Metals and Liquids: RFID Kryptonite?

A recent conversation with my seven-year-old nephew turned to the new Superman movie. “Superman is cool because he can bend steel with his bare hands,” he told me.

Ironically, his statement made me think of an e-mail from a reader who was searching not for someone to bend steel, but for an RFID product that could read tracking data through steel—a superhero technology, if you will.

The e-mail came from Marlon Philippi, director of logistics for Hoffman Enclosures Inc., an electronic enclosures manufacturer in Anoka, Minn.

“We produce approximately 10,000 different SKUs, 90 percent of which are made of steel,” Philippi writes. “We are interested in using RFID technology to improve productivity and reduce waste. But, by the time our order picker brings a full pallet to the dock for shipping, we can’t read the RFID numbers for validation because RFID does not transmit through steel.”

What kryptonite is to Superman, materials such as metals and liquids are to RFID. They diminish its tracking powers by interfering with the strength and range of the tag’s RF signal.

Because there is no Supply Chain Man who can bend steel into RFID-friendly matter, I turned instead to some RFID companies to help Philippi.

“RFID as a technology does not penetrate through metal; it’s physics,” explains Bill Arnold, chief strategist for Omron RFID, headquartered in Kyoto, Japan.

But in some cases, RFID can be used around and on metal with positive results, he says. Companies should prepare, however, to incur additional costs and sacrifice a certain degree of read-range efficiency when using the technology on RF-unfriendly materials.

Heavy Metal

“Steel is not a 100-percent barrier to radio frequency signals, but a big factor in signal strength and range,” explains Marc Mitchell, transportation practice director, Enterprise Information Solutions Inc., a Downers Grove, Ill.-based systems integration firm.

“Signal strength presents a problem for reading individual components on a high-speed assembly line, or boxes on a forklift zooming past a portal. But some available tags will read a small number of steel items using a handheld device in close proximity.”

One proven solution for metals applications is active RFID operating at 433.92MHz, says Mark Nelson, director of corporate communications for Savi Technology, an RFID solutions provider based in Sunnyvale, Calif.

“This frequency has proven the most effective in ‘heavy metal’ environments because of its accuracy and ability to ‘bend’ around metal,” he says.

Because of its long wavelength, the 433.92-MHz frequency is better suited to refract around obstructions such as metals and liquids.

In addition to frequency, the key, Nelson says, is using active rather than passive RFID. Signal strength is greater with active RFID tags, which lessens metal’s kryptonite-like effect on RF signals.

“Battery-powered active tags have 60 times more decibel power than passive tags. As a result, data transmitted from active RFID tags to readers overcome many of the reliability problems associated with passive tags,” explains Nelson.

Don’t give up on passive tags just yet, however. Tag providers are looking for innovations—including tag packaging and placement—to help RFID perform better in metal environments.

And with total demand for RFID tags estimated to reach 5.5 billion units by 2010, plus growing use in metals-heavy industries such as automotive and aerospace/defense, RFID manufacturers are not likely to walk away from solving the metals issue anytime soon.

Omron for example, is “optimizing and testing tag designs specifically made for achieving good performance with RF-unfriendly products,” says Arnold.

It is also working with specialty converting companies that provide customized mounting and adhesive options to enhance passive RFID performance.

The company has had some success already with its “Loop” inlay tag, which is ideal for pallets, cases containing metal or high-moisture products, and applications that need readability from multiple orientations. The tags, Arnold says, read successfully when they are mounted on steel and directly face the read point.

But perhaps more important than the solution to the metals question is the lesson that a “one-size-fits-all” mentality doesn’t work for RFID. Companies looking to gain supply chain benefits from the technology—as well as RFID providers looking to reap marketshare—need to be innovative in their approaches.

“These materials challenges won’t impede RFID’s overall growth,” says Nelson. “The marketplace is discovering that different RFID technologies are available for different applications, and that readability issues can be overcome with new options and innovations.”

After all, Superman had to innovate to fight kryptonite. And we won’t even get into his issues with lead.

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