|Handheld devices have made RFID reading a fast and easy operation.|
|Active vs. Passive Tags
RFID tags are classified as being either active or passive. Active tags have small amounts of memory that can be utilized to store information that is transmitted to them, whereas passive tags are limited to a single identification number that cannot be changed.
Passive tags are made up of a microchip and an antenna. The identification number on the passive tag is either pre-programmed at the factory or can be programmed by the user. Either way, once the identification number has been initiated, it cannot be changed.
In addition to the antenna and microchip, the active tag also contains a built-in battery. The battery supplies the energy necessary to maintain the writable memory on the microchip. In addition, the battery boosts the strength of the transmitting radio wave, making the reading distance of the active tag much farther than that of the passive tag.
Even though there are advantages in using the active tag over the passive tag, the passive tag is far more prevalent due to the relative cost. Passive tags can cost between 10 cents and $1, whereas active tags can cost more than $20.
â Tim Stiess and Earl Kline
RFID tags can vary in shape and size. However, it is important to note that a small and compact tag means a small and compact antenna, which can result in smaller distance capabilities between the tag and the reader.
The most popular RFID tag is the inlay tag. It is very flat and contains a large antenna. This shape makes it possible to incorporate into a shipping label. For maximum application flexibility, the label on a product can then be labeled multiple ways: RFID, barcodes and alpha-numeric.
Special label printers can be purchased for inlay tags. Information typed into a form can be printed on the label, bar code and encoded in the RFID inlay tag â all in one step.
RFID readers are the complementary equipment for the tags. As its name implies, this is the device that âreadsâ the information transmitted from the tags. In many cases, the âreaderâ is a combination of the reading device, the energy transmission device for the tag and, in some cases, a computer.
Handheld readers typically perform all three applications. At the pull of a trigger, this reader sends out an energy signal and any tag within its range will be identified on the small computer display. The downside to using this type of equipment is the battery, which limits the energy signal strength for shorter read distances.
In addition to the handheld models, RFID readers can be attached to a conveyor, forklift, or a work table. They are typically tied into a network so that current information can be obtained directly at the appropriate workstations.
Another popular form of RFID reading device is the portal, sometimes called a gate. The portal is a doorway or frame with RFID readers all reading toward the opening.
The orientations of the RFID readers minimize or negate places where tags can hide as they pass through the portal. Portals are very handy to have on each truck in the shipping department or between inventory and production, as a means of tracking material movement and identifying current locations of items.
Costs of RFID
In a manufacturing operation, each RFID implementation is unique. Determining the cost of RFID requires a consultant, or working closely with an RFID service company, to estimate the network of computers and software needed to make RFID an effective system.
Aside from the computer needs, RFID equipment is not necessarily an expensive technology. With individual readersâ costs ranging from $500 to $3,000, an entire shipping department can be set up with readers and a limited network for under $20,000, thereby giving companies the ability to monitor tagged orders as they enter trucks.
And while the cost for individual tags is not necessarily expensive, the cost of tagging each item can be prohibitive. Passive tags can cost between 10 cents and $1, while active tags can cost more than $20. Some companies try to reduce costs by buying more expensive reusable tags, which increases the initial cost, but can lead to savings over time.
RFID is a powerful tool, but it is only that â a tool. As with any implementation, a detailed analysis and feasibility study needs to be performed prior to any decisions. The cost of implementing RFID incorrectly may be far greater than not implementing it at all.
Tim Stiess and Earl Kline are associate and co-director, respectively, of the Sloan Forest Industries Center at Virginia Tech. The Centerâs mission is to promote the global competitiveness and sustainable growth of Americaâs diverse forest industries. The RFID research was funded in part by the Wood Education Resource Center, Princeton, WV. For more information on this topic or the Sloan Forest Industries Center, contact Tim Stiess at (540) 231-3846, or at firstname.lastname@example.org.
|RFID in Action: Cabinet Manufacturing Plant
One of the major challenges in large-scale wood products manufacturing is keeping track of all the cabinet components as they make their way through assembly, sanding, staining and other processes. For example, if a facility produces more than a thousand doors a day, by the end of the week hundreds of components have been pulled off the line, and in some cases, lost from the original order grouping.
To alleviate the problem in this type of manufacturing process, RFID technology is being implemented as a work-in-progress, flow-tracking system to eliminate problematic production points where doors and panels are removed from assembly for repairs, or simply get off track. The technology can also be used for tracking finished goods.
Case in Point
Knowing that cabinets cannot have RFID labels sticking out in plain view when complete, the tag needed to be placed in a way that it did not affect the finished product to any noticeable degree. This challenge became even more difficult, because cabinet manufacturers have varying methods of production, making a tag hard to hide and nearly impossible to keep attached to the panel or door.
Three options for RFID tag placement yielded similar, effective results: a puck for hinge holes, a reusable label that attaches to the inside panel and an embedded tag which could be concealed from view.
Since many manufacturers already cut a hinge hole during the final stages of processing the cabinet doors, it was quickly realized that this would be an ideal, initial spot to attach a removable and reusable RFID tag. The tag was designed in a plastic encapsulation, to be placed in the hole with a friction fit.
While this approach satisfied a subset of manufacturers who utilize this style of hinge, the solution would not apply to those manufacturers who do not cut hinge holes into the door. Base cabinet wood panels also presented specific challenges as hinges are not required, thus leaving no ideal position for tags to be placed. Along with these factors, the tag needed to withstand the process of sanding, finishing and drying.
Thus, a second tag solution was to utilize a reusable RFID tag. As the components reach the final stages of processing, the RFID tags can be removed and then reattached to a new part at the start of the process. The cost justification for the more expensive, reusable tags can be made: the multitude of doors running through the manufacturing process on a daily basis can now be tracked at a ânon-intrusiveâ level.
If options 1 or 2 are not feasible, and there is a desire for an even greater read distance, a third option would be to implant RFID tags internal to the door fabrication. This option is currently being deployed in some plants.
Tracking Made Easier
With tags now placed on a very high percentage of the wood components, cabinet manufacturers can place RFID readers and antennas in key spots on the production line and throughout the supply chain.
As the wood products make their way through the production process, the tags are read by a RFID antenna, pushed through the RFID reader and the associated data is populated into a database. This data can be transferred into a new or existing shop floor management software system or compiled into custom reports for analysis by authorized management personnel.
Visibility of each order is now much higher, doors and panels stay together better and fewer mistakes are made. This drives costs down and improves production and delivery times by reducing the time spent matching parts during work in process.
- Matt Foreman
Matt Foreman is involved in sales and engineering for Northern Apex-RFID. For more information on this topic, e-mail email@example.com or visit www.northernapex-rfid.com.
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