I am looking to track small tools, and prevent them from being stolen, within a manufacturing environment. Which RFID technologies or applications are suitable?
The answer depends on the business processes involved, as well as your specific environment. In general, there are some challenges in tracking small tools with RFID, particularly if they are made of metal. Low-frequency (LF) tags can be small enough and can work well around metal, but the read range (a few centimeters) is too short to make it an effective tool for preventing theft. If someone were to walk out a door with a tool, an interrogator would probably not pick up its tag.
High-frequency (HF) tags offer a longer read range, but still just three feet or so. So you would not be able to track tools in a large facility unless they were to pass through doorways or portals. Ultrahigh-frequency (UHF) tags offer longer read range (up to 30 feet under ideal conditions), but you would need tags specially designed for metal tools.
All passive tags can be shielded from a reader by the human body, tin foil or Mylar, which means that employees can figure out how to steel an item without being detected by an RFID system. Active tags, however, are probably too large for your tools—it depends on what you mean by "small tools." What's more, active tags are more expensive than passive tags, so if you have a lot of small tools to track, the cost of active tags might be prohibitive.
Does that mean RFID is unsuitable for your purpose? Not necessarily. If the tools are checked in and out of a tool crib, then RFID can be an effective way of linking each tool to the person who checked it out.
Even if the tools are stored in a cabinet or cage, RFID could still be a good solution. For instance, you could tag each tool with an HF or UHF tag, and give each employee an identification badge with a tag in it. The employee would use the badge to open the cabinet or cage, and when the tool was removed, software would link the ID in the badge to the item taken out. If the item was not replaced, there would then be a record of who had checked it out.
If you don't use a tool crib, cage or cabinet, another option might be to utilize an RFID system combined with a video surveillance system. Let's say you have various stations within your facility at which tools are used; a UHF reader and antennas could be installed above each station. As an employee uses a tagged tool, a UHF system would track it, and software would embed the ID of each tagged item in a file with the digital video from the surveillance camera. Your company could quickly take inventory with a handheld RFID interrogator, and if an item were stolen, you could then search the video file for the embedded ID and quickly call up the proper video recording that would reveal the last employee to use that particular tool.
These are just some of the factors that can influence the technology choices for your application. I would be happy to discuss this in more detail over the phone. A good systems integrator could also walk you through different choices based on your processes, environment, budget and so forth.
—Mark Roberti, Editor, RFID Journal
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