Do you know where your assets are? Radio-frequency identification (RFID) is the technology that identifies things, from the raw materials, spare parts and other items entering your facility, to the equipment that processes them, to the final product leaving your plant, and even the trucks and people that transport them. Large companies like Wal-Mart encourage their suppliers to identify their larger and more valuable products using RFID. So whether you think RFID is yet another technology that chips away at our privacy or envision RFID enabling significantly higher levels of productivity, there’s no denying it’s sweeping the industrial world.
RFID devices have been around since at least World War II, when they identified airplanes as friend or foe. RFID falls under the so-called automatic identification family of technology, along with bar code and smart card. Despite the long history of RFID, it’s only recently that its cost has been reduced enough to make it commercially viable relative to competing approaches. However, there’s still a long way to go before you’ll see RFID tags on inexpensive objects such as small electronic components and cheaper spare parts.
The typical RFID system has three components, namely, the tag, the reader and supporting hardware/software.
Tags are transponders
These also are referred to as transponders. A tag consists of a tiny antenna, a memory chip that stores information to be read and some sort of material that holds it all together. Some tags also might have a tiny power source such as a micro-battery.
The RFID tag is affixed to a given asset just like a bar code label. The difference, of course, is that the RFID tag is more versatile, albeit at a higher price point. For example, RFID tags can be equipped with a power supply, allowing users to read information off of the transponder with greater accuracy and from a greater distance because the signal is stronger.
Another advantage over bar code technology is that RFID uses radio waves so you don’t need to establish a direct line of sight with the reader. It also means you can read multiple tags simultaneously; in harsh, wet and corrosive environments if necessary; and through reflective materials if the tag is embedded within, say, a vehicle or container. The flip side to these advantages is that tags can be deliberately hidden somewhere on or within a given asset for easy tracking. This raises the ire of unions and advocacy groups who claim that management could be surreptitiously tracking the whereabouts of their maintenance technicians without them even knowing it.
There are essentially two tag types: active and passive. They vary in terms of how signals are received and transmitted, although there are many variations on these two themes.
A passive RFID tag can be read even though it has no internal power source. It is the simplest and cheapest of the two RFID types. A radio signal from a reader induces in the tag’s antenna just enough power to awaken the chip inside the tag and transmit back a weak response. Read-only passive tags are preprogrammed and the information stored in the memory chip can be read multiple times but can’t be changed. Other passive tags are read-write, meaning their memory can be changed or added to multiple times. Although these tags are more expensive, they offer greater flexibility. For example, they can be reprogrammed for another asset when the original one is retired.
An active tag can transmit a stronger signal because it has its own power supply. It can be read across a greater distance, such as identifying mobile equipment passing by a checkpoint several hundred yards away. These tags usually have a larger physical size to accommodate the battery and they only last as long as the battery functions, typically as long as 10 years. Active tags can be handy for continuously storing and transmitting to your CMMS an asset’s condition-based data, such as temperature or vibration. When purchasing RFID tags, consider the following factors:
Working environment: If you’re working in a harsh environment such as a meat-packing plant or near a high-temperature furnace, you’ll need to select a tag that functions reliably. The two most common environmental considerations are humidity and ambient temperature.
Location: Another key factor is the materials in the immediate vicinity of the tag. Many tags are weakened or rendered useless, for example, by simply wrapping them in aluminum foil. Location also dictates what form the tag takes. For example, you’d use a different shape of tag for embedding an RFID device on an employee badge than one buried in a component deep inside some production equipment.
Range: The shorter the range over which the tag can be read, the less expensive its cost. Most production equipment involves shorter distances because the readers and equipment typically are in fixed locations.
Size: Longer-range RFID tags typically are larger, especially if they are to be used under unforgiving conditions.
Frequency and regulatory compliance: There are numerous standards used in different parts of the world. For example, this includes the frequency ranges that are acceptable for a given country or region so that the tag will be compatible with other interfacing devices.
Readers may write
RFID readers, also known as interrogators, come in many shapes and sizes. Some are handheld devices for portability, such as for a technician conducting a PM inspection. Others might be in fixed locations, strategically placed by a door, for example, to recognize equipment, people and material passing in and out of the maintenance shop. The purpose of the RFID reader is simply to transmit radio waves to one or more tags, and receive the stored information back.
Supporting the CMMS
The CMMS is a good example of a system that can be integrated with the RFID reader to feed raw information from a transponder into the appropriate database and application. Sample CMMS-based applications that might make good use of RFID technology include:
- Condition-based monitoring, where the RFID device feeds readings on a continuous or batch basis for generating work orders or alarms.
- Time and attendance, where the RFID device tracks people coming and going from a given work area.
- Asset tracking, where mobile equipment or other assets on the move are tracked by fixed readers at known locations.
- Preventive maintenance, where technicians scan the equipment and spare parts used for facilitating data entry of work-order information.
- Inventory control, where parts are scanned at receipt, picking and placement into a given asset to facilitate data entry and the locating of parts.
As larger companies adopt RFID technology, the cost of tags and readers will continue to fall. However, there’s still a long way to go for low-volume, low-cost applications where the bar code still rules as the most cost-effective solution. Bar codes always will have a place in that they can do the job for less than a penny per bar code label. This would be difficult to beat, even after many more years, because an RFID tag is so much more complex than a simple paper and ink label.
(Editor’s note: The Plant Services CMMS/EAM Software Review, posted at www.PlantServices.com/cmms_review, provides a side-by-side comparison of more than a dozen popular software packages.)
E-mail Contributing Editor David Berger, P.Eng., partner, Western Management Consultants, at [email protected].