fbpx
Back

January 1, 2011

A Slab by Any Other Name

Metal can negate RFID systems, but companies such as ThyssenKrupp and Timken have found ways to use the powerful identification system anyway.

''Steel slabs look very much the same,” observes Loic Feinbier, and for him this is much more than a casual, albeit correct, observation. Feinbier heads the ThyssenKrupp Steel AG team charged with developing a foolproof way to keep precise track of some 250,000 slabs produced annually by the company's new mill in Santa Cruz, Brazil.

Of course, the task isn't limited to the slabs stacked in disciplined rows in the mill. Feinbier, leader of the company's Leiter Center of Competence for Supply Chain Visibility, developed a way to identify quickly each individual slab during the long and complicated journeys to rolling mills in Calvert, Alabama, and Germany via sea ports in Mobile, Alabama and Rotterdam in the Netherlands. Along the way, each slab goes through a half-dozen loading cycles as it moves through a two-continent suite of shipping and storage options involving trucks, ships, barges, cranes and storage yards.

Here's the rub. Those slabs, weighing 25 tons on average, packed tightly in a ship's hold, grind against one another, potentially obliterating bar codes, painted identification numbers, etched-in information, stowaways and rats. Yet at the next port, ThyssenKrupp has three nonstop minutes or less to unload each slab, identify it conclusively and place it on the right truck for transport to its next correct stop. It costs, ThyssenKrupp figures, $1.50 per ton per day when a ship is in port, a small amount that nonetheless rapidly erodes the cost advantage the company gains by making steel practically adjacent to the world's best iron ore in Brazil.

“The problem is,” says Feinbier, “that when you load those slabs on a ship, they are in a chaotic warehouse. You don't know where a slab will be put, and so your slabs lose their identity. And of course, they all have different steel qualities, dimensions and so on. You must not mix up your slabs.”

Old Tech, New Use

To accomplish this, ThyssenKrupp has adopted a new version of a 40-year-old technology called radio-frequency identification, or RFID. RFID systems, common in retail warehouses, consist of three important parts. First, there's an antenna, which beams radio energy that powers the second component, the RFID tag, or chip. The tag responds to the energy by broadcasting its unique number. That number is entered automatically into a computer system, thus verifying that the tagged product—a shirt at Wal-Mart, say, or a steel slab emerging from a hold, a pallet of ammunition tracked by the Army, or a steel barrel filled with a particular chemical—has arrived, moved or otherwise journeyed from one place to another.

RFID systems have a number of virtues. They are fast, comprehensive and automatic. They can be relatively inexpensive. They can provide unique identifying numbers for better inventory and logistics control. Yet despite these advantages, they have not been broadly adopted by metals companies because tags attached to metal don't work. “If you put a tag on metal, the energy from the antenna is dissipated, so the chip won't power up,” says Jeffrey Tazelaar, RFID product manager for Lowry Computer Products of Brighton, Michigan, a specialist in mobile identification systems.

What's changed? The technology has matured, says Tazelaar, and new tags and labels have been developed that securely attach to metals yet maintain a quarter-inch or more of distance between the RFID chip and the metal surface. At that distance, the tags suddenly begin to work well.

So at The Timken Company's Gambrinus Steel Plant in Canton, Ohio, shipments of some 12,000 tons of bundled tubes each month include a hanging RFID tag that's automatically read at a portal. As the truck passes through the portal, the computer system reads the RFID tags and compares them with the tags and bundles that are assigned to the bill of lading. Discrepancies arise instantly and can be corrected without a misshipment.

Timken began investigating RFID in 2008 to help improve its shipping process. “An error doesn't seem too serious until someone forges a component out of the wrong grade of steel,” says David Haslar, unit manager, shipping services, for the company's Alloy Steel and Steel Components Division. “If that happens, then it's a major problem.” Now, Timken loads 250 trucks daily and has all but completely dispensed with manual reads of bundle bar codes. Haslar says the company plans to use RFID technology to track 70,000 tons of bar shipments monthly. “We haven't found any downsides to this technology,” says Haslar.

Dow Corning Corporation has experienced a 100% read rate on 55-gallon, liquid-filled steel drums since developing its RFID identification system several years ago, says Dave Zuwala, technology steward for data collection at the company. “Sometimes, bar codes don't work,” says Zuwala. “For example, if you want to take four drums from one area to another. With RFID you can do that. With bar codes, it is slower and more hands on. Or, say you want to know everything that's in a cooler, or when the drums were put in or taken out of the cooler. RFID fits that much better than bar coding because it reads the entire batch at once.”

Like Timken and Dow Corning, ThyssenKrupp had to experiment with RFID labels to determine which might work best with its slabs. The company developed its own labels working with S+P Samson GmbH, an RFID label producer based in Kissing, Germany. A significant problem was establishing what adhesive would work reliably on a slab, which can be very warm or very cold and covered with cinder, rust, dirt or moisture. The slabs also require labels strong enough to withstand the rigors of a ship's hold, with a corner that could pop away from the slab as soon as it is lifted away from the stack. “Most projects in this field die due to lack of stamina in testing and the will to go forward with a new technology,” says Karl Tochtermann, S+P's CEO. “Labels for this kind of application are not ready made.” ThyssenKrupp, for example, required two and a half years to develop its label.

ThyssenKrupp sticks two of its custom-made labels on every slab, which speeds slab identification and provides redundancy should one be crushed in transit. Workers quickly buff a relatively clean spot on the slab and attach the labels. Readers at Santa Cruz first identify each loaded trailer, then record each slab at the port for outgoing shipments, again during unloading in Alabama or Rotterdam, reloading onto barges or for warehousing, when unloaded at rolling mills and, finally, at the roller table at the hot strip mill.

Read rates, says Feinbier, range from 92% to 94%. When RFID fails, he says, bar codes or ID numbers are read manually. “We're way better than what we thought was realistic,” he says. “We're confident that with practice, we can move the read rate up by one or two points.”

So, is RFID a technology ready for metals industry prime time? Feinbier says yes. “It's of interest in many different domains,” he says. “It has not been classically used in the steel industry. But now it comes in many different flavors. We are now extending our work to the entire ThyssenKrupp group.”