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carton that can easily be set up by hand. Diagonal scores

permit the tray to be glued and delivered in a collapsed

form. Web corners could be incorporated with additional

modiﬁcations.

Tray cartons that require no gluing at the point of use

(e.g., the six-corner carton of Figure 6) are used exten-

sively for manual loading. The cake, pie, or pastry carton

employed by the local bakery is the best example of the

utility of these designs. Garments and other dry goods

are often packed, especially when purchased as gifts,

using two-piece cartons that comprise two collapsible

glued trays. Tray cartons are also widely used for products

that can be automatically packaged. Doughnuts and ﬁsh

sticks are examples of products commonly packaged in

tray-style cartons with attached covers. Cartons similar to

that shown in Figure 4 are used for products of this type.

Most display cartons for smaller candy packages also fall

into the tray category.

Special Construction

Special construction is a classiﬁcation employed for car-

tons that do not ﬁt tray or tube descriptions, or that

represent sufﬁcient departures from normal tray or tube

practice. A blister package that employs a combination

of heat-seal-coated paperboard and a clear thermoformed

plastic blister is a good example of a special construction

(see Carded packaging). The automatic-bottom carton

shown in Figure 7 combines elements of a side-seamed

tube carton with those of a top-load carton and requires

no manipulation to form the carton bottom. When the

collapsed shell is opened, the bottom panels lock into

place. This carton is used extensively for fastfood carryout

packaging. It is also popular for hardware items.

The bottle-wrap carton in Figure 8 is an example of the

many wraparound carrier cartons used for multipacks

of bottles, cans, or plastic tubs (see Carriers, beverage).

These cartons are either locked or glued after being

wrapped around the primary packages.

The tube, tray, and special carton styles depicted and

described here are broadly representative of the great

variety in shapes and sizes produced by the folding-carton

industry. Customization of design for function or appear-

ance is a signiﬁcant advantage of folding cartons.

CARTON MANUFACTURING PROCESSES

After a paperboard grade has been selected for a speciﬁc

carton style and use, a variety of manufacturing options

are available for converting that board into cartons.

Although it is a highly unusual carton that requires

each one of the steps or stages described below, all are

commonly employed to produce folding cartons in today’s

market.

Extrusion Coating

This technique involves the coating of one or both sides of

the paperboard web with a relatively thin (generally less

than 0.001-in. (25.4-mm)) layer of a thermoplastic polymer

(see Extrusion coating). Low-density polyethylene (LDPE)

is the most commonly used extrusion coating for folding

cartons and provides a cost-effective means of obtaining

excellent protection against water resistance as well as a

fairly good water-vapor barrier. LDPE is also used as a

heat sealant (see Sealing, heat), particularly when two-

side coatings are employed. When the use temperature of

the package exceeds 1501F (651C), HDPE or PP can be

used to raise the acceptable use temperature to 2501F

(1211C). These two polymers also provide improved

grease resistance. Coating board with PET can raise the

use temperature to over 4001F (2041C), suitable for most

‘‘dual-ovenable’’ applications. Coextrusion, in which back-

to-back layers of two plastics are laid onto paperboard,

Figure 6. Six-corner carton: (a) blank; (b) carton erected for

Figure 7. Automatic-bottom carton: (a) blank; (b) carton glued

for shipping; (c) bottom view of erected carton.

238 CARTONS, FOLDING

makes it possible to take advantage of the special proper-

ties of some exotic plastics, such as nylon, that by them-

selves will not adhere to paperboard.

Laminating

The earliest means of signiﬁcantly enhancing the proper-

ties of paperboard was the combination with other mate-

rials through lamination (see Laminating). The most

commonly used laminating adhesives are water-based

glues (see Adhesives), or thermoplastic polymers. Materi-

als laminated to paperboard include high-quality printing

paper for enhanced graphics capabilities (see Paper),

grease- or water-resistant paper for improved barrier,

aluminum foil for barrier or aesthetics (see Foil, alumi-

num), and ﬁlm (sometimes metallized) for barrier or

aesthetics (see Metallizing).

Printing

Prior to the printing operation, paperboard is handled in

web form. A decision must be made to continue in web

form or convert the web to sheets before printing and die

cutting. This choice is primarily dictated by the printing

technique chosen (see Printing). Sheeting is most often

done at the carton-producer’s facility. A small segment of

the industry purchases board sheeted at the paperboard

mill.

The main processes for carton printing today are offset

lithography, ﬂexography, and gravure. Letterpress and silk

screen are used to a limited extent. The most recently

introduced process, digital printing, can be used for short

print runs and for customizing packaging in already pre-

made bulk. Printing involves solid print, text, illustrations,

and diagrammatic representatios. Brand positioning can

have a major inﬂuence on the printing design. Functional

needs have to be taken in to account. Products that retain

ink odors require special attention in choice of inks and

printing methods. Products that are packed hot may need

rub-resistant print surfaces (1).

With respect to quality of reproduction, there is overlap

in what can be achieved today with the various printing

processes. Gravure was considered best for solids, whereas

offset lithio was considered best for halftones. Today, offset

gravure and conventional gravure with eletrostatic assist

may improve gravue halftone reproduction. In the past,

offset lithio would be used to print a design on a box of

chocolates and the rest of the printing would be done

by sheet-fed gravure. This was necessary to prevent the

occurrence of residual odors that would be retained from

the lithio ink and would be a hazard to chocolate. Today,

there is a wide choice of offset lithio ink and drying

systems that assist drying. Today, presses are ﬁtted with

coating units that can apply UV-cured varnishes that are

water clear, have high gloss, and are rub-resistant.

It is still true that cylinders are relatively more ex-

pensive for gravure than plates for lithio and ﬂexo, but

they are longer-lasting and therefore competitive when

longer runs are required.

Silk screen printing has always been known for its

ability to print thick ﬁlms of ink. UV systems can be used

in silk screening, and this has the advantage of rapid ink

drying. A range of special effects is possible and incliude

raised images, such as Braille, warning symbols, highly

opaque prints, and high-luster varnish and textured

ﬁnishes (5).

Cutting and Creasing

Following the printing operation, individual cartons are

cut from webs or large sheets and creased or scored along

desired folding lines. Reciprocating ﬂat-bed or platen

cutting is almost invariably used to cut and crease sheets

printed by offset lithography. In this technique, an accu-

rately positioned array of steel cutting knives and scoring

rules (see Figure 9) is pressed against a printed sheet of

paperboard. The knives penetrate through the paperboard

to cut out the pattern of the carton. Rules force the board

to deform into channels in the counter plate, producing

controlled lines of weakness (scores) along which the

board will later predictably bend or fold. Alternatively,

scores can be produced by cutting partially through the

paperboard or by alternating uncut segments with com-

pletely cut-through segments.

In years past, knives and rules were separated and

held in place by hand-cut blocks of dimensionally stable

hardwood plywood. Hundreds of individual blocks were

required for dies incorporating 10 or more carton posi-

tions. Greater accuracy and consistency as well as sub-

stantially reduced die preparation time is being used

today through the use of computer-controlled laser die

cutters. The laser beam is used to cut slots in large sheets

of the same special plywood. Knives and rules are cut and

bent automatically or manually and placed by hand into

the slots. Crease or score quality has been improved

Figure 8. Bottle wrap carton: (a) blank; (b) erected carton.

(Bottles omitted for clarity.)

CARTONS, FOLDING 239

through the use of computer-controlled counter-plate ma-

chining and accurate pin-registration systems.

Transport of printed sheets in a sheet-fed platen cutter is

accomplished with mechanical grippers that hold the lead-

ing edge of the sheet. Small nicks in the cutting knives

result in uncut areas that keep the full sheets intact and

permit transport from the cutting and creasing station to

the stacking station. Large stacks are then removed from

the machine; and unwanted pieces of board, called broke,

are stripped from the cut edges of the cartons, yielding

stacks of printed carton blanks. Newer sheet-fed platen

cutters incorporate automatic stripping of broke between

the cutting and stacking stations. Platen cutters are also

employed to cut and crease paperboard printed in web form.

In the past, these cutters were often placed out of line from

normally faster-running presses. Speed increases permit

economical in-line placement, which is common today.

Rotary cutting and creasing offers the advantage of

higher speeds than reciprocating platen cutting, but at

greater cutting die cost. Matched machined cylinders used

for ﬁxed carton sizes are most often placed in-line with

printing operations. Both electrical discharge and me-

chanical machining are used to produce the knives, rules,

and score channels in these matched cylinders.

Rotary cutting dies have also been developed for sheet

and web cutting and creasing that are produced by

pattern chemical etching of thin metal plates. Cutting

and creasing patterns are coated with chemical-resistant

materials, and chemicals are used to reduce the thickness

of the plate in the unprotected areas, resulting in raised

rules. Creases are formed by pushing the paperboard with

the rule of one plate into a channel formed between two

rules of the second plate, a conﬁguration quite analogous

to that of platen creasing. Cutting, however, is quite

different; cutting rules on opposing plates are offset

slightly from each other. As these rules rotate, approach-

ing each other closely but not touching, they compress the

board. Compressive forces within the board cause it to

rupture, yielding cut edges. For sheet-fed cutting, these

etched ﬂexible dies are mounted on large cylinders which,

like sheet-fed offset plate cylinders, leave a gap between

leading and trailing edges. This gap accommodates sheet

feedup and variable repeats. For web cutting, however,

leading and trailing edges must be butted to correspond to

the continuously printed webs. Die mounting techniques

as well as carton layout on the web are the keys to the

successful operation of this approach.

Two additional specialty converting steps are accom-

plished on cutting and creasing equipment: foil stamping

and embossing. Foil stamping involves the use of heat and

pressure to transfer a thin metallic or pigmented coating

from a carrier ﬁlm to the carton surface to obtain patterned

decorative effects. When this is done in combination with

embossing, reﬂectance and gloss are combined with raised

image effects for enhanced graphic presentation. Emboss-

ing alone can generally be accomplished on standard

die-cutting equipment. Foil stamping and detailed, deep

embossing requires the ability to heat the stamping and

embossing plates. This is most commonly accomplished on

a second pass through specialized equipment.

HOT-MELT APPLICATION

Hot melts (see Adhesives) can be preapplied at this or a

later production point using knurled wheels or timed

guns. The hot melt is later heat-activated on the packa-

ging machinery to effect sealing. Although hot melt appli-

cation on the packaging machine is common, some carton

users ﬁnd it advantageous for the carton manufacturer to

preapply the hot-melt adhesive.

Windowing or Couponing

When product visibility is desired, a hole is cut out of the

carton blank. To protect the product or prevent it from

spilling out of the carton, pieces of an adhesive pattern

are applied around the edge of the opening, a rectangular

piece is cut from a roll of ﬁlm and is then pressed in place.

Registered application of printed ﬁlms or printed coupons

in roll form to interior or exterior surfaces adds value and

function to the carton. Devices are also available that

adhere coupons supplied in sheet form.

Gluing

Although more and more packaging machinery is de-

signed to accept ﬂat carton blanks (see Cartoning

Machinery), gluing still represents a major and important

converting operation. The simplest operation converts a

ﬂat blank into a side-seamed tube or glued shell (see

Figure 2b). Carton blanks are removed one at a time

from a stack and carried by sets of endless belts. Station-

ary curved plows move one or more panels of the blank out

of the original plane to either prebreak scores or form the

glue seam. Prebreaking of scores assists packaging-

machine operation, since the force required to bend a

previously bent score is greatly reduced. Sealing is accom-

plished with cold glues, hot melts, or heat sealing of

polymers. Side-seamed cartons are discharged into a

shingled delivery that provides compression and time

to set the bond; case or bulk packing for shipment follows.

Gluers in which the cartons move in a continuous

straight line, transported by belts, are known as

straight-line gluers. Although straight-line gluers are

most commonly used to produce glued shell-type cartons,

attachments provide the ability to produce automatic-

bottom as well as certain collapsible-tray styles. Paper or

paperboard bridges can be attached to main panels during

Figure 9. Flat-bed cutting-die schematic.

240 CARTONS, FOLDING

straight-line gluing. For simple styles, the feeding of

carton blanks into the gluer does not need to be timed

into speciﬁc folding actions. Complicated folding devices

may dictate that blank feeding be timed, which generally

reduces speeds. Compound folds in both directions on the

blank cannot be handled by straight-line machines.

For more complicated carton and collapsible-tray

styles, right-angle gluers are employed. As the name

implies, midway through the machine the travel direction

of the blank is changed by 901. All parallel folds can be

made in the direction of blank travel, resulting in simpli-

ﬁed machine setup and more positive and accurate fold-

ing. Generally, speed is limited by the transfer section,

which changes blank travel direction. Right-angle gluers

combine ﬂexibility and precision in the manufacture of

complex folding cartons.

Setup and nested tapered trays are also produced in

folding-carton manufacturing plants for shipment to cus-

tomers. These trays are produced on plunger-type gluing

equipment that is designed to accept either blank or roll

feeds. Blank-fed machines ﬁrst apply adhesive, then form

the tray as a moving plunger forces the previously printed

and creased blank through a stationary folding and form-

ing device. Roll-fed machines incorporate printing as

well as cutting and creasing units in-line prior to gluing.

Nested trays are not as space efﬁcient as unglued blanks;

they do, however, have application in uses for which it

would be uneconomical or impractical to operate a forming

device at the location of use. Paperboard french-fry scoops

and sandwich containers used by fast-food outlets are good

examples of these trays.

DISTRIBUTION OF THE PRODUCT

The consumer eventually takes possession of the cartoned

product. This can take place in a number of ways. For self-

service retailing, the appearance of the package is impor-

tant. Damaged or faded cartons probably would not be

purchased. For a pharmaceutical product, the package

must have a hygienic image. For supermarket transit, the

package must be conveniently handleable, easy to open,

and recyclable. A new consideration is to assure the

consumer that the product is genuine and not counterfeit.

Several techniques are available: for example, printing an

identiﬁcation on the carton using transparent varnish

that is visible under UV light; incorporating a clear

mark that is similar to a watermark; ﬁngerprinting using

near-IR technology; and the use of RFID labels on pallet

loads and transit packs (6).

BIBLIOGRAPHY

Paul Obolewicz, ‘‘Cartons, Folding’’ in The Wiley Encyclopedia of

Packaging, 2nd edition, John Wiley & Sons, New York, 1997,

pp. 181–187.

Cited Publications

1. M. J. Kirwan, ‘‘Folding Cartons’’ in M. J. Kirwan, ed., Paper

and Paperboard Packaging Technology, Blackwell Publishing,

London, 2005.

2. D. Hunter, Papermaking—The History and Technique of an

Ancient Craft, Dover Publications, New York, 1978, pp. 471,

552, 577.

3. TAPPI Ofﬁcial Test Methods, Provisional Test Methods, Histor-

ical Test Methods, TAPPI Press, Norcross, GA; subject index

May 2008, www.TAPPI.org.

4. Kliklok Packaging Manual, Kliklok Corporation, Greenwich,

CT, 1983 revision, p. I.

5. ‘‘Rotary Screen Printing,’’ Packaging Magazine 7(3), 22 (2004).

6. ‘‘RFID Radio Tagging,’’ Paper Technology 44(10), 3–4 (2003).

CARTONS, GABLETOP

R. E. LISIECKI

Ex-Cell-O Corporation

Updated by Staff

INTRODUCTION

The gabletop folding format is one of the oldest and most

basic end closures possible for a paperboard package. The

ﬁrst patent dates back to 1915 and was issued to J. Van

Wormer for what he called a ‘‘paper bottle and later

Pure-Pak (1). However, 20 years passed before the ﬁrst

commercial installation began to operate at a Borden

Company plant, after the patent was acquired by Ex-

Cell-O Corp. In 1997 Elopak bought Ex-Cell-O Packaging

and the Pure-Pak license (2). Today a number of manu-

facturers supply machinery to make gabletop cartons for

milk and other still liquids.

Early gabletop milk packages were precision-cut fold-

ing boxes with an adhesively sealed side-seam and bottom

closure and a stapled top closure (see Figure 1). Semi-

formed cartons were dipped in hot parafﬁn for sanitization

and moisture prooﬁng prior to ﬁlling. Tops were stapled.

The ﬁrst packages had no convenient opening device.

Subsequent designs had convenience openings based on

secondary patch seals adhesively secured to either the

inside or outside of a side panel. The secondary patch was

eventually eliminated in favor of an integral pouring

spout.

The modern gabletop carton retains a simple basic

geometry but includes design reﬁnements acquired over

50 years of development and commercial use. The transi-

tion from the wax-coated carton to precoated paperboard

came in 1961, necessitating several new developments in

package and materials technology (see Extrusion Coating;

Paperboard). The use of precoated board eliminated par-

afﬁn, wire, and adhesives from a ﬁlling plant’s inventory.

Also eliminated were the associated mechanical systems,

including carton-coating chiller units, wax melters, adhe-

sive applicators, and related instrumentation. Precoated

blanks simpliﬁed the form/ﬁll/seal process and permitted

the design of faster, more-efﬁcient equipment with ﬁlling

rates up to 300 cartons per minute. To retain the essential

pouring-spout feature, an antisealant or abhesive was

CARTONS, GABLETOP 241

developed. This allowed the carton top seal to be tightly

sealed, yet easily opened (see Figure 2). Gable top cartons

are also available with screw caps. These caps have

external tamper-evident security plastic rings, which

have to be broken in order to access the contents.

FABRICATION

A typical blank for a quart (946.25 mL) gabletop container

is shown in Figure 3. With a panel width of 2.764 in.

(7.02 cm) and a body height of 7.375 in. (18.73 cm), the

apparent contained volume of 56.34 in.

(923.25 cm

) falls

short of the quart volume of 57.75 in.

(946.35 cm

). The

needed extra volume is found in the bulge of the side

panels after ﬁlling, which leaves the ﬁlled product line

below the top horizontal score, providing ‘‘headspace’’

necessary to compensate for foam generated during ﬁlling

and to allow for a certain amount of splash as the ﬁlled

container is conveyed through the top heat-sealing ma-

chine function.

The standard square cross section of the quart

(946.25 mL) carton is used for a full range of containers

from 6 ﬂ. oz (177.4 mL) through the Imperial quart

(1182.8 mL). Other cross sections in the same carton

format have panel widths of 2.240 in. (5.69 cm), 3.3764

in. (8.576 cm), and 5.531 in. (14.05 cm), with container

volumes from 4 ﬂ. oz (118.3 mL) through one gallon

(3.785 L). For quart-series containers, the typical paper-

board structure consists of 195–210 lb (88.5–95.3 kg) per

ream paperboard with a coating of 0.0005 in. (12.7 mm) of

polyethylene on the outside surface and 0.001 in. (25.4 mm)

of polyethylene on the inside surface. Other structures

that include aluminum foil, ionomer (see Ionomers), and

other barrier materials are also used (Figure 4).

A modiﬁcation of the existing design is the Sahara

bottom, which reduces water absorption by the raw edge.

It is a feature that can be applied on the forming and

ﬁlling machine. It has the effect of raising an uncoated

paperboard edge in the sealed bottom away from contact

with a wet surface. It is claimed that this reduces uptake

of water by the raw edge of paperboard by 80% and

prevents the bottom of the carton from becoming satu-

rated with water (3).

Coated-paper containers for liquids provide relatively

short shelf life. It is possible, however, to tailor the

Figure 2. Current gabletop container. It is polyethylene-coated

with a pitcher-spout opening device.

Figure 1. Early gabletop container. It is parafﬁn-coated with a

patch-type opening device.

Figure 3. Typical proﬁle for the quart (946-mL) series.

242 CARTONS, GABLETOP

container to its contained product. Liquids with high

solids content, such as milk or fountain syrups, are

relatively easy to contain, since there is little product

penetration of cut edges or random ﬂaws in the coating.

Other products require (a) near-hermetic seals, dictating a

continuous high barrier such as aluminum foil, and (b) the

elimination of cut edges in the ﬁnished containers.

This can be accomplished by a number of mechanical

techniques including (a) skiving and hemming of the cut

edge of the side seam and (b) reﬁning the folding of the

bottom closure to protect the cut edge from liquid contact.

These techniques permit the successful packaging of oils

and alcohol-bearing liquids with little problem. Special

treatment of the paperboard may also be necessary to

ensure package stability. A form/ﬁll/seal machine erects

cartons from ﬂat blanks; and after ﬁlling, it seals the

bottom. This machine is capable of handling 24,000 car-

tons per hour, similar to that of a modern canning line (2).

Today’s form/ﬁll/seal equipment contributes to shelf life by

enclosing the processing line. Some machines feature air

ﬁltration and carton sanitization systems.

APPLICATIONS

At its peak, the gabletop carton was the premier package

for milk and other ﬂuid products in the United States.

Process reﬁnements permitted its use for other likely

products, such as fruit juice and fountain syrups, and a

few unlikely products, such as candy and epsom salts.

Newer applications include the packaging of cooking oil,

liquid egg products, and dry food. Tetra Rex, 750 g in 2-L

cartons, has been used to launch a high-fruit-content

muesli. Freeze-dried vegetables are packed in large

Pure-Pak cartons for the catering and institutional mar-

kets (3). In the United States, the plastic blow-molded

bottle (see Blow Molding) has become the container of

choice for gallons (128 ﬂ oz or 3.785 L) of milk, but the

paperboard gabletop carton is still favored for smaller

sizes.

BIBLIOGRAPHY

R. E. Lisiecki ‘‘Cartons, Gabletop’’ in M. Bakker, ed., The Wiley

Encyclopedia of Packaging Technology, 1st edition, John Wiley

& Sons, pp. 152–154; 2nd edition, A. J. Brody and K. S. Marsh,

eds., 1997, pp. 187–189.

Cited Publications

1. J. Van Wormer, U.S. Patent 1,157,462 (October 19, 1915).

2. M. J. Kirwan, ‘‘Paperboard-based Liquid Packaging’’ in M. J.

Kirwan, ed., Paper and Paperboard Packaging Technology,

Blackwell Publishing, Ltd., London, 2005.

3. Packaging News, 2 (May 2000).

CASE LOADING

WALTER WARREN

Salwasser Manufacturing

Company, Inc.,

Decatur, Georgia

The corrugated case is still the most universally accepted

method of packaging and shipping products from one

destination to another (see the Boxes, corrugated article).

It offers excellent product protection in both storage and

shipping with the additional beneﬁt of full-panel graphic

identiﬁcation or advertisement exposure. The terms case

packing, case loading, and casing all refer to the method of

placing product into corrugated shipping containers. This

can be accomplished by the fundamental method of hand

loading or by semiautomatic or automatic case-loading

machinery. This article is structured to demonstrate a

normal sequence of conversions from hand loading to fully

automatic loading. Cases, whether manually or automa-

tically loaded, are classiﬁed as top load, side load or end

load. The top-load case has ﬂaps in the largest panel and is

the most expensive because of the large ﬂap area. An end-

load case, with ﬂaps on the smallest panel, is the least

expensive. Proper machinery selection depends on many

variables such as the type of package, style of case,

production rates, automatic versus semiautomatic ma-

chinery, ﬂoor space, and rate of investment return. The

following basic case-loading methods are discussed below:

hand loading, horizontal semiautomatic case loading,

horizontal fully automatic case loading, vertical drop-

load and gripper-style case loading, wrap-around case

loading, and tray former/loader.

HAND LOADING

This is the simplest version of case loading. It requires

limited machinery involvement, but it is highly labor

intensive. As packages are delivered to the packing area,

personnel manually open, load, and seal the corrugated

cases using a variety of closing methods including cold

glue, hot-melt glue (see the Adhesives article), tape (see

Figure 4. A typical six-ply laminate.

CASE LOADING 243

the Tape, pressure sensitive article), or metal staples (see

the Staples article). Cold and hot-melt adhesive applica-

tors are most common (see the Adhesive applicators

article). Replacing the case-closing operation with an

automatic top-and-bottom case-sealing machine is the

ﬁrst step in automation. This unit can always be used

later as the packaging line converts to fully automatic. To

decrease labor and increase production, the manual load-

ing operation is replaced with a semiautomatic case-load-

ing machine integrated with the existing top-and-bottom

case sealer.

HORIZONTAL SEMIAUTOMATIC CASE LOADER

With this type of equipment, the product is loaded from

the side (see Figure 1). This method offers considerable

ﬂexibility in obtaining the desired case pattern, which is

deﬁned as the position or orientation of cartons grouped

inside the case. It is ideally suited for handling cartons,

cannisters, cans, or any product that takes a rigid or

semirigid shape. The most common product handled is

consumer-type cartons, which are loaded in a variety of

conﬁgurations and counts. The semiautomatic case loader

requires an operator to open manually a ﬂat premade

corrugated case, fold the bottom ﬂaps, and place it on the

machine-loading tube or funnel ready for package inser-

tion. All other machine functions are performed auto-

matically. All other machine functions are performed

automatically. Typically, an operator can open approxi-

mately 10–12 cases/min. Higher case rates would require

fully automatic case-loading machinery, which is de-

scribed below. Package speeds in excess of 500/min are

obtainable, but the number of cartons per case and the

dexterity of the operator dictate if it can be done semi-

automatically.

The basic unit includes an infeed conveyor to receive

packages and deliver to the machine accumulator sec-

tion, where the product is grouped or stacked to the

prescribed case pattern and loaded into the already

opened and formed corrugated case. Single tier and

multitier case patterns are easily accommodated. Multi-

tier applications require the cartons to be stacked prior to

loading. Functionally, the infeed conveyor delivers car-

tons to a lifter plate, where the prescribed number is

accumulated. Through a pneumatically operated cylin-

der, the cartons are lifted and deposited on stacker bars.

The lifter returns and continues this cycle until the

correct number of cartons have been grouped in front of

the loading tube. A pneumatically operated side-ram

cylinder pushes the ﬁnal load into the case. Because of

the slower case rates of semiautomatic machines, air

cylinders are normally used for the product lifting and

side-ram load motions. Mechanical cam/crank and/or

servo drives usually perform these same motions on

automatic high-speed machines. Many machine conﬁg-

urations and accessories are available including multi-

lane units for higher package production rates. Standard

upstream ﬁlling and packing machinery usually dis-

charge product in a single lane; the use of multilane

casers would require some type of package lane dividing

systems. Many packages must be repositioned to coincide

with the case pattern; this is accomplished through rail

twisters, upenders, turn-pegs, and so on. Converging

equipment is also available if the output from several

upstream packaging machines must be converged into

the caser single-lane infeed. After ﬁnal loading, the ﬁlled

case is lowered onto a short discharge conveyor ready for

ﬁnal case sealing. The existing top-and-bottom case

sealer can be used or any other type of sealer. This

approach to case loading is ideal for lowercase rate

applications. It requires minimal capital investment,

but it is a major step in automation. At this point, the

horizontal semiautomatic case loader has eliminated the

hand-load operation and reduced the personnel to one

operator. The next sequence in automation replaces

the operator with an automatic corrugated-case erector,

forming a fully automatic case-loading system.

STEPS TOWARD FULLY AUTOMATIC CASE LOADING

There are normally two approaches to automatic case

loading a fully automatic integrated system including a

case erector, loader, and sealer or a case erector loader

that uses an existing case sealer. Most case-loading ma-

chinery is manufactured in modular design to allow the

proper equipment selection for the application. Considera-

tion should always be given to how existing equipment can

be used in conjunction with new equipment. A decision to

automate, and how to do it, is based on many considera-

tions: case rates in excess of 10–12 min, high package-

production rates, packages more easily loaded automati-

cally, large-size cases more easily handled automatically,

labor reduction, ﬂoor space reduction, and increased line

production and efﬁciency.

Case Erector/Loader. This machine is equipped with a

ﬂat-corrugated storage magazine that will, on demand,

extract a case from the magazine, open it, fold in bottom

Figure 1. Horizontal semiautomatic case loader.

244 CASE LOADING

ﬂaps, and automatically place it on the caser loading tube

for ﬁnal package insertion (see Figure 2). After loading,

the ﬁlled case is lowered onto a discharge conveyor and

transferred into a new or existing case-sealing machine.

Case extraction and opening are the most critical func-

tions of an automatic erector. Corrugated cases have a

built-in memory (resistance), and proper blank scoring

will increase opening efﬁciency. Although more expensive,

experience has proven that equipment offering mechan-

isms to prebreak or restrict the case back panel during

opening are well worth the investment. Generally, va-

cuum/pneumatic mechanisms seem to function well up

to approximately 20 cases/min. Higher case rates nor-

mally require a mechanical/vacuum/pneumatic combina-

tion with several stations for case extracting, opening, and

loading. Both horizontal and vertical case magazines are

available. The automatic case erector can be added to

an existing semiautomatic case loader with its separate

sealer, or it can be offered as part of a new integrated

system interfaced with the existing case sealer. The case

erector eliminates the operator who would otherwise open

cases manually; therefore, the erector ﬂat-case storage

magazine must have sufﬁcient capacity for at least a

30–60 min supply. If ﬂoor space permits, additional maga-

zine capacity is encouraged. Vertical-style magazines are

offered with bulk-storage feed systems where several

stacks of cases are loaded on a ﬂoor-level conveyor and

on demand, feed automatically to the magazine (see

Figure 3). A variety of case erectors is offered for various

case rates of r30 cases/min.

HORIZONTAL AUTOMATIC CASER ERECTOR/LOADER/

SEALER

The ﬁnal approach in automation incorporates a comple-

tely integrated system. A new automatic case extractor/

sealer can be integrated with an existing semiautomatic

caser to form a fully automatic line, but the case erector/

loader/sealer is normally purchased new as a part of the

complete packaging line. Case extracting/loading func-

tions are the same as those discussed above, but after

loading, the ﬁlled case is transferred horizontally through

the glue-application section and into the compression

unit using heavy-duty continuous-motion cleated chains.

Minor case ﬂaps are folded closed and major ﬂaps are

opened ready for adhesive application. After gluing, sta-

tionary plow rods fold in major ﬂaps as the case is

deposited into the intermittently driven side-sealing com-

pression unit (see Figure 4). A secondary set of top chains

may be employed to ensure that the case is presented

squarely to the compression unit. Vertical compression

units for use in overhead ﬁlled-case conveying systems

reduce initial ﬂoor-space requirements. The compression-

section length is a function of the type of adhesive used

and its corresponding drying time. Both hot-melt and cold-

glue adhesives are commonly used (see Adhesives).

Hot-melt adhesive has a faster setup time and requires a

relatively short compression section, usually 4–5 ft (1.2–

1.5 m). Cold-glue adhesive takes longer to set and requires

more compression-section length. The hot-melt adhesive

unit takes less space, but it is somewhat more expensive

than the cold-glue system. Polyvinyl chloride (PVC) seal-

ing tapes are becoming an attractive sealing method for

various reasons, and most automatic machines can be

equipped with tape heads in place of glue heads (see

the Tape, pressure-sensitive article). Compression-section

length can usually be reduced, because no drying time is

required. As with all automatic machines, the ﬂat-corru-

gated case magazine storage capacity should be large

enough to ensure that an operator is not constantly

Figure 2. Case erector loader.

Figure 3. Vertical magazine.

CASE LOADING 245

replenishing the supply hopper. A complete automatic

system offers many advantages including higher case

rates, increased line efﬁciencies, labor reduction, and the

operational technology of programmable logic controllers

(PLC). The machine functions are now computerized and

programmed accordingly. This information can be coordi-

nated into the main control center, providing valuable

information to the production department. This new

electronic technology offers many specialized options,

such as operator interface panels, data highway informa-

tion systems, and troubleshooting diagnostic displays. In

summary, the horizontal fully automatic case opener,

loader, and sealer can receive product from upstream

packaging equipment and delivering that product to the

shipping department in a sealed corrugated case. This is

all accomplished in a relatively small area at speeds of

r30 cases/min. Continuous-motion machines are avail-

able for case rates in excess of 50/min but require con-

siderably more ﬂoor space.

VERTICAL CASE LOADERS

This method of case loading is used primarily in the

beverage, glass, can, and plastic container industries,

where fragile or irregular-shaped containers require some

special packing considerations. As with the horizontal case

packers, the product is delivered to the machine infeed

conveyor from upstream ﬁlling equipment to the accumu-

lator section. Tabletop chain is commonly used in delivering

the product to reduce backpressure during the load cycle

and for infeed washdown applications. Cylindrical-type

products are divided automatically into several lanes using

oscillating or vibrating dividers to form the accumulated

load pattern. Irregular-shaped containers such as blow-

molded plastic bottles must be divided by special equip-

ment. When all lanes are ﬁlled in the accumulator area, a

formed corrugated case is positioned underneath the load-

ing mechanism ready for depositing. At that point, retract-

able shifter plates in the accumulator area move out, which

allows the containers to drop vertically through ﬁngers into

the cells of the case (see Figure 5). Special ﬁngers guide and

reduce side shock to the containers during the load cycle.

The use of cells or corrugated partitions inside the case to

eliminate container contact is based on product-protection

requirements. Usually glass containers have partitions,

and plastic containers do not. Case rates of up to 25/min

are achieved for intermittent motion machines, whereas

newly developed continuous motion equipment approaches

40–50/min. The vertical case loader can be interfaced with

many different kinds of corrugated-case erecting equip-

ment. Manual case set up and placement under the load

area tied into a case sealer is one alternative. Another

technique used by the glass and plastic bottle industries, is

Figure 4. Horizontal fully automatic case loader.

Figure 5. Vertical drop-load case packer.

246 CASE LOADING

to ship empty bottles in cases to the ﬁlling plant where they

are emptied, ﬁlled, and loaded back into the reshipper cases

using a top-case sealer. A third method is to incorporate an

automatic case erector, vertical loader, and sealer. The

machinery selection is based on ﬂoor space, capital invest-

ment, type product to be handled, and most important, the

case-rate requirement.

Another vertical-load method for handling fragile or

heavy containers and ﬂexible pouches is one that utilizes

vacuum or mechanical grippers to lower the containers

into the case (see Figure 6). This approach is ideal for

containers that can be gripped at the top, such as glass or

plastic bottles. The containers are delivered and accumu-

lated in the same manner as with the vertical drop loader,

but a special plate or load head incorporating vacuum or

mechanical grippers moves down and picks up approxi-

mately 12 containers at a time and places them in the

opened corrugated case. Generally, both the drop-load and

vacuum or mechanical gripper-style machines are offered

in multiload station modules to obtain speeds of 40–50

cases/min with automatic case erectors. Although slower,

ﬂexible pouches, cartons, and irregular shaped containers

are currently being loaded in the same manner using

robotic multiaxis motions with a variety of vacuum and

mechanical grippers. Robotic case loading is emerging as a

viable alternative to conventional vertical loading because

of its product handling versatility, less ﬂoor space, and

quick changeover.

Equipment is also available that loads cartons, cans,

tapered cannisters, and so on vertically up through the

bottom of a case. This method is usually limited to top-load

cases, but it does offer the advantage of eliminating

possible package repositioning. A case is extracted and

opened in the conventional method over the accumulated

product. On demand, the product is lifted up into the case,

which is then transferred horizontally into the sealing

section. For the most part, both horizontal and vertical

case-loading equipment are of the intermittent-motion

design, which is somewhat speed limited. Requirements

for higher speed have led to the development of faster

ﬁlling machinery and continuous-motion casing equip-

ment that runs in excess of 2400 cases/min and 1200

boxes/min. This special machinery is an integrated system

handling multiple cases. Continuous-motion horizontal

case-loading equipment using both premade RSC and

wraparound blank cases (see the Boxes, corrugated arti-

cle) have exceeded the 50/min range. These rates apply to

some special tray forming/loading applications as well.

Because upstream ﬁlling equipment for cartons and

ﬂexible packages has not achieved the high rates of the

can and bottling ﬁllers, the requirement for continuous-

motion carton-type casers has been limited.

AUTOMATIC WRAPAROUND CASE LOADING

An entirely different approach to case loading uses a ﬁve-

panel corrugated blank instead of a ﬂat premade corru-

gated case with the manufacturer’s joint already glued.

Vertical or horizontal corrugated blank-storage magazines

are employed that extract the blank and position it

between chain lugs by either vacuum or mechanical

mechanisms. During this motion, both side panels are

folded into a vertical position forming half the case. The

blank is then positioned in front of the loading machine

where the product is either pushed onto the blank or

dropped vertically (see Figure 7). After loading, the top

panel is folded down over the product and ﬁnal ﬂap folding

and gluing is completed. Depending on the type equip-

ment, the manufacturer’s joint is then glued and folded

down to one of the vertical panels for ﬁnal sealing. Wrap-

around casers are usually larger and more complex than

loaders for premade cases owing to the additional func-

tions that must be performed, but depending on the size of

the case, there may be some economical board-cost ad-

vantages using a ﬁve-panel blank. Pneumatically oper-

ated machines can achieve speeds up to 20 cases/min;

higher rates of approximately 30 cases/min would require

a more mechanical/pneumatic design. Continuous-motion

wraparounds are available for special applications with

speed requirements in the 40–50/min range. Both hori-

zontal and vertical blank storage magazines are available

Figure 6. Vertical gripper-style case packer.

Figure 7. Wraparound case loader.

CASE LOADING 247