The Traceability Wars

沃尔玛和国防部的我nventory management and product traceability hot topics these days. Since deciding to automate these tasks with radio-frequency identification (RFID), they have demanded that their suppliers adopt the technology and use RFID tags to trace all deliveries. When organizations with their clout issue such mandates, even the biggest companies take note—and respond.

Dallas-based Kimberly-Clark Corp., for example, is integrating RFID technology into the enterprise resource planning (ERP) system that tracks deliveries of its Kleenex tissues, Huggies diapers, and other consumer products. Like many other suppliers of goods and services, it took a hard look at the way it was tracking its products and deliveries before the installation, because determining the appropriate use of RFID is not always straightforward. Not only will the technology perform poorly or simply not work in certain applications, but many companies have already made huge investments in two-dimensional (2-D) bar code technology and are reluctant to spend the money to replace it.

当前RFID是由于大的兴趣激增ly to recent technological breakthroughs that have altered its economics and capability. Manufacturers have found a way to make propagative coupling, a technique used in radar, economical enough for use in RFID. Using 915-MHz ultrahigh-frequency (UHF) radio waves, this technique allows scanners to read from tags that are as far as 15 feet away. This distance makes it much easier to read several tags at once, which streamlines the process enormously.

“The common technology in the past used near-field technology, which required the tag and reader to be close enough to induce power using inductive coupling,” notes Michael LeGrega, a consulting product engineer for RFID and vision systems at Siemens Energy & Automation, a vendor of RFID technology based in Spring House, Pa. This distance was typically about a foot.

Because of the new economics and the mandate from Wal-Mart Stores Inc., Bentonville, Ark., RFID makes sense for Kimberly-Clark, and management there has invested heavily in it. Earlier this summer, the company installed the first standard interfaces between Auto-ID Infrastructure (AII) from software giant SAP AG, of Walldorf, Germany, and the OAT Foundation Suite, RFID software from OATSystems Inc., of Waltham, Mass. Information flows between the RFID tags and the mySAP ERP system through the AII software, which SAP designed to plug into its ERP package.

Best RFID practices

To reap the greatest return on its investment, Kimberly-Clark began the project by standardizing on the best practices for building and commissioning pallets to increase efficiency. Its systems engineers then worked with OAT to install RFID and deploy electronic product codes (EPCs) in a way that would supply useful information, automate edge processes, and provide the flexibility necessary for adapting to changes in the future. The AII software issues the EPCs by stock-keeping unit and customer order, creates unique serial numbers for each pallet, puts the EPC data into the appropriate business context, and automates business transactions within the ERP system based on movements of the RFID tagged cases and pallets.

So while Kimberly-Clark fulfills an order from Wal-Mart for diapers, for example, an RFID scanner reads the codes in the tags on each case of diapers and sends them to the computer system as workers stack the cases on pallets containing the rest of the retailer’s order. The software verifies that the cases going on the pallet are indeed part of the order and uses the codes to create a kind of digital picture of the object to keep track of contents of the pallet.

Rather than simply knowing that Wal-Mart received ten cases of Huggies, both Kimberly-Clark and Wal-Mart know which pallet contains a particular case of the product. This knowledge has huge ramifications. Whenever a case of product moves, each company not only knows where, but also can automate many of the associated business tasks, such as comparing deliveries to orders, issuing bills of lading, and conducting the appropriate credit checks. Traceability could cut the number of charge backs (corrections to bills) by as much as half, notes Eric Domski, SAP’s RFID solution director, based on his experience with other companies dealing with Wal-Mart.

Pursuing pesky pallets

Domski also reports that the traceability offered by RFID is proving to be a crucial component of the competitive strategy at CHEP International Inc., a company based in Orlando, Fla., that leases pallets and containers to manufacturers and retailers worldwide.

To track the more than 250 million assets that it has in the field, CHEP has completed several pilot programs for placing 256-bit tags on the center block of its pallets. Half of the tags’ data storage will contain a kind of serial number called a global returnable asset identifier (GRAI), which CHEP will use to track its pallets. RFID scanners will read the GRAIs and transmit them in batches to the SAP software as electronic data interchange (EDI) messages.

Another reason for choosing RFID is to exploit its rewriteable memory. CHEP is reserving the first half of the 256-bit storage space on the tags for its customers to place the serial shipping-container codes (SSCCs), which is a kind of license plate for pallets that describes their contents. “They’re leveraging the flexibility and capability that RFID offers that 2-D bar code would not, meaning the read-write capability,” says Domski.

These advantages notwithstanding, RFID based on propagative coupling has some important limitations that convince many factories to install bar codes instead. The metals, fluids and electromagnetic interference common in discrete-parts manufacturing and other industries make radio communications in the UHF range either erratic or impossible. “High frequencies, just by physics, are absorbed by water or liquid and are reflected by metal,” explains LeGrega, at Siemens.

Another limitation of RFID is that attaching to products is not usually desirable for traceability in the field. Many manufacturers in the aerospace, automotive and other industries put permanent identifiers on their products to serve as traveling databases that remain with the product throughout their lives. Their purpose is to retain the ability to trace the cause of any defects that might surface later and to streamline and narrow the scope of any recalls. “For automotive and aerospace, you can’t put a perishable label on an engine component,” says Jeff Schmitz, manager for vision sensors at Minneapolis-based Banner Engineering Corp. “You have to mark it directly, and I’m not aware of any technology other than 2-D bar code that fills that need.”

Cost and reliability are other reasons that many manufacturers prefer bar codes. RFID tags can cost 20 to 25 cents or more per tag, whereas bar code labels can cost less than 0.01 cent per label. Then, as is the case for all emerging technologies, results are often unpredictable.

“Industrial applications for RFID are not ruled by the same cost pressures as the commercial applications one reads about,” counters Helge Hornis, intelligent systems manager at Pepperl+Fuchs Inc. of Twinsburg, Ohio. “Systems are typically small and ‘closed loop.’ The tags do not leave the installation, so the cost per tag is not such a critical issue. This does not mean that integrators and machine builders are not watching cost.” Rather, the total cost of ownership tends to carry more weight.

Even so, manufacturers of RFID technology are taking action to minimize cost and reliability problems. Pepperl+Fuchs, for example, has designed a “continuous shield” into its Ident Control to give its products a measure of noise imunity.

When bar codes win

Nevertheless, manufacturing engineers at Delphi Energy & Chassis Systems specified 2-D bar codes when they decided to have “smart” parts, rather than smart pallets, flowing through a plant making antilock-brake components in Juarez, Mexico. Making the decision was not easy, though, because conventional bar code labels were not an ideal method either. The label had to be compact, permanent and capable of surviving the rigors of both production in the factory and final use in cars.

“We looked at various means of labeling our parts, such as RF tags, paper labels and ink jets,” says Dean Adams, senior manufacturing engineer. “But we quickly realized that the costs to implement were too high and the reliability was questionable.”

所以他和他的同事们决定在条形编码worked with Dayton Ohio, companies Bar Codes Unlimited Inc. and Omega Automation Inc. to specify the right technology.

The engineering team decided to stamp 2-D barcode directly onto the products with a pin-stamper from Telesis Technologies Inc., of Circleville, Ohio, and read them using Microscan’s Quadrus EZ bar code scanner. The Data Matrix code contains both the part number and date information so that smart cameras in the scanners downstream can verify that later operations are using the correct assemblies.

The next application of the technology was more sophisticated: The bar codes help the plant’s central computer system to trace the modulators’ progress through each station in an assembly cell. The first station in the assembly process identifies the machined casting, prints a serialized 2-D bar code that includes part number and date information, and sends this information to a database in the central computer. Each successive station then reads the code and queries the computer to determine whether the part has successfully completed the previous station.

Codes in Color

条形码和RFID availa并不是唯一的选择ble to manufacturers these days. ImageID Ltd., of Tel Aviv, Israel, is offering an unconventional color-code system called Visidot, a kind of code that stores information in dots containing patterns of various hues of color. “The readers take a high-resolution digital photograph of the asset, and our software finds the codes,” says Roger Hecker, product manager. The image-processing software then decodes the pattern of colors in each dot and exports in eXtensible Markup Language (XML) or other standard format.

Despite the success of RFID at CHEP International, IFCO Systems GmbH, of Pullach, Germany, another supplier of reusable plastic containers, found color codes to be more advantageous. Rather than continuing to use summary accounting, IFCO wanted to track with greater accuracy the more than 260 million rentals that flow every year through its network of 40 service centers and storage depots in Europe and North America. It wanted a system that would give its accountants accurate inventory counts at its depots in real time, keep better records of shipments, returns and cycle times, and improve its response times.

The Visidot scanners solve the problems by capturing an image of an entire stack of containers as the assets pass in front of them. In IFCO’s case, the scanners contain high-resolution cameras that can capture the color codes accurately from angles of up to 60 degrees and from several feet away.

Moreover, the readings are accurate. An audit shows that the system’s accuracy is 99.74 percent over 1.5 million readings, according to Stefan Mueller, IFCO’s vice president of operational planning and technology. The accuracy rating includes mistakes caused by dirty and missing tags and damaged crates. Given these results, perhaps color codes will be joining the fight between RFID and 2-D bar codes and expand the traceability wars.

For more information, search keywords “RFID” and “bar codes” atwww.myenum.com.