Stacking dolls, or matryoshka, are a popular collector's item. They usually consist of colorful images of identical people or animals painted on two-piece lacquered wood containers of various sizes. The smallest figure fits into the next biggest figure until all four of the smaller dolls end up nested inside the largest one.

The world of packaging works in a similar manner. Products are inserted into paper boxes, plastic bags, blister packs or other types of primary packaging. Small packages, called cartons, are placed into bigger secondary packages, called cases, which in turn are loaded onto large pallets.

Forklifts, tugs and other material handling equipment load the pallets onto railroad boxcars, trucks or ocean-going containers for shipment. When the pallet arrives at a warehouse or the stockroom of a retail store, the process is reversed: the cases are unloaded from the pallet and the cartons are unpacked from the cases.

The process of cartoning, case packing and palletizing is called end-of-line packaging. Although cartoners, case packers and palletizers are the final step in most packaging lines, they play an important role in reducing time to market by getting products out the door and into customers' hands.

Nontraditional retailing strategies and new marketing paradigms are putting more pressure on manufacturers of consumer goods, such as electronics, hand tools, lightbulbs, pens, razors, toothbrushes and toys. To address those challenges, more and more suppliers of end-of-line packaging equipment are harnessing robotics to develop flexible systems that can accommodate frequent changeover.

Changeover Is Critical

"The driving factors in end-of-line packaging [today] are finding the balance between flexibility of equipment, product speed, and ease of operator interface," says Bill Buck, marketing and applications project engineer at Schneider Packaging Equipment Co. (Brewerton, NY). "These factors drive the overall profitability of the end-of-line system.

"The end-of-line system must be capable of changing over between product configurations, and do so in a minimum amount of time," Buck points out. To address those needs, packaging machine builders are incorporating the latest in programmable devices, human-machine interfaces, and servo mechanisms to provide equipment that is robust, easy to use and simple to change over.

"Product life cycles have shortened and companies want to run multiple sizes and products in a packaging system," notes Joel Anderson, marketing manager at SWF Cos. (Elk Grove Village, IL). "The time required to change from one size or product to the next is critical to maintain productivity."

Some packaging lines take minutes, others hours to change over. These changes are usually done by operators, which introduces a potential error source.

"Customers also want the flexibility to add new products in the future," says Anderson. "Companies are asking packaging machinery suppliers to provide machines capable of changing sizes with the push of a button or with the minimum use of tools and operator interfaces."

End-of-line packaging equipment includes cartoners, case packers and palletizers. Cartoning machines are devices that erect and close sheets of thin, flat material, called carton blanks, or folded and side-seam sealed cartons. Case packing machines are similar to cartoners, but they typically work with a heavier type of paperboard. Palletizing machines form, dismantle or secure pallets and other loading units.

In addition to cartoners, case packers and palletizers, end-of-line packaging systems include strapping, stretch wrapping and sealing equipment. According to the Packaging Machinery Manufacturers Institute (PMMI, Arlington, VA), the end-of-line equipment market is nothing to sneeze at. Indeed, it's a billion-dollar industry.

Demand for cartoning and multipacking machinery is expected to reach $200 million in 2006. The PMMI predicts that $369 million in machinery for case and tray forming, packing, unpacking, closing and sealing will be shipped next year. And, the market for palletizing, depalletizing and pallet unitizing equipment will exceed $400 million. However, end-of-line packaging machines are not considered to be as glamorous or sexy as upstream equipment, such as formers, fillers and labelers.

"Upstream equipment generally [places] product into a primary package that will be used by the consumer," notes Buck. "End-of-line packaging equipment takes those [items] and packages them into manageable bundles so that they are easily shipped and protected during shipment."

"[Because it touches the product] primary packaging machinery is designed and built around certain criteria, such as FDA requirements, stainless steel construction, wash down resistance, sealed bearings and resistance to certain cleaning agents," adds Anderson. "Many times, secondary packaging machinery does not have to meet such stringent requirements, as these machines don't touch the actual product; it has already been packaged in the primary container."

New Retailing Environment

With the advent of big-box stores, the Internet and other new distribution channels, the retail marketplace has become more competitive than ever. To differentiate themselves from their competitors, retailers demand unique packaging configurations. The days of one-size-fits-all packaging has gone the way of dime stores, corner grocery stores and small hardware stores.

"Today, shelf presence is driven by the marketers' need to outshine the competition," says Kallol Bagchi, an industrial automation and process control research analyst at Frost & Sullivan Inc. (San Antonio). "It is the appeal to the customers' eyes, designed to attract attention with color and emotional appeal.

"But, the consumer is not consuming immediately, so the appeal is not to taste buds but to the consumers' visual sense of taste," adds Bagchi. "In a category where product differentiation is slight but demand is high, packaging carries a larger burden of marketing. This is where upstream packaging machines such as formers or fillers make a huge impact."

Case packers or palletizers are workhorses that make the roles of retail stores and warehouses easier. For example, a palletizer that can successfully apply a radio frequency identification (RFID) tag to palletized goods minimizes logistical nightmares in the supply chain but never makes it to the customer, so it is not considered as glamorous.

"It is something like a precious porcelain cup packed in a Styrofoam," explains Bagchi. "Everyone appreciates the porcelain cup, but not the Styrofoam that helps pack and ship the cup safely across [continents or oceans]."

Traditionally, most consumers didn't pay attention to shipping pallets either, because they didn't influence their purchase decision. "However, with the growth of discount retailers and warehouse clubs that display the whole pallet of product to the consumer, manufacturers are [becoming more] aware of the look of the pallet," claims Kevin Kozuszek, marketing manager at Kuka Robotics Corp. (Sterling Heights, MI). "The pallet then becomes the visual selling point, and more marketing effort and creative design is given to it accordingly."

Giant retailers are having a huge effect on end-of-line packaging systems. Companies such as Costco Wholesale Corp. (Issaquah, WA), Home Depot Inc. (Atlanta), Kmart Corp. (Troy, MI), Staples Inc. (Framingham, MA), Target Corp. (Minneapolis) and Wal-Mart Stores Inc. (Bentonville, AR) wield tremendous clout today.

In a recent PMMI study, 54 percent of respondents claimed that their major customers exert an influence on their packaging machinery buying decisions. In addition, 40 percent reported that their influence is increasing.

"The growing trend toward mass customization in the packaging industry is changing the shapes and sizes of boxes and containers that come through production lines," says John Holmes, packaging segment manager at PIAB Vacuum Products (Hingham, MA).

New demands for packaging flexibility are forcing consumer goods manufacturers to focus more attention on the ability to quickly change over lines to accommodate constantly shifting needs. For instance, many retailers are seeking smaller counts-per-case or counts-per-display.

Consumer goods manufacturers are being forced to operate an increasing number of packaging runs per line to meet the proliferation of product varieties, sizes and configurations demanded by super stores, club stores and large chains. According to Chuck Yuska, PMMI president, there's an unprecedented need in the industry for "greater flexibility in handling multiple packaging formats through quicker changeovers."

"Some stores have shelf space for four-packs of product, where others want six-pack or even eight-pack configurations," explains Schneider's Buck. To address that flexibility, his company offers a case packing machine that can package each of these pack-pattern configurations through a simple combination of menu changes and machine adjustments. "One person can change the machine to a new size, and have it up and running in 15 minutes or less," Buck points out.

"Packagers are being faced with a growing number and variety of requirements dealing with package size, configuration, bundling, coding, labeling, display packaging and tamper-evidence," says Yuska. "In some cases, the customer actually specifies the type of machine to be used.

"As an essential part of end users' efforts to reduce package costs, improve product shelf appeal, improve ease of product handling, and conform to major customers' packaging requirements, packagers are continually experimenting with and developing alternative package designs, sizes and materials," adds Yuska.

Endless Package Variety

Secondary packaging is usually intended for either marketing applications, such as cartons for displaying product on store shelves, or distribution applications, such as corrugated cases.

A carton is a container made from thin paperboard that typically measures between 0.25 and 1 millimeter in thickness. Fiber-chipboard cartons usually consist of a single sheet of fiberboard that is delivered to the end user in the form of flat carton blanks.

Cartons are primarily used for displaying products on store shelves. "They typically feature a chipboard stock that can support printing and graphics," says Dave Schuh, vice president of sales and marketing at MGS Machine Corp. (Maple Grove, MN).

However, a carton is not the same as a case. While a carton is made from thin paper material, a case is typically larger, stronger and sturdier because it's made out of corrugated cardboard that is 3 to 6 millimeters thick.

Corrugated packaging has an arched layer, called fluting, between smooth sheets, called liner. The corrugated cardboard most commonly used to make cases has one layer of fluting between two smooth sheets. It is a durable and lightweight material.

There are many different types of corrugated board stock available, each with different flute sizes and thicknesses. In addition, there are almost as many different designs and styles of cases available to packaging engineers. However, regular slotted cases are the most popular, says SWF's Anderson.

"They are efficient and economical, because they feature a one-piece construction," explains Anderson. "Various styles and flap-folding sequences can create additional stacking strength and case durability."

Cartons and cases also have distinctive types of flaps. For instance, cartons typically are closed with tuck-in style flaps or two glue-sealed outer flaps that fully or partially overlap. Cases, on the other hand, typically feature a pair of flaps that meet in the middle and do not overlap.

Traditionally, the process of erecting, forming and gluing cartons or cases was a manual, labor-intensive operation. Today, many manufacturers use high-speed machines, such as cartoners and case packers, to automate the entire process and boost throughput.

A stack of blanks is placed at one end of the machine. The machine pulls them out one by one, erects and forms the carton or case, inserts the product and seals the bottom of the carton or case with either glue or tape.

The basic mechanics and motions are similar for both cartoners and case packers. For instance, product is loaded either vertically or horizontally into the container while another container is being formed ready for loading. Both types of equipment then automatically seal the containers.

"What differs is the container material and the speeds at which the machines run," says Schneider Packaging's Buck. "Cartoners are typically continuous-motion machines. Case packers are often intermittent-motion machines."

Pallet Productivity

Shipping pallets are one of the unsung heroes of the packaging world. Loading docks and warehouses are full of the ubiquitous devices.

A pallet is a portable, horizontal, rigid platform used as a base for assembling, storing, stacking, handling and transporting goods as a unit load. Most pallets are made out of wood, but they can also be metal or plastic. Typically, a pallet contains a raised superstructure that allows it to be lifted and moved by a forklift without damaging any cases.

Palletizing may seem like a simple concept, but according to MGS Machine's Schuh, it's more like an art. "Cases must be carefully arranged in a pattern conducive to balancing the load for strength," he points out. "The process is similar to arranging bricks to build a strong wall." Typically, stretch wrap is placed around the outside of the pallet load to provide extra stability.

Palletizers are special packaging machines that can build a complete unit load on a pallet. Although the most common application is for cases, some palletizers can also handle sacks and bags. Advanced palletizers can build loads that combine homogenous, mixed or random products. The number of cases loaded on each pallet often varies. It depends on the size of the case, its weight, its contents and the pallet pattern used.

"Palletizing is traditionally the end of the production process in manufacturing," says Kuka Robotics' Kozuszek. "It is the transition point between the manufacturer or distribution center and the end user or retailer."

According to Frost & Sullivan's Bagchi, several trends are driving demand for palletizing machines, such as an increased shift toward higher outputs and lower floor space, and an increased shift toward flexibility in terms of handling cases of different sizes and shapes. "With the mandate for RFID by both Wal-Mart and the U.S. Department of Defense, [machines that] can affix an RFID tag after palletizing the goods are going to be the next generation of palletizers," notes Bagchi.

A wide variety of conventional palletizers and robotic palletizers are available. Conventional palletizers position cases into a unit load through a series of cross-push motions to develop a product pattern. Palletizing robots use a robotic arm to position cases with either a mechanical clamp-style gripper or vacuum suction cups. Both articulated and gantry robots are used for packaging applications.

According to SWF's Anderson, conventional palletizers are less expensive than robots and are more appropriate for a single-size case or few pack (pallet) patterns. However, they require a great deal of maintenance and take up more floor space. Because they cannot handle multiple lines, conventional palletizers typically are less flexible.

"Traditional packaging machinery typically requires changes to the infeed system, internal modifications to accommodate different product and case sizes, and sometimes the purchase of another machine," Anderson points out. On the other hand, he says robotic palletizers are much more flexible, so they're ideal for handling multiple package sizes. They are easily expandable, offer higher productivity and much lower maintenance requirements.

"Though not a rigid rule, conventional palletizers are more commonly used for applications requiring higher speeds or involving products with reduced packaging," says Pat O'Connor, product manager for palletizing systems at FKI Logistex North America (St. Louis). "Robotic solutions generally fit lower-speed lines and situations where the palletizer needs to handle multiple lines simultaneously. Because of their typically smaller footprint, robotic solutions are also an option where floor space is at a premium."

"With a conventional palletizer, a lot more pieces of machinery touch the case," notes Mark Andrews, sales manager of case palletizing products at Columbia Machine Inc. (Vancouver, WA). "A robot just picks a case off a conveyor and places it onto the pallet. Conventional palletizers also require case guides, which can be time-consuming to change. It can take 15 to 20 minutes to change over a line."

Not surprisingly, more and more packagers are turning to robots every year. In fact, the Robotics Industry Association (RIA, Ann Arbor, MI) claims that North American orders for packaging and palletizing robots grew 50 percent in 2004. At this month's PackExpo trade show in Las Vegas, most experts believe there will be more robots in the exhibit hall than conventional palletizers.

Highly flexible robotic systems are an ideal way to build mixed pallet loads demanded by today's retail environment. Robots typically are slower than conventional palletizing equipment, but they offer much faster changeover times. "It can be cheaper to operate two robots on two lines as opposed to one conventional palletizer on a single line," says Kozuszek. "The multiple robot scenario also adds to the flexibility of manufacturing.

"Robots provide the ability to work with multiple SKUs to build pallets to order," Kozuszek points out. However, he says the challenge is to develop software that can build random or mixed pallet loads that address the retail industry's need for smaller, more diverse packaging runs.

"The benefits of choosing robotic palletizing are mostly seen in flexibility and reduced floor space," explains Schneider Packaging's Buck. "For example, one robot arm can be used to pick product from up to four different conveyors, and palletize the product onto one, two, three or four different pallet discharge conveyors. Four dedicated conventional palletizers would be required to accomplish this application."

Robots can also be quickly reprogrammed to accommodate new pack patterns. "Robotic palletizers can easily integrate different pallet sizes and types, making the end-of-line system flexible and robust," concludes Buck.