What are pallet load conveyors? 3

How are pallets used to move products? 4

What exactly are pallets? 5

How are pallets made? 6

What pallet designs are available? 8

Pallet pooling 10

Captive pallets 11

What are the typical sizes for pallets? 13

The right pallet matched with the right conveyor is only the beginning 14

What to look for in a pallet conveyor system supplier 17

Conveyors move products. That “product” can be sand to a barge, sorted packages to a container that will load on a truck or airplane, ice cream to a filling operation, or fresh chicken to cold storage. Each one of these uses can be a highly-specialized mode of material handling.

One family of conveyors and material handling devices deals specifically with handling product that is conveyed on a pallet.

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The load on the pallet can be stacked with boxes going into a grocery warehouse, components for air conditioners on an assembly line, packaged fresh chicken, or filled orders leaving a warehouse for delivery to a retail center.

Typically the load is unitized rather than in bulk form. Imagine what a forklift might carry. Conveyors can take care of that load without the human interface.

Pallets are used to support, contain, transport, protect, collect or capture loads as they progress through a manufacturing or distribution facility.

They can be reusable. Or they can be disposable. There are situations where pallets are a captive part of an automated machining line. Pallets allow loads to be lifted, conveyed, transported and deposited by pallet jacks, fork lifts, conveyors, Automated Guided Vehicles (AGV) and other material handling devices.

Typically, pallets are used to collect a specific, unitized load. That load can be held in place for transportation using stretch wrapping, adhesive, physical supports, banding, and other means of stabilization. The pallet protects the bottom of the load; the support for the load keeps it stable on the pallet, square and in the correct orientation.

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Pallets can be made from various materials. The most common material is wood. However, metal (steel or aluminum), cardboard, wood composites and plastic are common as well. Each has specific uses and advantages.

Export Rackable Pallet

Corregated Pallet

Presswood Pallet

Double Faced Plastic Pallet

Steel Pallet

The advantage of wood pallets is cost. Wood is inherently the least expensive material. It provides the combined attributes of stiffness and durability as well cost effectiveness.

However, the advantages of other materials can make them better suited than wood for uses that require special attributes such as extreme durability, dimensional stability, manufacturing precision or ease of cleaning and sanitation. Both plastic and metal pallets can be appropriate to these needs.

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Pallets typically adhere to the Uniform Standard for Wood Pallets by the National Wooden Pallet and Container Association (NWPCA). That standard is shown here. Pallets are identified as a stringer or block design and, depending on access for entry by a fork lift, can be listed as a “two-way” or “four-way” design.

Pallets can also be designed with a “single” or “double face” depending on whether the pallet is constructed with both a top and bottom deck or just one deck. A “reversible” pallet can be used with either the top or the bottom supporting the load while a “non-reversible” pallet has only one side that can be used as a top deck.

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Other design considerations can be important when deciding on the proper pallet to use. Weight, dimensional accuracy, and environments that are harsh or corrosive may be important factors. If the pallet is going to be used in a conveyor system, the bottom of the pallet is a critical element.

One approach to conveying pallets that are not consistent in size or quality is to use a “slave board.” A slave board is a single sheet of thick wood as large as the largest pallet that will be conveyed using it. The slave board typically is captive or dedicated to the conveying system.

A company that is going to export products on pallets may need to use a pallet that complies with export shipping standards such as the International Standards for Phytosanitary Measures No. 15 (ISPM-15). This standard “is to prevent the international transport and spread of disease and insects that could negatively affect plants or ecosystems.” (See this Wikipedia article for more detail.)

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An alternative to buying pallets is a concept called “pallet pooling.” Pallet pooling involves leasing or renting pallets from a pool shared with other companies. Not only does this keep a steady stream of pallets available; damaged pallets are repaired by the pooling provider. The pooling process can also help with an expanding and contracting need for pallets.

To learn more about pallet pooling, here is a discussion by Supply Chain Digital.

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Many industries use “captive pallets.” These are pallets and dunnage that are specifically designed for a product or component. They never leave the system. That can involve pallets that move product step-by-step through a machining process and, with the process completed, are emptied and returned to the beginning of the process to be refilled. A forklift manufacturer has specified this concept on a machining line for components used in their equipment.

Captive pallets are used by the automotive industry, among others, to carry specific parts from a sub-contractor to the main assembly line in another plant. They are then returned to the contractor to be refilled with components and sent back to the assembly line.

A large motorcycle manufacturer uses captive pallets to ship completed cycles to dealers’ showrooms. The motorcycle is removed by the dealer, the pallet collapses and is then shipped back to the manufacturer by common carrier for re-use.

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There are some commonly used standard sizes of pallets. In North America, 48” x 40” is the main pallet size. The 48” dimension is the length of the stringer boards on either side of the pallet. As listed by the International Organization for Standardization (ISO) there are six (6) pallet sizes recognized including North America (as detailed above), Europe & Asia, Australia, North America-Europe-Asia, Asia and Europe. Here is an overview of the ISO publications relating to pallets.

As detailed above, however, pallets also can be very specialized to be integrated with very specific

The configuration of the pallets used in a conveying system could determine the type of conveyor in the system.

For instance, if the bottom boards of the pallets are parallel to the direction of travel, a Chain Driven Live Roller (CDLR) conveyor is often used. If the bottom boards are perpendicular to the direction of travel, a multi-strand chain conveyor may be the best choice. It is essential to delve into this level of detail in the earliest stages of purchasing a pallet conveying system.

Once the basic conveyor system is defined, there are other considerations as well.

For instance, pallet conveyor tends to be heavier because of the weight carried on each pallet through the system.

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Maintaining the correct squareness or alignment of the pallet relative to the conveyor system can be important. Simple additions such as positioning stops and special guides can do this as the pallet travels through the system.Pallet dispensing devices for empty pallets allow a system to be fed from a stack of empty pallets. The system can be timed to deliver an empty pallet to the right place for loading at the right moment. A similar concept allows the system to collect and stack pallets as they are emptied.

In some systems, accumulating a group of loaded pallets is necessary to balance the flow of materials. Using electric or pneumatic escapement stops allows one pallet to be released at a time while holding back the rest. This concept can be especially useful to match production requirements further down the line.

Think of what a human being might do with pallet-loaded product on a conveyor line. Someone might measure the load to see if it is too high, too tall or too heavy. Or too light. And, if it doesn’t meet the specifications, route it back to a station for correction. Pallet load conveying systems can do those checks automatically without a person being involved.

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After the first load squaring process; the load is transitioned at a right angle via pneumatic chain transfer. The load enters the second squaring station on CDLR conveyor. The next station downstream from this point is the pallet deflection check.

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If a pallet load is going into an Automated Storage / Retrieval System (ASRS), a loose or broken bottom board on a wood pallet or a protruding nail can cause the load to hang up in the racks. Equipment that can automatically check for loose boards or nails before the load enters the system is available.

At the beginning of this book, we shared with you how pallet load conveying is a niche albeit a very large and varied niche. Selecting the right pallet conveyor system supplier is essential to make the system work properly, for seamless integration with other systems in the facility and to avoid wasted time or excessive labor in the process.

The right conveying system supplier will have the application experience to assist you properly. They will work closely with you on the assessment, planning, and development phases all the way through to the installation, implementation and support phases.

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In evaluating a pallet conveying system supplier, look for those who offer advantages such as:

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✔ A custom engineering capability✔ A proven track record✔ A culture of innovation✔ A discovery process of asking questions and delving into the

most minute details about your system needs before a price is quoted or the first drawing is made

✔ Experience that allows them to bring new ideas to the design process

✔ The ability to adapt to your and your customer’s needs✔ The ability to provide custom equipment at a reasonable cost✔ Excellent project communication and collaboration✔ A diverse product offering

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Partnering with the right conveyor system specialist will continue to bear dividends for you long after the project is complete and signed off.