When it comes to automation, if you had to guess where this or that technology got its start, you’d be safe to go with the automotive industry as your answer. So it’s not a surprise to find that RFID technologies really took off in automotive manufacturing and assembly—across multiple levels of tier suppliers as well as with the carmakers themselves.
RFID has always been tied pretty closely to automation itself, notes Mark Sippel, project engineering manager for Balluff. “The more automated something tends to be, the more likely you’re going to want to try to implement some sort of tracking or traceability,” he says.
And the more the value of automation works its way into other industries, the greater the need for automated track and trace as well. “With more automation, there’s less ability to manually be able to track or apply traceability for something that’s going through that process. Especially if you have robotics involved, a human won’t be allowed in there for safety,” Sippel says. Even smaller parts on a rotary table can be problematic for human tracking. “A part enters and leaves a rotary table that could be several feet in diameter, in an enclosure, and at a speed that a human being couldn’t track or trace in that environment. You might have an RFID tag implemented at that point, to allow each station to write information as it goes.”
Track and trace
Track and trace capabilities have certainly become vital for food and beverage and pharmaceutical operations, where 100 percent traceability is needed to document and report on their processes and to trace back to their origins in case of errors. RFID provides a way of automatically keeping track of containers, ingredients, sterilization/cleaning processes, etc., notes Nicole Lauther, head of business development for real-time locating systems at Siemens.
But track and trace have become increasingly important for other industries as well. “The demand for tracking products is important in every industry in order to stay competitive,” Lauther says. “Tagging objects makes them smart and we are able to collect data on the field level, which means industrial identification and localization technologies are enablers for the digitalization.”
This leads directly back to RFID for a growing number of work-in-progress (WIP) applications, particularly as cost comes down and the realization of the benefits grows. “This is especially true across multiple points within manufacturing, such as in automotive and pharma, where product and part tracking is critical,” says Don Eichman, RFID product manager for Turck.
“It certainly is a growing use case as more and more companies realize that they need transparency in their production processes, meaning they understand the benefits of tracking parts and knowing the status of objects,” Lauther says. Benefits include process flexibility, faster production steps, elimination of paper travelers, elimination of errors and missed operations, elimination of damage, just-in-time material delivery, automatic documentation and traceability, she adds. “All this helps companies to save time and costs.”
Engine manufacturers in the automotive industry can find multiple applications for RFID technology, Eichman says. “For example, when matching up parts like an engine block and a cam, time can be saved during the stacking process by already knowing which parts fit together,” he says.
RFID has been catching on in the appliance industry, where contract manufacturers in particular will often combine multiple products on a single line—whether simultaneously or one after another. The identification information moves with the product through the automated assembly process so that it can always be validating what work is being performed for that particular product, Sippel notes.
Aerospace has always had to comply with a higher degree of traceability in manufacturing. “In the past, most of that had been done manually through paper tracking,” Sippel says. “Now it’s moving towards the use of RFID, for example, to be able to provide that traceability—sometimes even if it’s still manual.”
Consumer goods have also been looking more to RFID, though mainly higher-end goods like electronics, primarily within the assembly and manufacturing process.
Machine tools can be fitted with RFID tags to track and download offset measurements (from presetter), setup parameters, usage and tool life data. Source: Balluff
The right tag for the application
There are several flavors of identification, and which one is best really depends on what a manufacturer is trying to achieve. On a broad level, there’s industrial identification like RFID as well as industrial localization, with growing use of real-time locating systems (RTLS). “One of the main differences is that with industrial identification you can say what it is and where it is when it passes a certain read point,” Lauther says. “With industrial localization, you can say what is exactly in which location in real time. You can use both for WIP; it just depends on how accurate you want to track it and what information you need to get in order to optimize your processes.”
Like much of the automation industry, earlier days of RFID saw technologies that were more proprietary—one company’s system didn’t work with another’s for multiple reasons. That’s still true to some extent, but the technology has moved more toward open standards.
Low-frequency (LF) tags tended to be very proprietary and weren’t really regulated by the Federal Communications Commission (FCC) because the band was so low, Sippel says. It’s still in existence today, typically used for livestock tagging, which is what drove the industry. Within the manufacturing space, LF is most commonly used for machine tools—mold and die tracking, and machine tools for traceability.
High-frequency (HF) RFID, running in the 13.56 MHz range, is considerably more prevalent in industrial manufacturing applications. Although an earlier protocol (ISO/IEC 14443) was generally more proprietary—and is still used mainly for security systems—the newer ISO/IEC 15693 protocol is an open standard. With 15693, any manufacturer operating on that protocol can access another organization’s memory and other information. This also means that a supplier that makes only tags or only readers can more readily compete in the market, Sippel notes. “That’s what really began to drive the market and more competition, in my opinion.”
More recently, ultra high-frequency (UHF) tags have begun to be used. Operating somewhere in the range of 860-928 MHz, this technology was originally driven by the consumer market—for example, by outlets like Walmart that wanted very low-cost tagging (less than a cent) to tag shipments all the way down to the individual item. “They were going to be able to put these things on shelves, track them on shelves, and you’d walk through portals at the cash register and it would ring you up,” Sippel explains. “But it didn’t work. There were too many issues involved with the physics, and it had very limited success.”
But UHF is finding a place in manufacturing. “Manufacturers who use HF-based RFID applications now have a much broader range of possibilities with the new capabilities that UHF RFID technology can provide as UHF has developed a lot over the years,” Lauther says. “However, UHF is not better than HF—just different with different capabilities and different deployment challenges.”
Compared with HF-based RFID technology, UHF provides longer read distances (up to 26 ft vs. within about 3 ft), can read more items at a time (about 1,000), and can read them at faster speeds. Where those longer read distances can come in handy on the factory floor is if there is something sticking out on the side of a cart that prevents a tag from getting closer to the reader—the UHF will allow for longer-range capability. “It’s giving us greater flexibility towards using RFID in those types of environments,” Sippel says.
It’s also been useful in heavy industries like the manufacture of trucks, tractors and buses. “These are much larger-scale manufacturing lines. UHF is really the technology to fit that well,” Sippel says.
This has been an area that Bluetooth beacons have operated in because they can work for longer ranges. But because UHF technology is passive, unlike the Bluetooth beacons, it doesn’t require a battery and tends to be more cost-effective, Sippel says. “You typically would not leave an active technology on a vehicle; it’s expensive,” he says. “But you could take a passive UHF tag, which might cost you a couple bucks at most, and you could leave it on the vehicle. That tends to be a little more attractive.”
UHF, however, offers lower memory capacity, Eichman notes, and manufacturers are more likely to need help from a system integrator. HF typically makes more sense if customers need higher memory capacity to store data on the tag, close-range reading, and a more rugged tag that is reusable, he adds. “For longer-range applications with lower memory requirements, then UHF may be more appropriate,” he says. “With this technology, the data is stored in the PLC or higher-level enterprise system rather than the tag itself.”
An RFID tag affixed to each container can enable the tracking of material loss for work in progress. RFID system integration with a PC or PLC host can be leveraged to provide notification to operators and management when material loss exceeds defined limits. Source: Siemens
RTLS comes into play when objects need to be located in real time. “It certainly provides an even higher transparency throughout the production process than RFID, but again it depends on what information you need for highest efficiency in the production process,” Lauther says.
Siemens recently acquired Agilion—giving the automation supplier key ultra-wideband (UWB) technology for RTLS. Siemens’ Simatic RTLS employs UWB technology, which uses an extremely wide frequency range (3-7 GHz) with a bandwidth of at least 500 MHz to transmit weak wireless signals. This prevents the risk of interference with other systems and provides precise object location with accuracy down to 10 cm.
RTLS technology is at the heart of Zebra Technologies’ MotionWorks, which provides insights into the location, condition and performance of critical assets, goods and people in a manufacturing operation. It uses a combination of 6.5 GHz UWB active RFID, 2.4 GHz active RFID, Bluetooth low energy (BLE) beacons and passive RFID to track assets and materials.
Known for its tracking of NFL players on a football field, Zebra finds it’s actually somewhat less demanding to track cars through a manufacturing process. In one scenario, a professional football player wears two RFID tags—one on each side of his shoulder pads—and another tag is in the ball.
“Seven times per second those tags emit a signal. It’s the highest-sensitivity tag that we use, and measures that person within 6 inches,” says Jim Hilton, senior director of manufacturing and field mobility for Zebra. “Imagine the data that suddenly became visible to coaches and trainers and such—how fast you’re running, your routes in the first quarter vs. the second, third or fourth quarter. And yes, there is a difference. Every bit of that suddenly became visible.”
It’s exactly the same technology used by Ford to track vehicles as they come off a production line. “But we don’t have to know that often or that precisely,” Hilton says.
One aerospace manufacturer uses MotionWorks to track the specialized tools used to complete the thousands of manual processes required to build an aircraft. Misplaced, misappropriated, unreturned or compromised tools can cause delays along the line and in delivery of the aircraft. Real-time tool and equipment visibility improved equipment utilization by 20 percent, reduced work delays caused by missing tools by 80 percent, and reduced out-of-certification tools by 30 percent. The manufacturer also reduced capital expenditure to replace “currently not found” items by 50 percent.
Active vs. passive
What technology you need and how much money you need to spend on it will vary by the business problem you’re trying to solve—what you’re trying to see, what you’re trying to accomplish, Hilton explains. “Generally, it’s somewhere within 20-30 ft of proximity,” he says. “That tag doesn’t have to emit a signal any more than once every hour or once every few hours. That turns the battery life of that active tag into years instead of having to be monitored more often.”
Active tags need to have batteries because they are sending out signals that can be picked up from 100 ft to a couple of miles away, depending on the strength of the tag and the problem being solved. With an active tag, a pallet could indicate where it is at all times. Or a bin sitting in a production area could send out a signal when it reaches a certain weight, indicating that it needs replenishing, Hilton explains.
Though passive tags don’t send out signals, they are useful for other applications, and have the benefit of not requiring their own power source. Instead, a reader picks up the tag when it gets in close proximity. A passive tag attached to a car on a production line, for example, could indicate not only what specific car it is, but also what five things the worker at that station needs to do on that particular vehicle. Passive tags, depending on their application, could be as cheap as 7-10 cents each, so they could get shipped out with a product and never come back.
Bluetooth, an active technology, is ideal for more advanced communication—with system monitoring applications, for example, Eichman says. It generally has additional sensors embedded into it, he adds, so it can be considerably more expensive.
BLE beacons could cost as much as $15 to $20 and last five years, Hilton says. They are generally fixed on something like an asset and used for proximity purposes. “If you’re walking through a plant with a mobile computer, and there are beacons on every rail, I can know where you are because that beacon senses your mobile computer being nearby,” Hilton explains. “That has all kinds of low-cost and low-disruption solutions because you don’t have to necessarily build the infrastructure—you just plant beacons around whatever you’re trying to track.”
“In a production environment, that kind of proximity to where you are in relation to a line can be important,” Hilton adds. “Maybe I don’t want the system to be able to start up unless everyone’s clear of that line. That’s a really cheap way of pulling that off.”
With Bluetooth, however, you can’t write and rewrite information to it like you can with both active and passive RFID. An RFID tag can store information about what an asset is, how long it’s been there, what kind of warranty it’s under, how many times it’s been worked on, and much more. “Every bit of that can be written on that tag, telling the worker about the asset they’re about to work on,” Hilton says. “Beacons just kind of raise their hand and say I’m here. Active or passive tags not only say I’m here, but here’s everything you ever wanted to know about them.”
Know your environment
Developers of RFID systems and applications now have more tools available to address a wider range of production requirements. “But, given those additional tools, they need to understand their target user scenarios especially well, including a scenario’s particular operating environment and the physical shape and material composition of the tagged items, cases or pallets being read and possibly written to,” Lauther notes.
Not all environments are suited to RFID technologies. “Something being exposed to an environment that’s highly caustic or high in temperature will preclude the RFID from being used,” Sippel notes. “The tags themselves can’t survive the environment.”
There are still ways to work with the information that RFID technologies can provide, however. Sippel points to an example with a tooling manufacturer that uses RFID only up to a given point. “When the tooling goes off to hardening or treating, it would destroy the tag. So then the information is carried up to a database and stored until the parts return,” he says. “When they come back from that environment, the information is reinstated back into the tag to carry on with that lot.”
Extreme temperatures can be a challenge, Eichman says, but not impossible to overcome. In fact, the technical advances made to enable RFID in harsher environments “is a never ceasing thing,” Sippel says.
“At one time, they weren’t capable of going above 85 °C. But today, they can handle 200 °C or 400 °F. The temperature has moved up pretty readily,” Sippel says. Caustic environments are not as damaging to RFID as they used to be either. “It used to be that a product looked like a small box in order to survive. And it had a pretty strict time limit. Now the exposure time can be considerable—it can operate a half hour or more and still have survivability. That’s the progression of electronics and tolerance and things of that nature.”
Much of the capabilities within harsh environments are achieved according to customer-specific needs. The housing, for example, will be tailored to what the RFID will be exposed to. “There are thousands and thousands of different caustics, so that has to be much more specialized,” Sippel says. “The biggest difficulty comes with things like penetrants. With deionized water, there are tags that can survive that, but it’s very narrow in terms of what materials can survive.”
Nearly every manufacturing environment can use RFID technology, Eichman says. “However, it becomes a balance of technology and process,” he adds. The adoption rate for all of these identification technologies is growing as users figure out how to use them more effectively. “As our knowledge grows, so do the products’ capabilities.”