 Stacker Cranes
Overhead cranes with stacking attachment provide the best combination of cranes and forklift trucks.
They are ideal for plants requiring quick access to anycoils stored in racks. Therefore, stackercranes are
frequently used by the shipping depar tment of primar ymetal coil manufacturers, coil coaters, and steel
centers as shown in Figure 8.1.
Stacker cranes, however,are one of the most expensivehandling units. The stacker unit usually weighs
morethan the coil itself, requiring larger foundation and stronger structure. The highcost of the stacker
crane, the cost of storage racks, and extra spaceusually prohibit the use of this type of equipment at roll
forming plants.
8.11.2.3 Jib Cranes
This type of crane is restricted in lifting capacity and the areathey can service.Individual jib cranes,
however,can be useful in making the rollforming operator less dependent on forklift trucks or cranes
when narrow strips or coils are frequently loaded on or unloaded from uncoilers.
8.11.2.4 GantryCranes
Gantrycranes are seldom used to handle coils. However,they can be handy substitutes when the available
plant structureisinsufficient to carryanoverhead crane, in circumstances whereadding anew
foundation and crane supporting structure would be too expensive, or the plant is rented or operation is
temporary. The advantage of the gantryunit is its lower cost compared to overhead crane and that it can
be easily transferredtonew location. The disadvantage is the additional floor space taken by the rails,
possible truck traffic and walking problems because of rails protrudingfrom plant floor,and the gantry
unit is slower than overhead cranes and morecumbersome to handle it.
8.11.2.5 Monorails
Monorails with hoists are restrictedtohandle lightweight coils and only underneath the rails. This
restriction makes the monorail units the least practical for coil handling.
8.11.2.6 Yard Cranes
Different types of cranes or unloading equipment can be used for coils to be unloaded and occasionally
stored outside the plant. For reasons mentioned earlier,in-plant handling is preferred,limiting the
application of yard cranes for coil and sheet handling.
Coil Processing, Material Handling, and Plant Layout 8 -37