Though still in the infancy stages in the woodworking industry, radio frequency identification already is helping companies improve tracking and production cycles.



By Tim Stiess and Earl Kline



What is RFID? Wal-Mart is using it. The Department of Defense is using it. Other woodworkers are beginning to use it. Should you?



Radio frequency identification is a way for computers to communicate directly with objects. If an object with an RFID tag comes within a certain radius of a reading device, a computer can identify the object, based on the information stored on the tag.



One of the most well-known uses of RFID is inventory management. RFID can be placed on parts or on locations within the inventory area to quickly direct a person to a specific part location and to verify that the correct one is in stock. If large objects, such as furniture or packages of lumber, are tagged, inventory could be performed by walking or driving by the tagged products with RFID scanners.



At the point of shipment, the RFID reader can record the exact moment a product was shipped, verify that the product was placed on the proper truck and identify any missing or partial orders. At the receiving end, RFID readers scan the orders as they are being picked up. On-board computers can then process the received orders and indicate where to take the orders.



RFID also can be utilized as an expeditor. If a product needs to make its way through a factory faster than others, an RFID tag can be attached to the product so that when it is in proximity to a work center, a reader can allow the worker to schedule production according to products with higher priorities. In addition, RFID can provide support for more automated manufacturing systems. An RFID tag can inform a conveyor as to an object’s size, weight, next process or previous process, and the conveyor will divert the object accordingly. An RFID reader can initiate a setup on a machine or provide the operator with the required information to complete the order.

Production analysis is another use for RFID. By putting RFID tags on products as they are being made, computer software can perform real-time analysis on the production process.



RFID Tags

The RFID tag is very simple. It is made up of a microchip that stores the required information and an antenna that broadcasts the information via radio waves.



Unlike a garage door opener, most RFID tags do not run on batteries. The RFID reading device, or sometimes a secondary unit, sends out a low energy field, which the tag captures and converts to an RFID transmission, which will be received by the reader.



The distance that a tag can be read by the reading device is a function of the relative strength of the signals. Signal strength depends on the strength of the energy field, the efficiency of the tags to change the energy wave into the RF wave, conditions that can block or interfere with the energy waves (i.e., metal, water) and the sensitivity of the antennas attached to the tag and the reading device.

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.



— 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 — all in one step.



RFID Readers

RFID readers are the complementary equipment for the tags. As its name implies, this is the device that “reads” the information transmitted from the tags. In many cases, the “reader” 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 readers’ 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 — 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 Center’s mission is to promote the global competitiveness and sustainable growth of America’s 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 tstiess@vt.edu.


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 “non-intrusive” 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 mforeman@northernapex-rfid.com or visit www.northernapex-rfid.com.


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