Sticking a normal RFID tag on metal is so much trouble. It does not seem to connect, right? The radio waves bounce right off! Metal messes with radio waves, rendering standard RFID tags useless. But don’t worry; tagging metal is possible, it’s just a matter of technique. This guide will cover all you need to know about RFID tags for metal surfaces.
What Is an On-Metal RFID Tag?
The term on-metal RFID tag refers to an RFID tag mounted directly on metal, with the antenna and the underlayer able to function on metal.
Near-metal tags are located near metal without contacting it, while in-metal tags are situated within a cutout, with the RF side of the tag exposed.
An anti-metal RFID tag is designed to work on metal, but that doesn’t mean it can handle every harsh condition. Ruggedness is a separate factor. Check the specific model’s ratings for water, impact, temperature, and chemical resistance before choosing it.
Can RFID Tags Work on Metal Surfaces?
Yes. RFID tags operate on metal when the antenna and its base are designed specifically for metal surfaces. On-metal RFID tags also named as metal RFID tags, metal-mount RFID tags, or anti-metal RFID tags.
Why Standard RFID Tags Fail on Metal
A regular UHF tag is designed to function with paper, plastic base, or open air. In contact with a metal surface, the antenna tuning is affected, the chip gets less usable energy, and the read range decreases.
Metal also reflects UHF waves and creates weak read zones. HF and NFC face other problems with metal, as it distorts magnetic fields around the antenna, which prevents a regular NFC tag from functioning on steel.
Why On-Metal RFID Tags Continue to Work
On-metal RFID tags are designed to manage antenna tuning with a special foam layer, ferrite layer, printed circuit board, ceramic, or the metal surface itself.
Impact of Metal on RFID Tags
Rfid Tags mounted on metal surfaces like plates or containers still function if there is no disturbance in the tag and antenna’s coupled field. The following points address the impacts of metal surfaces on RFID tags.
- Signal Reflection:Metal surfaces, with their capacity to reflect radio frequencies, can reflect radio signals. Reflection of the signal can introduce signal cancellation or multipath phenomena. This may lead to getting tagged for incorrect information or not reading it.
- Signal Absorption:The more important issue related to reflection is absorption. Reflection of signal may be helpful, but absorption of multiple signals to narrow the reading range is not. Some metals, unfortunately, do that.
- Detuning: Metal may want to interfere or cause some interference with the antenna of an RFID tag in the form of detuning. If it does that, the resonance frequency of the tag will be changed, so its functionality shall be affected.
How RFID Tags Work on Metal Surfaces?
RFID tags made for metal surfaces are specially designed to function accordingly to fuse the metal plate without compromising the signals.
- Shielding: These types of tags use monitoring antennas, which shield the tag’s antenna with metallic layers merged together specially to enhance the tag’s performance on metal surfaces. Increase guidance and as a result, reduction in interference helps in gaining better reception.
- Specialized Antenna Design:In contrast, metal-mountable RFID tags use specially designed antennas that develop good coupling when placed near magnetic metal surfaces. These could be different materials and shapes or different orientations.
- Encapsulation:The tag’s components are encapsulated by protecting them with strong materials to cover them from damage and to create a protective barrier between them and the metal surface.
Foam or Dielectric Spacer
A foam or dielectric spacer is positioned between the UHF antenna and the metal. This layer minimizes detuning and ensures that the label remains readable after installation. It’s ideal for printable asset labels for flat metal surfaces. However, the added thickness makes it unsuitable for small curvatures, high temperatures, oil exposure, and shock.
Ferrite-Backed RFID Tags
HF and NFC tags are coated with ferrite to direct the magnetic field away from the metal surface and ensure reliable short-range reading.
These tags are a good fit for phone taps and quick checks on pumps, machinery, and maintenance points. Note that HF and NFC are designed for short-range reading, so they won’t provide the same distance as passive UHF. The ferrite layer also makes the tag slightly thicker.
PCB Antenna Design
PCB tags are rigid tags with an antenna designed for metal surfaces. They are suitable for adhesive or screw mounting. They are convenient for flat and slightly curved industrial assets. But, tight pipes and cylindrical objects cannot accommodate them because of the rigid body of the tag.
Ceramic RFID Tag Design
Ceramic RFID tags are small, and many models can handle more heat than foam or plastic tags. They fit well on metal assets where mounting space is limited.
The downside is that ceramic can crack if it’s hit hard. A smaller antenna can also give a shorter read range than a larger on-metal tag. Ceramic tags are a good choice when you need a small tag that can handle heat, but they’re less suitable for equipment exposed to heavy impact.
Metal Ground Plane Antennas
Some UHF on-metal tags use the metal surface as a controlled ground plane for the antenna. When the tag is tuned for the right metal size and mounting position, it can provide strong read performance on machinery, containers, and other large metal assets.
The read range can change if you place the tag on a much smaller metal part or move it off metal. So, the antenna is no longer working with the metal surface it was tuned for.
Flag-Style RFID Labels
They are mounted on one side and have the antenna lifted from the metal plane. This way, it doesn’t touch the metal and provides space for printing identification. They’re appropriate for servers, electronics, and metal enclosures. The lifting makes them prone to wear through scraping and contact.
UHF vs HF vs NFC RFID Tags for Metal
| RFID Type | Metal Use | Typical Read Range |
| UHF | Asset Tracking and Inventory | Several meters |
| HF | Tool and Part Checks | Short range |
| NFC
| Phone-based service records | Tap range |
| Active RFID | Asset Location in Large Sites | Long range |
When to Choose UHF On-Metal Tags
Select UHF RFID tags for metal when you need extended read range, fast inventory, or multiple tags per reading. The tool room can take inventory of tagged tools using a handheld device without having to manually read each tool.
When to Choose HF On-Metal Tags
HF is suited to requiring a limited read range. At the workstation, the reader will verify one fixture without reading any other tagged assets that are beyond the short read range.
When to Choose NFC Tags for Metal
NFC technology suits tasks requiring phone taps. A maintenance worker can touch his phone to a tag on a valve, a pump, or a machine and then access its service record. Metal assets require NFC tags designed to work with metal.
When Active RFID Is a Better Choice
Active RFID is better for applications requiring long distances in yards, mines, or plants. It involves battery power, increasing the cost of the tags. If your application doesn’t involve location tracking, consider UHF RFID tags for metal.
Types of RFID Tags That Are Suitable for Metal Surfaces
Different forms of metal-mount RFID tags exist with differing mounting styles and form factors.
- Hard Plastic Metal Mount Tags:Having high IP ratings, these tags are tough and built to withstand severe conditions of moisture, dust, and heavy treatment. Ideal for harsh environments, they can be adhered to metal objects in various ways.
- RFID Metal Mount Labels:These labels have an added foam layer that absorbs radio frequencies. Unlike regular labels, they work better on metal. As a result, they are better suited for variable data applications because they can be printed and encoded by RFID printers on the premises.
- RFID Flagtags: These tags can be mounted where they will have the form of a flag and have one side coated with adhesive. These tags are more friendly to antennas and do not place them on metal. They add another level of intrusiveness while remaining reliable as tags printed on labels, inlays, and other durable plastic forms.
Printable Flexible On-Metal Labels
Thin tags go onto flat metal objects with little mounting surface. A barcode, QR code, serial number, or company logo can be printed on the tag face.
PCB On-Metal RFID Tags
The PCB design is a rigid construction that provides antenna protection and maintains its shape while mounted. Adhesive, integral screw holes, or both can be used.
Ceramic RFID Tags
Ceramic tags are suitable for use on small metal objects or in hot environments. Don’t mistake the maximum peak operating temperature for continuous exposure to that temperature.
Rugged ABS and Encapsulated Tags
Heavy equipment and outdoor assets deal with rough conditions, so a thin RFID label may not hold up for long. Rugged ABS and encapsulated tags offer better protection in these environments. The level of protection still varies by model. Water, dust, impact, extreme temperatures, and chemicals can all affect tag life and performance.
Screw, Rivet, and Bolt-Mount Tags
These tags go onto tanks, machinery, pipes, and other equipment subject to vibrations and impacts. Mechanical fixing is stronger than adhesive fixing when the tag is constantly moving. Use only the mounting holes designed for the tag.
Cable-Tie and Hang Tags
Pipes, valves, and cylinders don’t have flat surfaces suitable for adhesive mounting. Cable-tie and hang tags provide mounting around the asset. The tag angle and distance from the metal affect the read, so make sure the tag is tested in the desired mounting position.
Embeddable/In-Metal RFID Tags
These tags are installed in a slot, hole, or recess in the metal object. Leave the RF face free of metal. Metal on all sides prevents communication with an external reader.
Key Features and Specifications of RFID Tags for Metal Surfaces
- On-Metal (and Off-Metal!) Performance:These RFID tags are developed to function accurately on metal surfaces, where standard RFID tags normally struggle. Many are also engineered to perform well on other materials, providing flexibility for different tagging requirements.
- Read Range:A key feature is their extended tracking range which allows efficient monitoring of assets that are some distance away.
- Durability: Designed to endure tough conditions, these tags are moisture, extreme temperature, impact, and often chemical resistant. Look for specific IP ratings (Ingress Protection) to understand the level of protection against dust and water.
- Form Factor and Mounting:Each tag is designed in different shapes and sizes and has a variety of mounting methods to best suit how you need to affix the tag and your particular application.
- Compliance:Tags designed by reputable manufacturers are made with the required industry regulations and quality control standards.
- Detailed Specifications:Every tag model comes with specific read range, memory capacity, and materials, among other details. Be sure to review these specifications for each tag model to ensure you select the right tag.
Key Considerations When Choosing RFID Tags for Metal Surfaces
When choosing an RFID tag to be used with metal, careful consideration is required. The outlines that follow can assist you in making an educated choice:
- Type of Metal: Different metals impact the RFID signals in differing ways. Steel, for example, reflects more compared to aluminum so it might require more shielding.
- Environmental Factors: These cover temperature, humidity, and any chemicals. If the tags are meant to be used outside in regions where moisture is high, then it is essential to ensure that the tags are more IP rated so that they are effectively protected.
- Reading Distance:Estimate the distance from which the tag will be read. If a few feet is the answer, then a long-range tag will be required.
- Tagging Method: How will the tag be attached? To ensure that tags are securely fastened to metallic devices, it would make sense to attach rivets or screws to them. To guarantee that the tags stay in their correct places on little things, the adhesive should be especially strong.
- Data Required:How much data needs to be stored? If the only data you require is a unique ID number, memory tags with low capacities are best suited. Maintenance history and other pertinent details can certainly be stored on higher RPM tags for easier retrieval.
- Budget: Keep in mind that there’s an assortment of prices for RFID tags. While tags are being selected, quality should not be discounted for price.
How Far Can RFID Tags Read on Metal?
The reading range depends on the tag and the metal asset. A smaller tag for tools reads at a shorter range, while a large UHF tag may read up to several meters away. Reading range depends on the tag size, reading power, antenna gain, metal area, metal shape, tag orientation, any liquid nearby, and reflections.
Perform testing of the shortlisted tags on the actual asset using the reading equipment. Remember that the write range is different from the read range.
RFID Metal Tag Applications
RFID Metal tags are utilized in a multitude of markets including the following ones:
Manufacturing Tools, Molds and Fixtures
Tools, molds, and fixtures change location often and require tough labeling. Suitable types of tags for them are PCB, ceramic, and hard UHF tags.
Automotive and Aerospace Parts
A combination of metal, oil, fuel, vibrations, and heat is typical for engines, gearboxes, jigs, and repair equipment. On-metal PCB, ceramic, or hard tags better accommodate those situations compared to common RFID labels.
Servers and IT Assets
For servers, switches, racks, and laptop tagging, there’s little space. Thin on-metal labels are suitable for inventory stocktaking using a handheld scanner without needing to scan every single barcode.
Gas Cylinders, Tanks and Pipelines
Curved surfaces demand an appropriate label type. Hard, bolt, cable-tie, or curved UHF metal-mount tags will perform better than flat adhesive labels in those positions.
Metal Containers and Returnable Transport Items
Cages, drums, kegs, and metal RFID pallet tags pass through inventory and transport processes. Using UHF on-metal tags allows items to be identified and counted without manual inventory.
Healthcare and Surgical Instruments
Small metal medical tools require tough labeling, as they can be exposed to repeated cleaning. Ceramic and embedded tags are best suited for this environment. Choose a tag according to the temperature or chemical resistance required for your sterilizing process.
Construction, Railway and Mining Equipment
Heavy machinery, rails, transport equipment, and tools are subject to dust, water, vibrations, and impacts. On-metal hard tags with screw, rivet, or bolt mounting are more appropriate under these conditions.
How Can You Attach an RFID Tag to a Metal Object?
- Adhesive:Use strong adhesive bonds for surfaces that are clean and smooth. You have to clean the tag by using alcohol wipes, secondly, apply glue to the tag and press.
- Screws and Rivets:For screws or rivets, the fastening is more rigid, especially in difficult situations. You first drill holes, then position the tag, and lastly, secure it with rivets or screws
- Welding:For demanding applications, welding the tag to the metal surface. This process will require specialized tools and knowledge.
- Cable Ties:Used along with tags for fastening to pipes or cables. Strap the cable tie to the part and to the tag.
Optimizing RFID Performance on Metal Surfaces
- Tag Location:The best tip for each test is locating the tags. Try many different spots to find which one works best for reading.
- Choosing a Reader Antenna:When selecting the most appropriate reader antenna tags and the application are the main considerations.
- Correct Installation: Tags have been fastened to the device and the tag has been placed on it so that the antenna points vertically.
- Regular Testing: It is best to the system frequently to determine if or how well the system was set up.
Frequently Asked Questions
Can RFID tags work directly on metal?
Yes. Use an RFID tag for direct metal mounting. The design of its antenna and backing ensures functionality after metal contact.
Why do normal RFID labels not work on metal?
Metal interferes with antenna tuning and RF wave reflection. It either decreases the reading distance or makes the tag unreadable.
What is the difference between on-metal and anti-metal RFID tags?
Both terms refer to the same RFID tag type in most catalogs from different suppliers. They mean RFID labels for application on metal surfaces.
How far can RFID tags read on metal?
The reading distance of on-metal passive UHF tags changes from close range up to several meters, depending on the tag, asset, reader, and mounting.
Can NFC tags be used on metal?
Yes. Use an NFC label for application on metal, including a special ferrite layer under the antenna. A regular NFC label degrades when placed on metal.
Can smartphones read UHF RFID tags?
Smartphones usually support NFC tags, but not passive UHF tags. UHF tags require a separate UHF reader or a phone-compatible UHF reader.
Can on-metal RFID tags work on plastic?
There are all-surface tags that work on metal and non-metal surfaces. Metal-only tags might decrease in efficiency on plastic, so test the tag on both surfaces.
Can RFID signals pass through a metal enclosure?
A fully closed metal box doesn’t allow communication with the tag from outside. Ensure that the face of the tag remains accessible.
Which RFID tag is best for curved metal surfaces?
Flexible on-metal tags, cable-tie tags, or hard tags designed for pipe or cylinder applications are ideal choices for curved assets. Choose a tag according to the curvature and diameter of the asset.
Are on-metal RFID tags waterproof?
Choose a suitable model according to your IP rating requirement and review the test conditions for that model. Waterproof properties depend on tag design.
Which RFID tags can withstand high temperatures?
Ceramic or heat-resistant hard tags accommodate most high-temperature applications. Review the temperature ratings before application.
How should RFID tags be attached to metal assets?
Adhesive, epoxy, screws, rivets, rfid cable ties tag, or curved mounts, among others, can be used depending on the tag body, asset, and operating environment.
Conclusion
RFID tags for metals offer the best value if you are looking to optimize and control over your metal assets. Considering how metal surfaces respond to RFID signals, selecting the suitable tag type and system specifications, as well as system tuning allows you to enjoy very significant benefits.
