Packaging technology

Published: 6-02-2012, 13:08

Corrugated boxes

INTRODUCTION

Corrugated containers (erroneously termed cardboard boxes) became the shipping package of preference in the early 1900s as a replacement for wooden crates. Corrugated fiberboard packaging is, in terms of tonnage, by far the most common type of paper and paperboard-based packaging (1).

The corrugated shipping container and related inner packaging is multifunctional. Its varied uses include wrapping, enclosing, protecting, cushioning, indexing, stacking, and displaying. The basic function of the packaging is to protect the product during distribution until the product is removed from the package. The growing use of palletization in warehousing and distribution requires corrugated boxes with good stackability. Corrugated board is an appropriate material for obtaining high stackability. Product containability and cost-effective adaptation to logistics systems are important issues in corrugated-board transport design. Today’s packaging is used not only for protection, but also for promotional and adverstising support. It is a communication medium carrrying information and artwork. Printing quality has been developed to meet these needs (1).

RAW MATERIALS

Kraft linerboard derives its name from the Swedish word kraft, meaning strength. It is produced for its facial stiffness (stackability) and puncture resistance. These characteristics are achieved through use of soft-wood fibers that are long and resilient. Linerboard becomes the facings of corrugated board.

The basic raw material for liner is cellulose fiber extracted from wood chips. The chips are digested in a cooking liquor to remove lignin and resin, leaving the fiber that is fibrilated to enhance the tendency for the fibers to mat together. The fibers are pulped with water and spread onto the screen of a Fourdrinier paper machine. Water is drained, leaving the mass of fiber to form a sheet of paper that is dried and wound into rolls. Many Fourdrinier machines are over 20 ft (6 m) wide. Linerboard is graded by basic weight, which will be explained in the section on liner grades.

The natural color of pulp is tan or kraft. A small percentage of the pulp is bleached white in a chlorine bath and then converted into fully bleached white paper. Bleached white pulp is also furnished as a topping for kraft liners to produce mottled white linerboard. Paper mills sell linerboard to corrugated converting plants in units of tons.

The medium is the paper rollstock that is converted into the fluted portion of corrugated board. The medium is also known as ‘‘nine point’’ because it calipers 0.009 in. It is also termed ‘‘semichem’’ because the pulp is cooked with chemicals and then mechanically ground into fibers. The pulp, like linerboard, is converted into paper on the Fourdrinier machine; however, pulp for the medium is selected from hard-wood trees that have short fibers that hold a set better when they are steamed and fluted on the corrugator. Technical advances have made possible the use of roots and recycled containers as percentage additives to medium stock. Recycled fiber from recovered paper and board is a major source of fiber for the corrugating industry.

The universal weight for the medium is 26 lb/1000 ft2 (11.7 kg/90m2); however, minimum quantities (33 and 40 lb) of medium are used to improve flat crush, stacking, and moisture resistance in finished board.

Adhesives

Contemporary corrugator adhesives are starch-based with additives and are selected for their flow, tack, absorbtion, evaporation, and set qualities. Specialty additives may be blended with the base adhesive to improve wet strength and moisture resistance. Borax is added because it causes the starch to become a more highly branched polymer chain with higher viscosity and tack (1). Modern corrugators use as little as 2 lb (0.9 kg) of adhesive per 1000 ft2 (90m2) to combine single-wall board. Fingerless single-facers have eliminated the old problemof adhesive buildup lines (finger lines) in the finished product. The manufacture of corrugator adhesive is highly technical and is controlled through a series of extreme specifications.

Joint adhesives can be plastic based hot melts or starch-based cold melts. Both are used successfully to produce high-speed manufacturer’s joint closure (see Adhesives).

Inks

Are a product of earth elements and chemical formulations. The base carrier for modern flexographic printing inks is water laced with additives designed to enhance drying speed, produce image clarity, inhibit smearing, and eliminate spotting or blotching. Inks must be carefully scrutinized for their pH factor because acidic inks differ in performance from base inks. For example, basic inks tend to smear. Ready-to-run inks are supplied to the corrugated printers in drums of 50-lb (22.5-kg) pails. In-house ink kitchens afford the converting plant the flexibility of mixing raw materials delivered from the ink manufacturers into custom batches in which the corrugated printers can control tones, viscosities, additive selections, and many other custom characteristics that will enhance the final printed image (see Inks).

The industry’s modern ink kitchens use the Pantone Matching System (PMS) Service. An endless range of available ink colors has been opened up. The color of the print is measured by the CIE system.

Printing Plates

Modern printing plates are supplied to the corrugator mounted on poly backing, ready to be locked into the press. The industry has moved from a rather slow, methodical art form to a highly technical and efficient producer. The engraved rubber plate (die) has been replaced by a photopolymer plate that is rapidly produced through a series of computer imaging, and photoprocessing. The photopolymer plate is presently subject to ultraviolet (UV) deterioration; however, chemical suppliers of the base poly material will solve this problem soon.

Cutting Dies

Corrugated products with scores or slots with angles other than 901 must be die-cut. Cutting dies are produced for the purpose by imposing an image onto a plywood sheet, jigsawing or laser-cutting the imaged lines, and filling the eradicated space with a cutting knife or scoring rule as desired. The dies are made on curved or flat plywood, depending on the style of diecutter to be used. Stripping forms accompany cutting dies if they are to be used on automatic equipment.

Labels

High-graphics products incorporate the use of labels in conjunction with or in lieu of printing. Labels are supplied to the corrugated converters by label manufacturers. Typical specifications requested for labels are number of printed colors, paper basis weight, stock color, finish, and grade. Labels are adhered to the corrugated stock manually, semiautomatically, or fully automatically.

Additives

Finished corrugated blanks may be treated by many additives or coatings to improve water repellency, scuff resistance, and petrochemical resistance. Waxes and polymers are favored additives.

BOARD CONSTRUCTION

Corrugated board is a sandwich of one or more linerboard sheets adhered to a fluted medium. Single-face construction incorporates one linerboard adhered to the medium. Double-face, better known as single-wall, has a linerboard adhered to both sides of the medium. Additional media and linerboards yield double-wall and triple-wall (see Figure 1).

 

Various examples of corrugation
Various examples of corrugation. Figure 1.

 

Combinations of linerboard grades and flute configurations are used to generate the many variations of corrugated board. Liner weights are increased to improve board bursting and stacking strength, and flutes are modified to accommodate various compression, stack, and printing features. Two important requirements of corrugated board are flat crush and stacking strength. Flat crush measures the pounds per square inch (psi) resistance to pressure applied at a 901 angle to a horizontal sheet, thus establishing the rigidity of the flute structure. This property is changed by varying the flute outline and linear density. It can also be revised by changing the basis weight of the fluted medium. Flat crush supplies the internal resistance to squeezing forces such as feed rollers in presses and gluers. It also supplies resistance to gravitational forces imposed upon bottom sheets in stacks and bottom cartons in units.

Stacking strength measures the ability of a vertical panel to resist bowing, buckling, or collapsing from pressure exerted in line with that panel. This is regulated by varying the linerboard weights, changing flute heights, or both. Stacking strength is probably the most sought-after characteristic in corrugated cartons.

Flutes

Flutes are most essential to the characteristic of corrugated board. They supply the rigidity to the board that imparts strength with minimal weight and density. Fluting makes the product economical. Flutes are designed by height (thickness) and density (number per linear foot). Higher flutes produces a physically stronger columnar stack in line with the flutes. Denser flutes—that is, flutes that present more images per linear foot—produce more resistance across the flutes. C is the most used flute size, followed by B and E. The C flute is considered a compromise between A and B. Other, minimally used flutes include J (jumbo), which is larger than the others, as the name suggests; S flute; and F flute, which is the lowest flute height.

Higher (less dense) flutes in addition to stacking strength provide softer cushion characteristics, while lower (more dense) flutes provide greater flat crush resistance, smoother print surfaces, and crisper score lines. Flutes are often used in combinations such as BC double wall, which provides an overlap of required characteristics. B and C flutes are the most commonly produced flutes, and E is considered sparingly. Flute selection is determined by shipper needs. A fragiledecorations shipper would choose C flute for its stacking strength and cushioning qualities. A canned beverage filler would choose B flute for its end-to-end compression attributes; and a point-of-purchase display designer would select E flute for its superior printing surface. (See Table 1.)

Standard U.S. Corrugated Flutesa Table 1.

 

Standard U.S. Corrugated Flutes

aCorrugator equipment manufacturer’s single-face flute roll dimension may vary slightly to accommodate user preference.

 

MULLEN VERSUS EDGE CRUSH

Carrier regulating agencies require a board upgrade to accommodate increased loads and increased box sizes analogous to the idea that a 3/4-in. (19-mm) plywood sheet is stronger than a 1/4-in. (6.35-mm) sheet. Paper mills fulfill this requirements by producing various-weight liner grades, corrugated converters combine board using proper heavier grades to accommodate the need for stronger containers.

Liner Grades

The universally accepted test for corrugated board has been the Mullen test (TAPPI test method T-810), which measures the resistance of the board to withstand a puncturing pressure measured in pounds per square inch (psi) or metric kilopascals (kPa). Linerboard grades have been manufactured to meet specific Mullen requirements. Increased Mullen demands increased linerboard strength, which is accomplished by increasing the mass of the linerboard measured in pounds per thousand square feet (lb/1000 ft2) (kg/90m2).

A major modification to containerboard was initiated in the 1980s, when paper mills developed a process that enhanced linerboard material, giving it an ability to withstand crush or compression examinations at lower basis weights. Table 2 compares STFI crush performance of standard to high-performance liners. Note the improved STFI in high-performance liner.

STFI Crush Performance of Standard to High-Performance Liners Table 2.

 

STFI Crush Performance of Standard to High-Performance Liners

 

The product high-performance linerboard provides a serious potential for user satisfaction and improved economics. New linerboard concepts prompted the corrugated industry trade associations to sponsor proposals to truckand rail-carrier committees to consider classifications recognizing edge crush as a test criteria. Proponents for the new test methods argued that edge crush is more customer-oriented and that it permits more latitude for manufacturers to design and supply boxes that meet customer performance criteria. Rules committees of truck and rail carriers accepted the proposals, and in 1991 they approved the edge-crush test (ECT) as an alternative test method for containerboard.

Edge-crush Test

This measures the resistance of the containerboard to edgewise compression. Ring-crush and STFI tests measure the resistance of the linerboard and medium. These tests are performed to give the linerboard and corrugated manufacturers relative material comparisons. The edge-crush test includes the value of the medium’s resistance to compression as well as the linerboard. It should be noted that these tests can, and are, performed on standard weight liners as well as on high-performance liners (see Edge-crush concept).

Medium Grades

General industrial principle requires use of the same medium weight (26 lb/1000 ft2) (11.7 kg/90m2) for all board grades; that is, liner weights change to generate increasing board tests, but the medium remains the same. There are some approved exceptions that call for upgrading medium to improve flat crush and moisture resistance. Two upgraded medium weights are 33 and 40 lb.

REGULATIONS

Freight carriers and government agencies control the regulations for the container industry. The major regulation is encompassed in Rule 41 (Uniform Freight Classification) established by the National Railroad Freight Committee (2). This regulation is closely paralled by Item 222 (National Motor Freight Carriers). Table 3 outlines minimum standards. Triple-wall and solid-fiber standards have not been included in this chart.

Minimum Standards for Construction of Corrugated Boxesa Table 3.

 

Minimum Standards for Construction of Corrugated Boxes

 

aNote 1—Burst test: (a) Tests to determine compliance with the bursting test requirements of Table A must be conducted in accordance with Technical Association of Pulp and Paper Industry (TAPPI), Official Test Method T-810; (b) a minimum of six bursts must be made three from each side of the board, and only one burst test will be permitted to fall below the specified minimum value. Board failing to pass the foregoing test will be accepted if in a retest consisting of 24 bursts (12 from each side of the board), not more than four burst tests fall below the specified minimum value.

Note 2—Edge-crush test: (a) Tests to determine compliance with the edge crush requirements of Table B must be conducted in accordance with Technical Association of Pulp and Paper Industry (TAPPI), Official Test Method T-811; (b) a minimum of six tests must be made and only one test is permitted to fall below the specified minimum value, and that one test cannot fall below the specified minimum value by more than 10%. Board failing to pass the forgoing will be accepted if in a retest consisting of 24 tests, not more than four tests fall below the specified minimum value, and none of those tests fall below the specified minimum value by more than 10%.

Rules prescribed by these agencies outline requirements that determine proper liner weights and manufacturing specifications. All corrugated boxes made to conform to the regulations carry a printed certificate identifying the boxmaker and appropriate board grade as shown in Figure 2. Note the apparent difference between the burst-test and the edge-crush certificates.

 

Boxmaker certificate
Boxmaker certificate. Figure 2.

 

Several other regulatory agencies are included depending on shipper requirements, including

  • Department of Transportation—Code of Federal Regulations No. 49 (Transportation)-Pointing specifically at hazardous materials 
  • International Air Transport Authority (IATA)—concerned with air transport 
  • International Maritime Authority—water cargo 
  • United Parcel Service (UPS)—ground deliveries of o150 lb 
  • U.S. Postal Service—Domestic Mail Manual 

CONVERTING OPERATIONS

Corrugated fiberboard boxes are manufactured in a corrugated board plant or in a sheet feeder plant. The corrugated board plant consists of the corrugator, which produces flat sheets of corrugated fiberboard, and the converting equipment where the corrugated sheet is converted into corrugated board boxes by printing, cutting, scoring, and gluing. Sheet feeder plants are smaller factories that convert board into packaging for shorter run length orders, for quick deliveries, and for a local market.

Contemporary box plants vary widely in size and capability. A small sheet plant may ship one truckload of cartons per day while the megacontainer plant will ship 50 truckloads per day. Corrugated requirements are so diverse that a wide variety of company sizes is a desirable asset to the industry.

Corrugator

This is the major piece of equipment in a box plant. The machine converts mill-supplied roll stock (linerboard and medium) into flat sheets. It varies from 50 to 100 in. plus (12.7–25.4 m) in width, and most are over 300 ft (91.5 m) long. Wide computer-managed corrugators operating at speeds of up to 1000 lineal feet per minute are capable of producing four truckloads of corrugated board per hour.

The single-facer (wet end) of the corrugator converts the medium into fluted paper and adheres it to the inside liner of the corrugated sandwich. Next, a double backer roll is applied as the outside liner, and finally the sandwich is run over dryer plates and delivered to the dry end. Cross-corrugation scores may be applied and the board is trimmed into two-dimensional blanks in preparation for delivery to the plant for further conversion into a box.

Scheduling (trimming) a corrugator requires skill and training because variations of liner combinations, quantity requests, and blank dimensions are endless. Modern computer-trimmed corrugators are capable of producing several hundred setups per day.

Printer-Slotters

These machines print, slot, and score flat banks in preparation for folding and joining into finished boxes. Sized blanks are delivered from the corrugator prescored for flap and depth dimension. The operator, generally one of a twoor three-worker crew, sets scoring and slotting heads at proper dimensions to cut required length, width, and joint dimensions into the carton. The operator then hangs the premounted printing plates on the print cylinders, fills the ink wells with desired colors, and begins production.

These machines are referred to by the number of colors they are capable of printing in one pass plus cylinder diameter and machine width. Small-dimension machines are obviously better suited for producing small boxes, and so on. A majority of presses today are two-color; however, presses in up to six colors are available.

Corrugated printer-slotters are letterpress printers; however, most current equipment is a flexographic variation that incorporates the use of an analox roller with water-base inks versus the old doctor and impression rollers with oil-based ink. Flexographic printing offers many advantages over letterpress, including operating speed, clarity, registration, trapping, drying, and cleanup. Printer-slotters employing flexographic printing can produce an average size-box (e.g., a 24/12-oz beverage box) at approximately 15,000 per hour.

Flexofolder-Gluer

The Flexofolder-Gluer (FFG) incorporates the addition of an automatic folder–gluer system with the printing unit, which permits the completion of most cartons on one machine. The equipment has been available since the 1960s, when flexographic printing with high-speed drying made it possible for cartons to be folded immediately after printing without smearing. These machines may also be equipped with automatic bundeling and unitizing systems. The most advanced FFG can run up to speeds of 26,000 boxes per hour. Boxes can be produced for any application.

Folder–Gluers

These are designed to finish boxes in a straight line or right angle. Both are extremely efficient at folding panels and applying adhesive to produce finished cartons that require minimum or no final sealing. Predecorated, slotted, and or die-cut blanks are belt fed through the folding sections; glue is applied at required spots; and finished cartons are stacked at the finish end. Most equipment is designed to accept a wide variety of sizes both in the machine direction and across the machine.

Die Cutters

Die cutters are required for all parts that are scored or slotted other than 901 or in line with press direction. Intricate die cut interior parts and box designs are a very common part of the industry.

Flatbed die cutters are designed to produce accurate products. They vary from small hand-fed machines that are limited in speed to the operators performance (about 500 blanks per hour) to high-performance automatic equipment that include multicolor printing selections. Flatbed cutting dies are reasonably priced. The process for flatbed die cutting closely resembles cookie cutting. The die board is locked into a chase that holds it in a firm position. Corrugated board is registered under the die; and the machine is closed, striking the die impression into the board.

Rotary die cutters are best used to produce parts at high speeds. They are not as accurate as flatbed machines; however, they can be designed to accept large blanks. Rotary cutting rule is inserted into curved plywood and then locked onto the die-cutting cylinder. An impression is made into the board when a blank is passed between the cut die cylinder and an opposing thick polyblanketed impression cylinder.

Slitters

Slitters have a series of wide rotating shafts to which scoring and slitting collars (heads) are attached. These heads can be moved by the operator to change dimensions. Most slitters are manually fed; however, some are equipped with automatic feed sections. Slitters are used to reduce large sheets to smaller blank dimensions, add scores to existing blanks, and prepare small runs for further processing. Slitters are very versatile machines. Small sheet plants may be totally equipped with a slitter a printer–slotter and a taper.

Partition Slotters

These machines slot corrugated pads in preparation for assembly into partitions.

Partition Assemblers

These machines automatically assemble slotted racks into cell-divided partitions for use in separating delicate parts such as glass bottles.

Tapers

These machines apply tape fed from rolls onto prefolded cartons to form a manufacturer’s joint. Standard tape widths are 2 in. (5.08 cm) or 3 in. (7.62 cm). Tapers are handfed semiautomatic or hopper-fed automatic. The machine is an economical piece of equipment that can be adjusted and set very quickly. Taped joints represent a minimal amount of todays production because of their relatively slow production speeds and higher costs compared with glued joints. Glued joints also perform better in regulatory transit tests.

Stitchers

These devices apply staples cut from a roll and are driven into the joints of prefolded boxes. Stitched joints have limited use in today’s market; they are used mostly with government-grade boards and specialty wet-strength containers.

Coaters

These machines are operated at box plants or, in many cases, at specialty plants that process coatings on finished containers. These specialty plants function as a separate entity to the corrugated industry; that is, they seek customers for their process, mostly from the fish, poulty, and produce industries; purchase finished containers from corrugated converters; and add the required coatings (waxes and plastics) to the containers. The industry specializes in wet-strength and moisture-barrier containers.

Curtain coaters feed box blanks under a curtain of liquid coating (molten poly) that coats one side of the blank and passes it to a drying section. Some coaters are capable of flipping the blank to deposit a coating on both sides. Cascaders pour wax coatings onto finished containers. Wax dippers immerse finished containers into tanks of molten wax and then hang them to dry. The process looks very much like your local laundry.

Laminators

Litholaminators have become an important adjunct to the high-graphics corrugated producer. This equipment rolls adhesive onto a printed litholabel, registers the label under the substrate, drops the substrate onto the label, and rolls the combined stock to achieve 100% adhesion and eliminate air bubbles. Litholaminators are designed to feed flat banks, including joined (knocked-down) boxes. Stock-laminators are designed to laminate varied substrates together to achieve added thickness or uncommon stock variations. They simply pass a flat blank over a surface roll that is revolving in a pan filled with adhesive, register the now adhesive coated substrate with a second substrate, and pass the combined sheet through compression rollers. The finished product is usually stacked immediately, flipping every other handful to reduce warp. Single-face laminate is a is a hybrid process that begins as a traditional fluted medium adhered to a single linerboard; but in the place of a second board, a preprinted sheet of paperboard is laminated to the outer surface.

Miscellaneous Equipment

A well-equipped corrugated plant will require additional materials handling and finishing equipment, including lift trucks, conveyors, bundelers, unitizers, bailers, load turners, eccentric slotters, quick sets, strippers, and band saws, plus many custom machines such as riviters.

MANUFACTURER’S JOINTS

Joints applied by the corrugated manufacturer provide the most practical way to convert a two-dimensional product into a third-dimensional one. Manufacturer’s joints, as the name implies, are created by the box manufacturer. Box users torque containers open, fill them, and seal them closed by gluing, stapling, or taping. Edges that meet during closure are called seams.

Joints are glued, taped, or stitched. Glued and stitched containers employ a 11/4-in. lap that is a contiguous part of a length or width panel that will be glued or stitched to the opposing panel when the panels are folded to meet. Glued joints became the joint of preference in the 1960s. Almost all high-speed flexo presses and folders are equipped to run glued joints. Some volume box users are equipped with wraparound machines that fold flat blanks around a product and seal joints and seams in place. This process eliminates the need for a manufacturer’s joint from the box manufacturer, which in some cases saves cost and in all cases produces a more tightly wrapped package. Stitching is not used in food packaging products.

Glued and stitched joints are produced with the lap on either the inside or the outside of the container. Both have their advantages. Inside laps present a finished outside edge that presents a better appearance and allows more print area. Outside laps leave a smooth surface on all four inside panels of a carton. (See Figure 3.)

 

Examples of joints
Examples of joints. Figure 3.

 

DIMENSIONING

Three-dimensional cartons are designated by lengthwidthdepth. Length and width are the longer and shorter dimensions of the opening of a box, and depth is the third dimension. Two-dimensional parts are designated by supplying the flute direction as the first dimension. Dimensions can be specified for either the inside or the outside of a box. Accurate inside dimensions must be determined to ensure the proper fit for the product being shipped or stored. At the same time, palletizing and distributing the boxes depends on the outside dimensions. The box manufacturer must be informed as to which dimension is most important to the customer (3).

Corrugated board has a definite caliper, which was noted in Figure 1; consequently, scoring allowances must be considered when dimensioning boxes and interiors. One-half thickness of board is lost for each 901 bend. See an example in Figure 4.

 

Score and fluting
Score and fluting. Score B flute 1/8 in. (3.175mm) thick at 3 1/16 in. × 4 1/8 in. (7.79cm × 10.48cm × 7.79 cm) to achieve inside dimensions of 3 in. × 4 in. × 3 in. (7.62cm × 10.16cm × 7.62 cm). Figure 4.

 

CORRUGATED ECONOMICS

Carton economics demands that solid geometric figures (pertaining to three dimensions, LWD) must be reduced to plain geometric figures (pertaining to two dimensions, LW) for manufacturing specifications and cost analysis. (See Figure 5).

 

Example of reduction to plain geometric figure
Example of reduction to plain geometric figure. Figure 5.

 

Having established the single-plane dimensions of a container (LW), the area per piece can be established. This area is calculated in square inches per piece, which is generally referred to in square feet per 1000 blanks, that is, L in.Win. divided by 1441000 = square feet (ft2)/ 1000 pieces.

Corrugated box costs are functions of raw material, plus manufacturing, administrating, and delivering costs; consequently, a major objective in box design is to maximize fill area and minimize the blank dimension required to do so. Several principles to consider that will accomplish this maxim follow:

  1. The most economical RSC (regular slotted container) formula is L=2W=D. 
  2. Rectangular RSCs are more economical than square RSCs. 
  3. Square tubes are more economical then rectangular tubes. 
  4. Width is the least economical dimension of an RSC. 
  5. Depth is the most economical dimension of an RSC. 

BOX STYLES

Box styles and interiors are too numerous to discuss in this article, and can best be referred to in the Fibre Box Handbook (4). Most designs are designated by their closure feature. The most used box is the regular slotted container (RSC), which features the most economical use of board from the corrugator. All flaps are equal in depth, and the width of the outer flaps equals one-half that of the containers, so they meet to form a seam at the center of the box when folded. An alternative to the RSC is a wraparound design. The manufacturer supplies a flat blank to the packer. This is folded around the product and overlap is sealed. One-piece packaging to meet specific market needs, such as the carry-home pack for bottles of wine, shows considerable design ingenuity (1).

Carton designers using CAD/CAM computer programs generate intricate new designs that enhance packing programs and support marketing schemes. Today’s world of discount stores requires containers that function as sales tools that fully describe the product enclosed as well as protecting the product for delivery to the consumer.

RECYCLING

Corrugated material, made from a natural renewable resource, is frequently manufactured from recycled fiber, is often reused many times, and then is recycled for use in other packaging materials. Used corrugated containers are very adaptable to recycling; in fact, they represent the major source of recycled paper today. Over 76% of recycled containers are reclaimed for paperboard used to make more corrugated boxes (5). Box manufacturers have learned to make stronger boxes using less raw material. This is called source reduction. Corrugated packaging also allows for significant source reduction by eliminating the need for overwraps and secondary packaging (5). The industry is working on problems that occur during the repulping process. New adhesives are being developed that will help prevent ‘‘stickies’’ from forming that can clog the papermaking equipment. Stickies can originate from wax coatings, labels, and adhesives. Figure 6 illustrates a rough floorplan of a typical box plant.

 

Typical plant floorplan

Typical plant floorplan. Figure 6.

 

INDUSTRY FUTURE

The corrugated industry is mature, meaning that it has developed a full share of the possible market and that most volume advances come through volume increase in existing markets. An unavoidable outcome of the globalization of the world economy is an escalated need for distribution of goods in terms of ready-made products from the globabl enterprise to its customers in the global market as well as extensive transport of materials, parts, and subsystems from external and/or internal suppliers to assembly plants. Effective packaging and logistics solutions have become key factors in order to maintain or improve competitiveness of these enterprises. These patterns also affect national and small- to medium-sized enterprises. A significant driving force is the quest for the optimal package. It is not only necessary that the package provide fundamental functions, but also that it be accomplished at the lowest possible cost with a minimum of environmental impact. A key factor is to minimize the mass of the package. A benefit to the industry would be the reduction of the amount of raw material used. An additional important factor is to realize that in the future the sources of raw materials may change and vary in quality. These factors emphasize the necessity to use effectively the fiber strength of the raw material, and current research is aimed in this direction (6).

Undoubtedly the most beneficial adjustment the consumer will receive is the move to high-performance linerboard and the corresponding change from burst test to edge-crush test. This very significant change will ultimately result in not only lower direct costs but also lower freight and handling costs. The combination of stronger paperboard at lower basis weights will also result in a reduction of waste tonnage and pulp consumption. High-performance linerboard will improve machine efficiencies and printing capabilities.

High-graphics containers are claiming a larger share of the market. Packagers are accepting the corrugated container as a sales tool in addition to its use as a shipping container. Exotic labeling equipment and preprinted liner laminates are becoming more common to the industry, and the trend continues toward faster in-line converting machines that incorporate printing, slotting, die cutting, folding, and gluing into one piece of equipment.

GENE A. FOSTER

Middlesex Container Company,

Inc., Milltown, New Jersey

Updated by Staff

<
Marcia

17 июня 2012 14:31

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Good information. I am in warehousing of corrugated finished product and was hoping that I would find stacking standards require in warehousing.
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Mrinalini

21 июня 2012 10:23

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Hi Marcia

The stacking standard depends on weight of a filled box .
As a indicative standard, consider following parameter & decide on specification
1. max. load on the bottom most box should not exceed 100 kg.
2. Stack ht. should not exceed 2100 mm (considering manual handling)
3. Compression strength of box = 3 times max. load on the bottom most box for nonfragile product
<
srinivasa raju

18 июля 2012 03:04

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please let me the difference between regular slotted and universal slotted.
<
Folder gluer machine manufacturers

22 августа 2012 02:40

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