This article takes an in depth look at plastic pallets.
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Plastic pallets are rigid structures that provide mechanical stability to a bulk quantity of goods during handling to preserve their quality. Handling includes all activities related to lifting, moving from one point to another, stacking, product storage, and long-distance transportation by land or sea. To facilitate the mobility of goods, plastic pallets are designed to be moveable by equipment such as forklifts, pallet jacks, and front loaders.
Generally, pallets can be made from materials such as metal, plastics, wood, and paper. Plastic pallets have many advantages over other materials, such as being lightweight, hygienic, and cost-effective. There are several plastic pallet designs a company may choose from depending on their needs. Plastic pallets can be seen in warehouses, factories, stores, and shipping companies. Nevertheless, all types of pallets remain an important tool in the logistics and supply chain industry.
Plastic pallets have standardized sizes in compliance with the regulations imposed by governing organizations in a certain region. Standardized pallet sizes were made to eliminate wasted time and inconveniences in transferring goods to a particular region. Pallets constructed from other material types are also covered by such regulations.
There are several advantages plastic pallets offer to the supply chain:
This is one of the most important features of plastic pallets in the handling of food, beverage, and pharmaceutical products. Because of its non-porous structure and moisture resistance, plastic pallets reduce the severity of microbial and pathogen growth that can degrade the quality of goods and cause harm to human health.
Plastic pallets are inhospitable to pests and other harmful organisms.
Plastic pallets are exempted from the International Standards for Phytosanitary Measures No. 15, or the "Regulation of wood packaging material in international trade (ISPM-15)." It is a set of measures created by the International Plant Protection Convention (IPPC) aimed to mitigate the introduction and spread of invasive species (e.g., bugs, beetles, and pathogens) through the shipment of insufficiently processed and contaminated wood.
Wooden pallets, as well as other packaging materials like crates and dunnage, are affected by ISPM-15 and are required to undergo the approved treatment process stated in the regulation. Treatment of wooden pallets is supervised by the National Plant Protection Organization (NPPO) of the importing and exporting countries. An IPPC marking (as shown below) is issued to the individual wooden pallets as an identification of their compliance.
Being exempt from this regulation, plastic pallets are not required to undergo such treatments and inspections when entering international ports.
The integrity of plastic pallets remains unaffected when they are exposed to spills, contamination, and moisture. They do not erode easily. Once dirty or contaminated, plastic pallets are easy to clean and sanitize; this prolongs their service life. Hence, plastic pallets are suitable for handling drums and containers containing acids, fuels, solvents, raw meat, dairy products, etc.
Compared to wooden and metal pallets, plastic pallets are easy to handle and move from one point to another because they weigh less. Weight is a major concern during shipping, especially for airfreight shipments. Plastic pallets incur fewer transportation costs in all modes of transportation. They also induce less wear to the shipping vehicles‘ engines in the long run.
Plastic pallets are usually constructed in one solid piece. They have seamless connections between their components because they are produced through the molding process. Their seamless connections eliminate the weak spots present in pallets with mechanical fasteners (e.g., screws, nails) to assemble the pallet. This makes the pallet durable, and it consequently has a long service life.
Plastic pallets last longer than wooden pallets. They can be reused multiple times in the supply chain. They can endure many shipping cycles or long service times in stores, factories, and warehouses before they wear out.
The raw, virgin plastic resins used to manufacture a plastic pallet are mixed with portions of recycled plastics. This is feasible with thermoplastics through another re-molding process. This lowers the production cost and reduces the carbon footprint of the plastic pallet. However, plastic pallets made from 100% virgin plastics have superior characteristics and performance.
A major issue that all companies are confronting in the modern economy and their business practices is sustainability and protection of the environment. Plastic pallets are an ideal solution since they can be designed, manufactured, put to use, end their useful life, and be recycled to raw material, which is used to produce more pallets.
The use of plastic pallets and their ability to be reprocessed and repurposed makes them the ideal tool for shipping and storage as well as a solution to meeting the needs of sustainability.
One of the focuses of any business or manufacturing operation is control, maintenance, and knowledge of their inventory. Bad choices, inaccurate counts, and poor organization can be costly errors and affect the bottom line.
Well aware of the need to monitor and oversee inventory, pallet manufacturers have developed various types of technological advancements that can be attached to pallets for better inventory tracking and include GPS, Io T, and RFID, each of which enhances pallets and makes them more than just a flat piece of plastic to store materials.
There are some disadvantages of plastic pallets:
Plastic pallets are typically constructed from the following materials:
HDPE pallets are the most widely-used plastic pallets because of their versatility, cost-effectiveness, and strength. They have high impact resistance, meaning they absorb shock and retain their stability if they are accidentally dropped or acted on by an immense force during shipping or storage. HDPE pallets have good corrosion and heat resistance and are compatible with most chemicals. However, extensive contact with oxidizing agents and hydrocarbons must be avoided.
PP pallets are the second most widely-used plastic pallets after HDPE pallets. They are more rigid and stronger than HDPE pallets and exceptionally capable of withstanding forklift and pallet jack abuse. They are compatible with most chemicals but are more expensive than HDPE pallets.
PET pallets have good dimensional stability, a high strength-to-weight ratio, and good corrosion resistance. The surface of PET pallets is impenetrable by moisture, liquids, and gases. PET pallets are also highly recyclable.
Polyolefin pallets are low-cost, highly rigid pallets made from a blend of HDPE, PP, and cellulose. However, they are brittle, difficult to mold, and sensitive to moisture. They are considered when they will be used as a one-way (or one-time use) export pallet, or when moisture is not an issue during transportation or storage. A one-way export pallet is a pallet that will not be returned once it is sent for shipment.
Fiberglass pallets are strong, durable, and impact-resistant. They are inherently resistant to fires and have fire-retardant properties, making them superior to wooden and paper pallets. However, fiberglass pallets are more expensive.
Plastic pallets can be produced by a variety of manufacturing processes (e.g., molding, extrusion). These processes produce durable and robust plastic pallets. In the case of recycling, the used plastics undergo pre-treatment (e.g., cleaning, drying, and size reduction) before combination with the virgin resins.
Injection molding involves the high-pressure transfer of molten plastic material into the mold where it solidifies and cools. The molten plastic occupies the volume of the mold cavities where it acquires the shape of the pallet. Injection molding is capable of producing pallets with intricate details.
The process of thermoforming involves heating plastic sheets to their forming temperature and stretching or pressing them over a mold such that the heated plastic takes the shape of the mold. The tooling for thermoforming is less expensive than injection molding. The overall cost of the process varies depending on the color of the pallets and how the raw material is blended. Thermoformed pallets, especially those that are twin-sheet thermoformed, are durable. Nestable plastic pallets were developed from the thermoforming process.
Structural foam molding is a low-pressure injection molding that involves feeding an inert gas to the molten plastic to decrease the density and ultimately the weight of the plastic pallet.
The molten plastic fed into the mold has a volume less than that of the cavity. Once the inert gas expands inside the mold cavity, it creates a foaming reaction with the molten plastic. The inert gas is also responsible for supplying the holding and final packing pressure. The resulting plastic pallet has a cellular structure in its core, but the walls remain dense. The produced plastic pallets have a high strength-to-weight ratio and high impact resistance.
Structural foam molding is cheaper than high-pressure injection molding because it does not require high pressure or a steel mold; the mold can be made from lighter and less expensive materials such as aluminum.
Rotational molding (or rotomolding) involves simultaneous heating of powdered plastic material contained in a hollow mold and slow rotation on two axes. As the plastic is heated, it melts and adheres to the inner walls of the mold and consequently takes its shape. After the molten plastic is settled on the inner walls, it is cooled to solidify and then taken out of the hollow mold.
Rotomolded pallets have uniform wall thickness on all sides, edges, and corners. This increases the pallet strength and integrity. This process is also economical because of its inexpensive tooling and lack of scrap from excess plastic materials (e.g., flashes, fillings from runners and sprues).
A blow molding process uses compressed air to stretch a heated plastic across the interior walls of the mold cavity. Blow-molded pallets also have uniform wall thickness and higher load capacity. They also have higher strength and impact resistance than injection-molded pallets.
The process of blow molding involves the creation of a parison that is cut to the length required for the pallet. Once processed, the parison is blown into the mold cavity that has the shape and configuration of the pallet. The parison is inflated by high pressure air that forces it against the walls of the mold to produce an even thick surface on the interior of the mold. After the pallet cools and is completely formed, it is released from the mold for secondary finishing such as machining and trimming.
Many of the physical and performance properties of blow molded pallets are similar to twin walled thermoformed pallets. Load capacity for blow molded pallets varies between 6 to 10 metric tons with a dynamic range of 2 to 3 tons. The strength and weight capacity of blow molded pallets is related to the ability to control the uniform wall thickness during processing.
In profile extrusion, the individual pallet parts are produced by forcing the molten plastic through an extruder; then the parts are fastened together by nails, screws, heat, weld, or glue. The extruded plastic pallet resembles the structure of a wooden pallet. The incorporation of fasteners lessens its durability.
The compression molding process uses heat and pressure to cross link the various agents in the plastic resin. An essential part of the process is a thermosetting resin, known as a slug, which is placed between two mold halves. To avoid waste, and increase accuracy, the slug is weighed and precision measured prior to being placed between the die halves.
The mold halves move together at pressures between 800 psi to 2000 psi until the proper mold temperature is reached. The use of appropriate temperature and pressure ensures that the proper crosslinks are formed in the resin. When the mold is opened, the pallet is ejected while it is hot since a cooling cycle is not necessary in the compression mold process.
Plastic pallets may be grouped according to the mode of supporting the top deck of the pallet:
In stringer pallets, the top deck is supported by parallel, longitudinal slabs, called stringers, that are positioned in opposite edges and across the center of the pallet.
In block pallets, the top deck is supported by columnar posts, called blocks, that are positioned in the corners, in the centers of each edge, and at the center of the pallet itself.
Plastic pallets may be classified according to the number of entry points. The entry points are the areas wherein "forks" of the forklift or a pallet jack can be stuck to lift or move the pallet.
Four-way pallets allow entry on each side of the pallet. They provide more handling efficiency (e.g., less load and unloading time), especially when the floor space is small because all sides are accessible by the handling equipment. Generally, all block pallets are four-way pallets.
Two-way pallets only allow entry on two sides of the pallet, and they are opposite sides. Since the entry points are limited, the handling equipment is required to maneuver to a specific angle to gain access to the pallet. To be accessed by the handling equipment, these pallets must be stored at a specific orientation that exposes the entry points.
All non-modified stringer pallets are two-way pallets. Conversion of a two-way pallet into a four-way pallet involves the creation of notches; this can be easily done in wooden stringer pallets but is not feasible in plastic pallets. This conversion reduces the strength and load capacity of two-way pallets.
Plastic pallets can also be distinguished according to their deck design and configuration:
Skids and pallets are often used interchangeably. All pallets with no bottom deck are called skids. Plastic skids are lighter in weight. The absence of its bottom deck increases their mobility and makes them easier to slide.
Open-deck plastic pallets have "ventilations" or mesh-like perforations in the top deck. The openings in the top deck allow easy drainage of wet products being carried. The openings also make the pallets lighter in weight and less expensive.
Closed-deck (or solid deck) pallets have no openings in their top deck. The top deck may have an anti-slip surface to prevent the sliding of products. Since there are no hard-to-reach areas created from the openings, closed-deck plastic pallets can be easily cleaned and are suitable for small items.
Double-face plastic pallets have two solid decks at the top and bottom of the pallet. This is different from the open and closed-deck pallets, which have an open bottom. The load carried by the pallet is also distributed to the bottom deck; this makes the pallet durable. A double-face pallet may be a reversible or non-reversible pallet:
Have identical designs on their top and bottom decks. Products are stackable on either side of the pallet.
Have different top and bottom decks and weigh less than reversible pallets. The top deck has more plastic material to support the product when it is mounted on the pallet.
Double-wing plastic pallets have top and/or bottom deck that extend beyond the surface of the stringers or blocks, creating more space for the products.
Lastly, there are special types of plastic pallets that have useful features to improve convenience and ergonomics when handling them. These special types of pallets are:
Drum pallets are used to hold drums and containers filled with oil, chemicals, and other liquid substances during transportation and storage. The drum fits in a customized recessed ring in the top deck built to hold it in place; other drum pallets may not have these recessed rings. Drum pallets may also be designed to have a catch panel to contain spills and leaks and prevent them from spreading further.
Stackable pallets have solid bottom support that gives stability to the products loaded on top of them when they are placed on top of another loaded pallet. They are commonly used in warehouses to stack goods efficiently and to save floor space.
Nestable pallets have hollow legs on their corners to enable stacking of empty pallets when they are not loaded. Unlike stackable pallets, they have an open bottom deck. Nestable pallets free up space during return trips from shipping and in warehouses when these pallets are not in use.
Rackable pallets are injection molded, rotationally molded, or foam molded and are heavy duty pallets with significantly higher load capacity. The different types of rackable pallets are designed to meet the needs of different storage racks.
Full frame rackable pallets have six runners on the bottom to give them greater support and structure. Three runner rackable pallets are designed to be placed on racks such that the runners are perpendicular to the beams of the rack.
Generally, pallet sizes of all types are standardized to improve supply chain efficiency. Standardized pallet sizes eliminate the difficulties in the handling and transporting of goods performed by various groups and companies. Several organizations and associations regulate the sizing of shipping pallets. The most popular among them are:
ISO Pallet Sizes Many pallet sizes exist around the world. However, the ISO approves six, which are adopted from commonly used pallet sizes in different regions. This specification is detailed in the ISO Standard 6780:2003 Flat Pallets for Intercontinental Materials Handling – Principal Dimensions and Tolerances.
| Dimensions in mm (W x L) | Dimensions in inches (W x L) | Regions most used in |
|---|---|---|
| 1016 x 1219 | 40 x 48 | North America |
| 1000 x 2000 | 39.37 x 47.24 | Europe, Asia |
| 1165 x 1165 | 45.9 x 45.9 | Australia |
| 1067 x 1067 | 42 x 42 | North America, Europe, Asia |
| 1100 x 1100 | 43.3 x 43.3 | Asia |
| 800 x 1200 | 31.5 x 47.24 | Europe |
Grocery Manufacturers Association (GMA) Pallet Sizes The GMA is the national trade association that helps in the mobilization of packaged consumer goods in the United States of America. GMA lists twelve pallet grades and their dimensions and specifications. Each pallet grade is assigned to a specific industry.
| Dimensions in mm (W x L) | Dimensions in inches (W x L) | Production Rank | Industry |
|---|---|---|---|
| 1016 x 1219 | 40 x 48 | 1 | Grocery, many others |
| 1067 x 1067 | 42 x 42 | 2 | Telecommunications, Paint |
| 1219 x 1219 | 48 x 48 | 3 | Drums |
| 1219 x 1016 | 42 x 42 | 4 | Military, Cement |
| 1219 x 1067 | 48 x 42 | 5 | Chemical, Beverage |
| 1016 x 1016 | 40 x 40 | 6 | Dairy |
| 1219 x 1143 | 48 x 45 | 7 | Automotive |
| 1118 x 1118 | 44 x 44 | 8 | Drums, Chemical |
| 914 x 914 | 36 x 36 | 9 | Beverage |
| 1219 x 914 | 48 x 36 | 10 | Beverage, Shingles, Packaged Paper |
| 889 x 1156 | 35 x 45.5 | Unknown | Military ½ ISO container, fits 36" standard doors |
| 1219 x 508 | 48 x 20 | Unknown | Retail |
European Pallet Union (EPAL) Pallet Sizes EPAL pallet sizes, or EUR pallets, are the standard pallet sizes in Europe. All EUR pallets contain either the EUR logo or initials such as DB and EPAL.
| Euro Pallet Type | Dimensions (W x L x D) | ISO Alternative |
|---|---|---|
| EUR 1 or EUR | 800 mm × 1200 mm, 31.50 in × 47.24 in | ISO 1 |
| EUR 2 | 1200 mm × 1000 mm, 47.24 in × 39.37 in | ISO 2 |
| EUR 3 | 1000 mm × 1200 mm, 39.37 in × 47.24 in | |
| EUR 6 | 800 mm × 600 mm, 31.50 in × 23.62 in | ISO 0, half the size of EUR |
| 600 mm × 400 mm, 23.62 in × 15.75 in | quarter the size of EUR | |
| 400 mm × 300 mm, 15.75 in × 11.81 in | one-eighth the size of EUR |
Some pallet sizes listed by the GMA and the EPAL have counterparts in the ISO-approved pallet sizes.
Before choosing which plastic pallet size to acquire, it is critical to determine the region where it will be utilized. For instance, if a pallet will be used for the shipment of goods to a particular region, the shipping company must use a pallet size that is accepted in the region of the destination. Failure to do so can result in additional costs (due to the need to acquire the correct pallet) and delays in product delivery. In addition to geographical compliance, it is important to consider the application of the plastic pallet before selecting a size.
The load capacity of plastic pallets is dependent on three forms of capacity ratings, which are dynamic, static, and racking. Over the years, it has been assumed that plastic pallets have a lower load capacity than wood pallets. The inaccuracy of such an assumption is due to the many varieties of plastic pallets, each of which has a different load capacity.
Dynamic load capacity is the maximum weight a pallet can hold when in motion.
Static load capacity is the amount of weight a plastic pallet can hold when it is immobile, positioned, and not moving.
Racking load capacity is the maximum weight a pallet can hold in a racking system, where the center or edges of the pallet are unsupported.
The load capacity of a pallet is based on the assumption that the weight placed on the pallet is evenly distributed. For the best calculations of load capacity, the actual weight load should be lower than the presumed weight capacity.
In most cases, determining the load capacity of a wood pallet is rather straightforward since most wood pallets are made from the same types of wood. The many varieties of plastics makes the determination of a plastic pallet's load capacity more challenging due to the fact that each type of plastic has distinctly different capabilities, properties, and characteristics. Depending various design parameters, plastic pallets have a greater load capacity than wood.
Some of the factors that determine the load capacity of plastic pallets are the types of plastic material and work environment. In regard to plastic material, virgin plastics are stronger and more durable than recycled plastics and are capable of holding more weight. Polypropylene and high density polyethylene have the highest load capacity.
Polypropylene and high density polyethylene are resistant to most chemicals. The main factor that influences the weight capacity of plastic pallets is temperature where extreme temperatures affect their performance and load capacity.
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