Overview of RFID
As anyone involved in supply chain management is aware, the impetus to adopt and incorporate radio frequency identification (RFID) technologies throughout all levels has arrived.
The supply chain is a global, multi-level concept that covers all aspects of taking a product from raw materials to a final product and then shipping it to a final point of sale.
RFID is a generic term for technologies that use radio waves to automatically identify individual items. In the supply chain, this can refer to any or all of the following: the product itself, the product package, a pallet or transport unit, and-or larger freight containers.
The typical RFID system includes small tags that are attached to an item (product, package, pallet, or container) and an interrogator (reader-writer). The tags contain a transponder with a digital memory chip that has a unique numeric identification code. An interrogator has an antenna with a receiver and decoder that activates the RFID tag so the interrogator can read the tag and sometimes write data to the tag.
Information stored on the tag can include identification, location, or product specifics, such as price, color, date of purchase, etc. Tags can be powered by an internal battery (active tags) or from the field, generated by the interrogator (passive tags).
Passive tags are small, lightweight, and long-lasting (unlimited operational lifetime), but they are constrained in their ability to store and transmit data (read only). Figure 1 depicts several variations of typical passive RFID tags. Active tags are larger, more sophisticated read-write devices with a life expectancy that varies with temperature environments, read-write cycles, and usage.
The driving forces toward adopting RFID technologies are the potential cost savings and revenue generating benefits that can be achieved between manufacturers and their suppliers and between manufacturers and retailers.
The benefits are simple — more efficient tracking of materials, components, sub-assemblies, and finished goods in production and in transit. This leads to time saving reductions in errors in
receiving and tracking inventory, reductions in revenue depleting problems like stock-outs, and elimination of lost sales due to items that are in stock but cannot be located.
The use of RFID tags ultimately will streamline the global supply chain by improving the speed, accuracy, and productivity of operations associated with it. Already two market giants, Wal-Mart and the Department of Defense, have mandated RFID compliance dates to their suppliers.
Although the adoption of RFID technologies promises many benefits, widespread adoption will not occur without overcoming many challenges and obstacles. The most obvious among these are the costs and limitations regarding tag and reader technology. Currently passive tags are still expensive, costing around 50 cents each, making them impractical for tagging the millions of items that cost only a few dollars. Active tags cost far more, with readers typically costing $1,000 or more, and companies needing hundreds — if not thousands — of readers to cover all their factories, warehouses, and stores. Furthermore, the readability range of readers is only about 3 to 5 feet for passive tags and only slightly longer for active tags. This implies great limitations in accessing tag information during storage and shipping. Nonetheless, purchasing powers like Wal-Mart and the Department of Defense exert tremendous influence on the speed and scope of RFID implementation.
Standards Will Aid Pallet Suppliers
The role of the pallet within the supply chain application of RFID tags remains unclear. Current information available to pallet suppliers does not clearly define whether tags will be placed on the pallet and, if so, how this will be accomplished.
An effort within the International
Organization of Standardization (ISO) may begin to provide guidance to pallet suppliers and their customers. Standards can help to demystify a process and provide a sound, organized basis for adopting technologies such as radio frequency identification.
An ISO joint working group has been formed to standardize RFID applications to the supply chain. The chairman of this joint working group is Craig Harmon, an internationally recognized expert on RFID technology. Dr. Marshall (Mark) White, director of the Virginia Tech Center for Unit Load Design, is the official liaison to the joint working group for the ISO technical committee on pallets. The joint working group is drafting five standards corresponding to the five layers within the supply chain where RFID technology is applicable. These five draft standards are:
• ISO 17363, Supply chain applications of RFID – freight containers
• ISO 17364, Supply chain applications of RFID – returnable transport items
• ISO 17365, Supply chain applications of RFID – transport units
• ISO 17366, Supply chain applications of RFID – product packaging
• ISO 17367, Supply chain applications of RFID – product tagging
The format of each is similar: they contain guidance for data to be placed on the tag, discuss functional frequencies, and provide data regarding tag performance. This latter topic is of most interest to pallet suppliers.
These standards describe the application of two tags — the EPC tag and a generic tag. Of the five documents, pallets are included in the scope of two. The two draft standards (supply chain layers) of RFID applications that apply to pallets are ISO 17364 – returnable transport items, and ISO 17365 – transport units.
ISO 17364 defines returnable transport items (RTI) as all items used to assemble goods for transportation, storage, handling, and product protection in the supply chain that may or may not
be returned for further usage. Examples include pallets with and without cash deposits, as well as all forms of reusable crates, trays, boxes, roll pallets, barrels, trolleys, pallet collars, and lids. In this category, the title or ownership of the pallet or container is not transferred
as the pallets are managed within pools. The RFID tag can include information regarding the RTI and its content.
This standard would apply to the CHEP system.
ISO 17365 defines transport units as a transport package, pallet, or a unit load. Characteristics unique to transport units are that they allow grouping suitable (packaged) products for more efficient and effective transportation and distribution. In this level of the supply chain, title or ownership will be transferred, such as in the case of the so-called ‘white’ pallet. The tag on the unit will contain information regarding contents, not the pallet or unit load itself.
Key specifics of interest to pallet manufacturers, addressed in the draft standards, relate to tag operation, location, and presentation. First, the ISO draft standards recognize that a wide range of materials utilized in primary packaging and in small and large transport units may interfere with RFID equipment. Nonetheless, the standards detail specific requirements to ensure effective RFID tag and reader function and serviceability. For example, RFID tags should function properly from -40oC to +80oC and, for shorter periods of time, harsher temperatures ranging from -50oC to +100oC. They should be able to endure exposure to rain, dust, UV, and other weather conditions while lasting throughout the lifetime of the RTI or transport unit.
To minimize or prevent damage, RFID tags must be recessed on the outside or inside of the RTI or transport unit. The tag proximity to metal parts must be maximized to reduce the disturbance of the RF-signal while moisture from wood or the product itself may interfere with tag operation.
Implications for Pallet Suppliers
The development of these ISO draft standards is still in the early stages and may change before final adoption. Unfortunately, these documents do not give us guidance as to what extent RFID tags will be applied to the pallet versus other locations on the unit load. However, the Department of Defense has been interested in the application of tags to pallets and has conducted limited trials.
To the extent that tags may be present on pallets, some directions are clear. For non-returnable transport units, i.e. white pallets, pallet suppliers will not likely apply the tag since unique identification codes on the tag will be controlled by the owner of the pallet. To do this the pallet customer will likely apply a passive tag in a so called ‘slap and ship’ environment. The responsibility for tag applications to returnable transport items or pallets is less clear but will likely still be the owner of the pallet or container.
The American Society of Testing and Materials (ASTM) is drafting standard test procedures for measuring the readability of tags on packaging.
Pallet recyclers will have to remove and recycle some tags from many pallets they receive with tags attached. Recycling and destruction of tags will have to be controlled to maintain data security and minimize environmental impacts; therefore, tag design and application should consider the recycling process of pallets.
Nails in wood pallets should not measurably interfere with radio signals because interrogators and readers will not scan the regions of pallet that contain exposed nail heads. Embedded nail shanks should not interfere with the signal either; however, metal connector repair plates on scanned surfaces pose a potential problem. Green wood pallets will have to be dried either before tag application and use or the wood surface will have to be modified to minimize the effect of moisture on tag attachment and interrogator and/or reader operation. To improve RFID tag reliability, placement of tags on wood pallets should minimize the exposure of the fragile tags to impacts by materials handling equipment.
Recent research conducted at Virginia Tech titled, ‘Topographical Mapping of the Mechanical Stresses on Wood Pallets During Use,’ documents that the location on a notched stringer-style pallet least likely to sustain damage from fork tines is on the outside edge of the outside stringer and between the notches. However, these same surfaces are subject to impacts or contacts between unit loads during close quarter handling when warehousing and-or loading and unloading trailers or freight containers. Therefore, the tag should be recessed in the location between notches.
‘RFID Ready’ Pallet
Using the results from the research discussed above and the guidance for tag operation in the draft ISO standards, a group of packaging science students at Virginia Tech, in cooperation with a local pallet supplier, developed an ‘RFID ready’ pallet concept (Figure 2).
Key components of this concept include low cost, recessed tags applied to a modified surface that can prevent moisture effects, and a placement location on the pallet that will minimize the potential for in-use damages.
Conceptually, the region of a stringer between the notches is embossed (compressed) to a depth of approximately 1/16-inch. This has no effect on pallet strength and is a low cost process. A polyurea coating is applied to the embossed area for moisture protection and tag attachment.
Embossing must be applied to both sides of all stringers unless the selection of stringers designated for RFID application can be controlled. The coating should be applied after pallet assembly to minimize cost.
This RFID concept will soon be tested in an RFID interrogator system being installed at the Center for Unit Load Design at Virginia Tech.
RFID application to pallets will be a business opportunity for pallet suppliers and recyclers. The pallet industry should continue to carefully monitor new developments of this new technology.
