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July 24 2006 03:51 PM

The more things change, the more they stay the same. That old adage is as true as ever, even in today's ever-changing economy. As industries enter the 21st century, the management of human and material resources is still a top priority. And it remains as big a challenge as it was 100 years ago, at the height of the industrial revolution.


How many times has your warehouse pulled its workforce off their regular assignments to look for a misplaced piece of material? Work on all other projects comes to a screeching halt. Finally, all too often, the production side ends up duplicating the asset, so it may be shipped as planned. Now you have an extra product still not located, with an unknown shelf-life and substantial time and money lost in the process.


Similar problems arise in the fulfillment of orders. In many pick-and-pack operations, completed orders are loaded on a dolly along with other orders, which may be headed to different regions of the country. As the pick ticket arrives for Invoice #1, the dolly is located and moved to the corresponding loading bay. About the same time, the pick ticket for Invoice #2 is processed.


Then, the unexpected happens: the original dolly cannot be found. Again, everything stops, while employees search for the dolly. However, they cannot find it. The department has to halt production even longer while they rebuild the existing invoice. What do they end up with? Expensive downtime of personnel and machinery as well as a duplicate custom build. The product now must be sold at a reduced margin thereby lowering profits.


All companies, regardless of size, deal with the issues of capital inventory location, pre-staging of inventory as well as overall warehousing/distribution requirements. One company operating a 50,000 square-foot building housing both manufacturing and shipping estimates they are losing one person per shift due to the inability to locate assets in a timely manner. As a three-shift operation, that translates into $75,000 in personnel costs alone.  This figure does not include the costs of producing and storing extra product when the asset is rebuilt nor the revenue lost since it must now must be sold at a reduced rate.


Fortunately, a number of tools are now available to plant managers to avoid this nightmare and help streamline asset management. Radio Frequency Identification (RFID) and Real Time Location Systems (RTLS) are two emerging technologies that are starting to have a significant impact on the way we control, manage, deliver, develop and move inventory throughout the supply chain all the way down to the end users.



Radio Frequency Identification is an electronic barcode attached to the particular stock, tool, equipment or anything you want to be able to track. RFID uses two types of tags: active and passive.  Both have advantages if they are used in the proper environment. Each tag has a unique identification number, which is then associated with an asset.


Passive tags have no battery and, therefore, require a reader to be in close proximity to identify both their location and stored information. These identification tags are unobtrusive and have a much lower price tag than active tags ranging from a couple of cents to a few dollars depending on the bells and whistles the user might want.


Active tags are battery-powered devices. Most sit silent until queried by a reader device but some send out a signal at consistent intervals. These tags are larger than passive tags (about the size of a nine-volt battery) and are more expensive, with prices starting at $20. Their advantage is they can be read at a greater distance, up to 300 feet, using some current technologies.


Active and passive tags both must overcome some application obstacles. Typical problems are radio frequency noise, the orientation of the tag in relationship to the reader, the number of tags, the area of the facility (indoors versus outdoors) as well as the discipline/ability of the personnel working with the tagged asset. All of these factors influence the success of the operation of the RFID system. 


Real Time Location Systems

Real Time Location Systems are active tags whose position can be accurately determined through either triangulation or attenuation. RTLS allows a tagged item to be tracked throughout a warehouse or manufacturing facility, no matter how large and busy. It does have some limitations: because RF is subject to deflection and absorption of signals, tracking accuracy in a real-world environment is limited to 10 to 15 feet. But this problem can be alleviated with handheld devices to supplement ceiling-mounted reader units.


RFID/RTLS as Management Tools

RFID and RTLS can become powerful management tools in controlling production, inventory and fulfillment costs. Tagging the manufactured item can generate a production "information base." Should it really take one full day to build a tractor? Maybe sections four and five in the process are slower than they should be because of poor tool or material planning. If tools are tagged and tracked, however, you may discover the tractor can be built in three-quarters of a day. Over an annual timeline, you'll end up with a lot more tractors produced.


Inventory decisions that are based on flow control can be made from real-time, highly accurate information. Even if pallets are misplaced in the warehouse, their location can be immediately determined. The "lost dolly" scenario described earlier becomes a thing of the past.  Tag the dollies and the order placed on each one. This information stream flows wirelessly from the tag to information base. It is always in an updated mode, so fulfillment personnel accessing the information can locate and walk directly to the requested inventory.


RFID tags can be cross-referenced with shipping manifests to ensure 100% order accuracy a very basic, but often elusive, goal for increased customer satisfaction. As margins continue to tighten and goods become more consistent among competitors, getting the right product to the customer at the right time will create repeat business, regardless of where one stands in the supply chain.

Most users want specific information from the tagged assets, so the RFID/RTLS system must be customized at installation. This issue is best dealt with through the use of appropriate software.  Of course, it is important to remember that the more human interaction, especially in entering data into the information base, the higher the margin of error. In some cases, this error margin can be as high as 40 %. Its best to allow only certain individuals to input data. On the other hand, its essential to give employees easy access to the location and description of the requested inventory.


Wireless and Web Applications

RFID/RTLS technologies now collaborate successfully with some wireless backbones. A handheld RFID reader in the production line, or on the warehouse floor, instantly transmits information to an online database. This greatly reduces labor and hardware (data and power cabling) costs.


There is a growing demand for ability to access the RFID/RTLS information base through the Internet. Managers who want to see the inventory as it's flowing in real time are often at home, across the country or on the other side of the world. Being able to change flows, purchase goods or reprioritize inventory on the fly becomes critical for companies trying to stay one step ahead of the competition.


An RFID/RTLS wireless data link configuration is shown here. The Ethernet cable is connected between the Ethernet interface and also the Ethernet port on the host computer. If the Ethernet adapter is connected through an Ethernet hub, use the crossover cable. A DB-9 serial cable and a null modem adapter are connected between each reader and the serial adapter.


RFID/RTLS is not a perfect science. In fact, it seems to be a little bit science and a little bit black magic. Does it have flaws? Yes. Will it benefit your plants effectiveness in managing personnel and materials?  Again, yes. RFID is a growing technology that is being developed and advanced on a daily basis. Its ability to control, streamline and fine-tune production and inventory can help industries bridge the gap from database to information base to maximize resources, while creating fewer headaches for the humans involved.


Dan Melton is a project supervisor with Wireless Mountain Labs, Inc., in San Luis Obispo, California. He may be contacted at 805-596-0960 ext. 215 or e-mail