Flexible or Rigid? How to Choose On-Metal RFID Tags for Fixed Assets

Put an ordinary UHF label on a laptop lid and it reads fine. Put the same label on a server chassis, a steel cabinet or a machine tool and its read distance collapses — sometimes to a few centimetres, sometimes to nothing. It did not break; it detuned.

Metal beside an antenna changes the antenna: it pulls the resonant frequency away from the UHF band the tag was tuned for and reflects energy back into the chip. On-metal tags fix this by inserting a spacer or ground plane between the antenna and the metal, so the metal becomes part of the design instead of an obstacle.

After that, the choice is between two families — flexible and rigid.

Flexible On-Metal Tags: Thin, Conformal, Printable

SeeMore FL7030 flexible anti-metal RFID tags supplied on a roll

Our FL7030 is a 70×30×1.25 mm flexible on-metal tag: PET substrate, etched aluminium antenna, Impinj MR6-P chip, -18 dBm sensitivity. On metal it reaches 8 m with a handheld and 12 m with a fixed reader. It carries 128 bit EPC and 64 bit user memory, runs -20 °C to +75 °C, survives 100,000 rewrites and holds data over 10 years.

Being thin and bendable, it suits flat and gently curved surfaces — server front panels, laptop lids, monitor backs, metal shelving — and it prints and encodes on Zebra, Sato, POSTEK and Zmin printers, so EPC and a human-readable asset ID go on in one pass.

Rigid On-Metal Tags: A Shell That Takes Abuse

The SeeMore ABS 13042-95 rigid anti-metal tag, with through-holes for screw or rivet mounting

When an asset lives outdoors, gets washed down, or is handled by people who are not thinking about your tags, use a shell.

Our ABS 13042-95 is 130×42 mm and 9.5 mm thick, 40 g, moulded in ABS, ASA or PC with an aluminium-on-PET antenna and rated IP65. It has a 7×5 mm rivet hole and a 7.5×2 mm cable-tie slot, mounts with adhesive or screws, can be printed, and comes in white, black, green, orange, yellow or grey on request.

When Space Is Tight: The Small Rigid Tag

The compact SeeMore ABS 7221-06 rigid anti-metal tag

A full-size shell is overkill on smaller assets. Our ABS 7221-06 is 72×21 mm and 6.3 mm thick — 8 g, IP65, copper antenna, black as standard and customisable. It sits on a rack side rail, a distribution box or a trolley frame without catching on anything.

For Tools and Instruments: The Micro PCB Tag

The SeeMore TP2208 PCB anti-metal tag, shown on a centimetre grid to indicate its size

For tools, instruments and small metal parts, our TP2208 measures 22×8×2.5 mm: FR-4 substrate, copper antenna with gold plating, NXP Ucode 8 chip, about 2 m read range on metal at 30 dBm handheld power, IP65, -20 °C to +80 °C, fixed with 3M 300LSE adhesive or a screw. A small tag reads short — plan the antenna around that, not around the datasheet of a bigger tag.

Six Dimensions That Actually Decide

Flexible anti-metal tag (left) versus rigid ABS anti-metal tag (right)

·         Read range — flexible FL7030 reaches 12 m on metal with a fixed reader. Rigid shells are built for durability first, so treat range as a result of size and chip, not a target.

·         Size — 130×42 mm down to 22×8 mm. A bigger antenna captures more energy and reads further.

·         Surface curvature — flexible conforms to gentle curves; rigid needs a flat patch.

·         Weather and ingress — flexible is rated -20 °C to +75 °C; rigid shells add IP65, and TP2208 runs -20 °C to +80 °C.

·         Mounting — adhesive, screw, rivet or cable tie.

·         Asset type — IT and office equipment points to flexible; outdoor, vehicles, containers and heavy plant point to rigid.

Mounting Decides Whether a Tag Survives Year Two

Structure chart of the SeeMore ABS 13042-95 hard tag, showing through-holes for screw or rivet fixing

·         Adhesive — fastest, and fine for indoor IT assets on clean, flat metal. Surface preparation matters more than the glue.

·         Screw or rivet — the default for rigid shells on vehicles, containers and plant. The 13042-95 has a 7×5 mm rivet hole for exactly this.

·         Cable tie — for pipes, rails and anything round; the same tag carries a 7.5×2 mm slot.

·         Micro tags — TP2208 takes 3M 300LSE adhesive or a screw.

Whichever you choose, mount every tag of the same asset type in the same place. Consistency is what makes a read zone predictable.

Where the Readers Fit In

Tags are half the system. In a fixed asset deployment they are read at three points: a doorway portal such as our Aura GR14752, multi-port fixed readers Symo FR34A/54A driving four to eight antennas in the room, and a desktop reader such as the Aura A032 at the check-out counter. Choose the tag for the asset and its surface; choose the reader for the read zone.

Unsure on a mixed asset list? Most deployments settle on two types — flexible for IT and office equipment, rigid for anything that leaves the building. Send us your asset list and photos of the mounting surfaces, and we will propose a tag mix and ship samples: talk to our team.