Is RFID ready for the plant floor?

The latest in wireless identification technology offers potential for using radio frequency identification (RFID) on the plant floor for asset maintenance. Most people use RFID technology on a daily basis without even realizing it. Have you ever used an electronic device in your car to automatically pay tolls? Do you use an access card or fob to gain employee entrance to your workplace? These e...

12/10/2004


The latest in wireless identification technology offers potential for using radio frequency identification (RFID) on the plant floor for asset maintenance.

Most people use RFID technology on a daily basis without even realizing it. Have you ever used an electronic device in your car to automatically pay tolls? Do you use an access card or fob to gain employee entrance to your workplace? These examples are common uses of RFID technology.

How RFID works

RFID tags work by emitting electronic signals — either actively with its transmitter, or passively by waiting for a signal from an RFID reader before reflecting back a response signal (Fig. 1). For the purpose of this discussion, the focus is on passive tags, which are significantly more affordable and more likely to be used in a plant environment.

Passive RFID tags can be read-only or read/write tags, allowing information to be updated with RFID readers that can be attached to standard mobile devices. Currently, the storage space on passive, read/write tags is approximately 2 kB, enabling only small amounts of information to be stored. But look for this number to grow as the technology advances.

RFID tags are available in a wide range of signal frequencies. Low-frequency tags typically operate between 30 and 300 kHz. On the other end of the spectrum, ultra-high frequency (UHF) tags operate anywhere from 300 MHz to 3 GHz, sending information faster and farther than lower frequency tags. Because they use more power, the higher frequency tags cost more, and are subject to limitations in transmitting signals when attached to objects containing water or metal. The distance most passive tags can be read from varies according to the frequency, ranging anywhere from a foot or less for low-frequency tags to 3 ft for high-frequency tags and 10%%MDASSML%%20 ft for UHF tags.

The higher frequency signals operate over longer distances. However, the higher frequency signals cannot penetrate through different substances as easily and therefore require line of sight (or at least a better line of sight). Therefore, the higher frequency readers have more problems reading tags where obstructions exist.

RFID facts and myths

RFID technology continues to evolve at a rapid pace. Spurred by the recent push from Wal-Mart and the Department of Defense (DoD) requiring manufacturers to standardize, a new market for RFID integrators has emerged and is stimulating its advancement and acceptance into the mainstream. As the technology grows and the costs of RFID implementations begin to decrease, greater opportunities for this emerging technology are being considered.

New trends in technology can sometimes be compared to an urban myth — it makes a great story, but in reality, is full of a lot of hype, mixed with little truth. RFID is often spoken of in the context of product tracking from production to distribution — the ability to identify a product, where it has come from and where it's going in the supply chain, as well as multiple traits about that product.

In reality, RFID tags for most products — as defined by standards being supported by Wal-Mart — would hold a 96-bit electronic product code, which is essentially a unique numeric code identifying the item, manufacturer, class of product, and serial number. But RFID has the potential to be much more than an electronic identification system for products moving throughout the supply chain — especially on the plant floor.

How the use of RFID and bar codes differ

The variety of tags and communications frequencies used by RFID is one of the technology's key advantages, offering plants the ability to vary the type of tag depending on the application. An additional benefit of RFID that other automatic ID technologies, such as bar codes, lack is the ability to read a tag without requiring line of sight (depending on the RFID frequency range). This feature is of particular use in industrial or dirty plant floor environments where dust, grease, or severe conditions could render bar codes unreadable.

RFID will not necessarily replace bar codes, but will likely be used in tandem depending on the environment. RFID tags can be protected from various elements by enclosing them in plastic casings, because only the signal needs to be received, rather than the visual requirement of bar codes. RFID tags can be welded or mounted onto an object, often at a distance from the ground. In addition, combining RFID tags with sensors introduces the possibility of capturing and transmitting temperature, vibration, or other important equipment readings. This combination is the beginning of a new practice that will offer tremendous benefits to plant floor data collection for years to come.

RFID on the plant floor

Industrial plants can benefit from these recent advancements in RFID, especially in maintenance and engineering functions. RFID is moving beyond merely an automatic identification technology to play a key role in holding information of value to workers at the point of performance. Information that can be stored on RFID tags includes:

  • Manufacturing specifications

  • Preventive maintenance schedules

  • Previous work orders (quantity varies according to tag memory)

  • Last several readings (quantity varies according to tag memory)

  • Measurement limits

  • Critical spare parts lists.