Pallet Tracking With RFID

The day had started off in less than fantastic form for Johan Anderson. At breakfast, he had somehow managed to consume two heaping teaspoons of cereal soaked in long expired milk before realizing it, and his stomach was now beginning to feel the after-effects of this unfortunate mistake. His head was much more concerned with the crippling abdominal spasms he was experiencing than with the cargo being loaded into the back of his delivery truck. Fortunately whether Johan does or doesn't manage to remember what his cargo is, or how much of it he has, matters not. Neatly stacked in the back of his truck are 100 plastic pallets. This particular shipment contains new pallets whose lives will consist of being repeatedly filled and emptied with an array of crates housing vegetables and other fresh produce. This cycle will continue until the pallets are again recycled to the basic elements from which they were derived.

But be certain, these are not your ordinary pallets. These are smart pallets with RFID tags embedded in their construction.

Arca System, Perstorp is a manufacturer of reusable plastic pallets. Svenska Retursystem (SRS) distributes over 1 million of these pallets throughout Sweden. With such a large number of pallets in circulation, keeping track of each pallet is a formidable task. Deposits for each pallet are required to cover costs should they be damaged or lost. SRS was constantly running into problems where pallets were being returned later than expected, or not at all. The outdated inventory system wasn't adequately keeping track of where pallets were being lost or damaged resulting in SRS incurring the costs. A system for tracking the pallets while they were out in circulation was desperately needed.

There were several proposed solutions to this problem. Bar code was the first technology considered. However in this application bar code was determined to be insufficient due to a variety of problems. First because these pallets are for carrying fresh produce, cleanliness standards are crucial to maintain. In order to do this each pallet re-entering the facility is treated with a variety of cleaning chemicals and high-pressure washing. Bar codes could simply not endure these conditions. Also, the life of any pallet inevitably involves a significant amount of bumping and bruising, and even a small scratch can render a barcode useless.

Jan-Erik Nilsson, President of EMS RFID AB (a Swedish distributor of Escort Memory Systems technology), proposed a solution using 13.56MHz RFID. The solution provided real-time visibility of all pallets in circulation. The basic benefit of using RFID would be that each pallet could be outfitted with a tag that could remain with the pallet for its entire lifetime. EMS RFID technology was chosen in this application for a number of reasons. Most notably EMS' LRP-P3858 tags are some of the most resilient tags available today, and can survive the harsh conditions application requirements called for. Instead of mounting these tags to the exterior of the pallet, engineers embed the tags in the interior structure of the 2-piece pallet. Two tags are embedded inside opposite corners of the pallets, in order to assure that regardless of orientation on the conveyer, one tag will be picked up. Once installed the tags can be continuously written to with information and read by the antenna. Once pallets are returned the tags are cleared, then written to again.

EMS' LRP820-08 plate antennas were used in this application to read the LRP-P3858 tags. Two LRP820-08 antennas were installed at the entrance to the pallet-cleaning machine at SRS. Pallet history is downloaded for each pallet, and if damage is evident the proper customer is charged. Likewise, pallets whose origin is unknown can be determined by reading the tags inside.

Pallets out on the Road
Pallets leave SRS and arrive at the warehousing hub of a major supermarket. Supermarket operators can use a portable hand-held scanner to read and write to the tag with a time and date stamp, as well as handling directions. The pallets are then loaded up with perishable foods, and the tags are written to with produce info such as expiration date and storage instructions. The full pallets are then delivered to the neighborhood grocery store where grocery workers scan each pallet as it arrives to ensure freshness, and quality has been maintained. After their job has been completed, empty pallets are loaded into the trucks and returned to SRS where they are again read. After any relevant charges are processed, pallet information is then cleared, and the tag is written to with date/time information for its next voyage out into the world.

Results of the RFID system were impressive. Each pallet has a self-contained record keeping system, eliminating the excess paperwork that is common with pallet shipments. The combination of resilient RFID tags and re-useable pallets is a cost effective solution; wooden pallets and bar code labels are both consumables while Plastic Pallets and RFID tags are recycled, and reused.

The advantages of the resulting RFID system are far reaching. By accessing the shipment history of each incoming pallet, SRS is able to recoup for lost and damaged pallets by having record of who was responsible for the product at any given time. Because Customers pay for the length of time they have the pallets as well, usage costs can be immediately determined and passed onto customers. Theft, also a rampant problem, is greatly reduced with RFID. If a stolen pallet re-enters the facility, by reading the tag, operators can determine when and where the pallet was taken from. Customers, who thought they would surely be charged for the lost pallet, are relieved to know that the pallet has been located, and their account credited for its return.