Pallets: Where Form Meets Function

As the saying goes, Pallets move the world.

It would be hard to find a company today that does not use pallets. Pallets are the direct link between packaged products and the material handling environment. Moreover, they are the critical link to supply chain performance and efficiency. Unfortunately, pallets are also the least understood and most overlooked components within the supply chain. The purpose of this article is to provide an overview of the pallet industry, the basic performance parameters that are necessary to optimize pallet design, and current design and material options.

Todays Pallet Industry
There are more than 450 million new pallets produced in the United States each year. Close to 1.9 billion are in use on a daily basis. The 48x40 grocery (GMA) pallet is the most common pallet size in the U.S., and represents about 30% of the pallets produced each year. The top 10 most common U.S. pallet sizes represent about 60% of the annual pallet production. The remaining 40% of the market includes hundreds of sizes that are specially tailored to specific customer needs. Although we live in an increasingly global community, pallet sizes vary significantly between different regions of the world. Internationally, there are 6 pallet footprints (sizes) recognized by ISO. There are trends, however, towards increasing domestic and global pallet size standardization.

There are five basic interactive parameters that determine pallet suitability for a given application: strength, stiffness, durability, functionality, and purchase price. These parameters are extremely interdependent, and optimizing just one (i.e. minimizing price) will necessarily impact the others. While the balance among these five parameters will vary, depending on the specific product and distribution environments, they all apply regardless of the pallet design or material used.

Pallet Materials
Many products experience material conversions over time as innovations occur or markets change. Pallets are an exception to this trend. The pallet material of choice over the past 70 years has been, and still is, solid wood. This is unusual for a commodity product. Pallet users today face a wide variety of material and design choices, but wood pallets still comprise 90-95% of the US marketand this is not likely to change in the future. Pallets made from other materials are important and the market will respond to trends such as standardization, improved retrieval operations, more reusable pallets, and pest regulations. Below are the primary pallet material choices and a brief discussion of each.

Wood Pallets
Wood pallets are by far most common because they represent a good balance of the five design parameters discussed abovethey are strong, stiff, relatively durable, and inexpensive. Because wood pallets have been around so long, many packaging and material handling systems are built around the use and performance of wood pallets. Furthermore, wood pallets are easy to prototype using a computer aided design program called PDS that estimates pallet strength, stiffness, and service life. This program is available for wood pallets only. Wood pallets are also easy to repair. In recent years, the pallet repair and remanufacturing industry has grown to accommodate approximately 233 million pallets per year. Some disadvantages of wood pallets are that they have metal fasteners (nails) that can potentially damage products. Wood pallets can also have splinters, moisture related problems, bugs, and sometimes significant performance variation between pallets.

Plastic Pallets
It is estimated that plastic pallets make up 2-4% of new pallet production in the US, or 15 million new plastic pallets per year. Plastic pallets cost anywhere from 3 to 6 times as much as wood pallets. The most common plastic materials for pallets are HDPE, PP, and PVC. The most common manufacturing process is structural foam molding, but other processes include injection molding, profile extrusion, rotational molding, compression molding, and thermoforming. General advantages of plastic pallets are high durability, cleanliness, no metal fasteners, bug free, weather resistance, and flexible design potential. Disadvantages include higher price, difficulty to prototype, low friction, low stiffness, lack of repair options, and fire safety ratings.

Plastic pallets are most common in captive or closed loop warehouse environments supporting 2000 pounds or less. The automotive, dairy, pharmaceutical, USPS, and beverage industries commonly use plastic pallets. In Japan and other Asian countries, it is estimated that plastic pallets make up 50% or more of the reusable pallet pools.

Composite Wood Pallets
Wood composites, such as plywood, OSB, particle board, and laminated veneer lumber, represent 2-4% of the pallet market. Beer pallets were a historical market for composite pallets. More recently, due to the implementation of international pest regulations that apply to pallets made of solid wood, composites pallets have become a desirable alternative for import/export use. Composites are exempt from pest regulations and often have a lower price than plastic or metal pallets. Wood composite pallets are also durable, dry, provide complete pallet deck coverage, and are easy to prototype (they can also be designed using PDS). Some disadvantages are that they cost more than solid wood, are expensive to repair, less weather resistant than plastic or metal, and still require fasteners.

Paper Based Pallets
Paper pallets represent less than 1% of the market, and include corrugated, honeycomb, solid fiberboard, and molded pulp. In the case of containers, there has been dramatic shift over the years from wood to corrugated paperboard. This has not been the case for pallets. While a corrugated box is less expensive than a wood box, a paper pallet costs more than the equivalent wood pallet. Paper pallets mainly find acceptance within niche markets with light loads. Recently, new markets have opened, driven mostly by international pest regulations and increased airfreight shipping with weight-based charges. The key advantages of paper pallets are that they are lightweight, easily recyclable, have a smooth deck surface, and are dry and bug free. Disadvantages include a price higher than wood, susceptibility to moisture, lack of stiffness with flexible loads, low durability, and low product protection.

Metal Pallets
Metal pallets make up less than 1% of the market. Materials include carbon steel, stainless steel, and aluminum. Of these, carbon steel offers excellent durability at the lowest cost. Stainless steel doesnt require a paint coating, and is preferred for such applications as clean room environments. Aluminum offers the durability of metal at a lighter weight. Carbon steel units are relatively expensive compared to wood, and stainless and aluminum cost about 2-3 times that of carbon steel. Long term costs, however, can be lower than wood. General advantages of metal pallets are high strength and stiffness, excellent durability, bug free, no splinters, sanitary, and recyclable. Disadvantages include a higher initial price, significant weight, low friction, and susceptibility to rusting (carbon steel). Metal is primarily used in captive or closed loop environments where durability and product protection are key performance requirements. Metal units today are increasingly price competitive and lighter in weight. Primary industries that use metal pallets include automotive, pharmaceutical, lawn tractors, motorcycles, and tires.