HF and UHF RFID transponder types compared.
In the 1990s, LF (low frequency) RFID transponders were first used, mainly for automatic garment dispensers. These have been replaced by HF (high frequency) RFID transponders from the year 2000. In 2008, the introduction of UHF RFID began and the Wozabal Group was a pioneer in the industry.
RFID HF Transponder "Blue Tag" von HID Global
RFID UHF Transponder C10 von HID Global
30-70 mm length, 10-15 mm wide
ID codierbar, Kennwortschutz
15-40 cm (5" to 1 ft) reading range
4-7 m (12-20 ft) reading range
Multiread with 10x speed compared to HF
Frequency: 13,56 MHz
Standard: ISO 18000-3
Requency: 865–868 MHz (Europe),
902–928 MHz (North America)
Standard: ISO 18000-6C
fewer false readings ("leakage") due to shorter range, very resistant, readability in wet condition
Reading in bulk, longer range, cheaper antennas, encoding possible
Hanging Uniform Dispensers, Uniform Rental, Swobs
Flat linen, Uniforms in SMART-Rooms, Uniform Rental
- HF RFID will continue to have a medium-term role in uniform rental, especially in hanging automatic garment dispensers and in existing applications where a switch to UHF is not worth it.
- UHF RFID also has significant advantages for workwear. Proper installation allows individual garments to be read equally well as with HF. Internationally, many companies are therefore switching from barcode directly to UHF RFID.
- As of 2022, UHF RFID is used by about 60% of laundries in German-speaking countries (Austria > 90%) and will become more and more common in the flat linen sector.
- As of 2022: A working group on digitization is meeting at the DTV (similar to the TRSA in Germany). Important recommendations regarding the labeling of textiles and the improvement of the procurement process are being worked out. However, the discussion is not yet finished, as some software manufacturers are very challenged with the implementation of the GTIN.
On YouTube there is a playlist on the topic: link to playlist
- Interesting technological developments regarding transponders, hardware and software. More on my YouTube channel: link to YouTube channel
Layout of a UHF RFID transponder
The UHF RFID transponder consists of
- One chip (which is effectively produced by only one manufacturer),
- a housing with the primary antenna and
- of a secondary antenna.
The chip with a primary antenna is readable but has only a short range of a few inches. Finally, the secundary antenna achieves a range of up to 7 meters (20 feet).
RFID UHF Tag für Textilien und Chip
The functionality of the transponders is standardized and every UHF RFID transponder is therefore compatible.
The differences between the manufacturers are found in
- the characteristics of the primary antenna,
- the ruggedness of the transponder's housing,
- the quality and functionality of the secondary antenna,
- the size and the design,
- the policy regarding the password protection and the encoding of the tag,
- the reproducible quality in production and
- the delivery capability
In most cases, the chip itself is sourced from the same manufacturer.
Functionality of UHF RFID transponder
The UHF RFID transponder used in the laundry is a passive chip. Unlike active chips or semi-active chips, the transponder requires energy from the antenna or reader to be activated. The tag sends back a modified signal.
Funktionsweise von UHF RFID Transpondern
UHF RFID transponders can execute commands: (HF tags do not have this function)
- Encoding of the transponder
- "Kill" or permanent destruction of the transponder
- Setting a password for writing or reading the transponder
The simple reading of the ID of the transponder takes place within milliseconds virtually in real time, so that an entire container with over 200 pieces can be read within 10-15 seconds.
Encoding is much slower and can take 30-120 seconds per container. (which is still relatively fast compared to initializing each item manually).
The functionality of UHF RFID systems was standardized by GS1 in 2004 and published as EPC UHF Gen 2 in the ISO/IEC 18000-6C standard.
Factors affecting the range of RFID UHF tags
In order to successfully implement UHF RFID technology, a sound understanding of the limitations is important. Used correctly, this technology can be implemented very well and very stable. However, where there is a lot of light, there is also a lot of shadow.
The major challenges are:
- not a 100% read rate for a single reading.
- limited reading rate in hot or wet conditions.
- Water absorbs the UHF frequency and wet transponders are not readable in contrary to HF.
- Misreading, i.e. unintentional reading of transponders ("leakage")
In the following, I would like to go into detail about the causes.
The reading distance of the transponder is dependent on direction
Leseradius unterschiedlich je nach Ausrichtung der RFID Antenne zum UHF Tag
The reading range is greatest when the largest possible surface area of the transponder is facing the antenna.
If it is read at an angle or from the side, the range is significantly reduced. (s. diagram)
- either move the textiles,
- install several antennas or
- incorporate deliberate reflections.
- make sure that the chip is not attached to a fold of the textile.
UHF RFID Tag im "Blinden Fleck" der RFID Antenne
The wavelength for UHF RFID is around 30-35 cm (1 ft).
Every 30 cm (1 ft), therefore, there is a risk that the transponder will not be activated because it is located at the zero point of the wave.
The reader can prevent this blind spot by changing the frequency. However, this requires a longer reading time.
- either move the textiles,
- install several antennas,
- incorporate deliberate reflection or
- wait for the frequency modulation of the reader.
Transponders interfere with each other
eingeschränkte Leserate bei Wäschestapel mit vielen Tags direkt übereinander
Each transponder has an antenna and is activated simultaneously by the reader. This means that the transponders can interfere with each other.
- Especially with small items, do not always place the transponders in exactly the same position.
Misreadings due to deflection of the signal
UHF Fehllesung durch Ablenkung des UHF Signals durch Metalle, Menschen, Wände etc.
Metal, a wall, a ceiling or even a person can deflect the signal and tags that are nearby are suddenly read unintentionally.
This problem occurs especially when the Reader is constantly running at maximum power.
- Workplace design by an expert
- Using a smart reader that a) requires less power and b) is not on all the time.
Limited reading performance with hot textiles
eingeschränkte Reichweite bei heißer Wäsche, z.T. wird der UHF RFID Chip temporär deaktiviert.
Most UHF RFID transponders "survive" ironing at around 200°C (400 F), heat-sealing at 220°C (430 F) and sterilization at 134°C (280 F).
However, the heat can completely or partially deactivate the transponders for a short time.
HID has already proven that scanning is nevertheless possible by installing a reading point after the ironer and before the folding machine.
- Thoroughly test the transponders with regard to the effect of the temperature.
- If necessary, installation by an expert
Limited read performance in wet conditions
UHF RFID hat eine eingeschränkte Reichweite bei nasser Wäsche
Unlike LF and HF, UHF RFID cannot be read through water. However, textiles after the press or centrifuge with residual moisture and normally soiled laundry can be read very well.
There are differences between different transponders regarding the readability in wet conditions.
- Do not install reading points when textiles are completely wet.
- Test the transponders used for this application.
- Switch to HF technology if necessary
Limited reading performance with metal
UHF RFID hat eine eingeschränkte Leserate bei Metall
Metal shields or interferes with the antenna of the transponder. (even if it is behind the tag)
- Sufficiently test containers in use in connection with the UHF installation. (usually metal mesh containers are not a problem).
- Installation and workplace design by an expert.
... the good news
Through good design of the workstations or reading points and the use of modern hardware, read rates of well over 99% can be achieved.
Over the entire process in the laundry, 99.95% of all transponders have already been read and documented by external expert reports.
Quality requirements for the purchase of UHF RFID chips
It is important to buy the right quality of transponders from the beginning, otherwise you will have a more serious problem in the implementation. The replacement of transponders costs many times more and must be amortized within a shorter remaining life of the textile.
When making a purchase decision, consider:
- the actual lifetime of the UHF transponders
- the actual process fitness in YOUR plant
- for the healthcare: MRI Compatibility
- a uniform quality of all transponders (no deviations)
- the policy regarding encoding and password protection
- Delivery terms of the manufacturer
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Actual durability of the UHF RFID transponders
There are significant differences between individual manufacturers in the actual service life - due to the design of the housing and the quality of the secondary antenna.
It is important to test both the function of the chip and that of the antenna at the end of the life cycle. For the purpose of this test, the entire washing process needs to be run through.
The result may thus be:
- The transponder is fully functional, has approximately the same reading rate as at the beginning and is therefore fully functional for longer than the service live of the textile. (=realistic target)
- The transponder has only a limited reading range. In this case, the secondary antenna is probably damaged.
- The transponder no longer works (total failure). This is probably due to damage to the chip.
Since the reprocessing processes are different and no standardized external test procedure has been developed to date (analogous to the quality label), it is advisable to carry out the tests yourself in your own plant.
Subsequently, it makes sense to define standards for the requirements of UHF RFID transponders in the industry and to prescribe these test criteria to the manufacturers.
Actual process fitness in the laundry
Transponders differ in
- the reading range
- the ability to read single items without leakage (reading wrong pieces)
- the readability in wet condition
- the readability of a stack of textiles
It is therefore important to qualify the transponders for your own process so that the requirements of all workstations and applications are met.
For process suitability, it must be tested for each read point whether
- the reading rate meets the requirements and whether it
- there are increased misreadings. ("leakage")
ATTENTION: some installations are extremely optimized for a transponder from a particular manufacturer. In this case, the laundry becomes dependent on one supplier. A good UHF RFID installation is characterized by being robust to any variations in individual transponder performance criteria.
MRI Compatibility (Healthcare)
The secondary antenna of the transponder can cause considerable interference with MRI scans. This primarily affects patient gowns, pajamas, and sheets that are used during the examination. Since patients are usually not supposed to be changed, and in some cases textiles from the wards are also used in the MRI, ALL tags need to be MRI complient.
There are transponders that are MRI compatible and do not cause any significant interference. These are preferable in the case of hospital supply.
The production and assembly of the transponders are either done manually or fully automated. Accordingly, there may also be deviations in the manufacturing process.
Therefore, consistent quality and sound quality management by the manufacturer are crucial.
Ways to evaluate this are:
- Certification of the manufacturer
- Obtain references
- Audit on site
Logistics service of the manufacturer
The administration of the transponders with the various suppliers can be very time-consuming. As a result, some manufacturers send the transponders directly to the textile manufacturers and thus help simplify the entire supply chain.
In this case, however, each textile service company sends the transponders to the textile manufacturers or via the manufacturer.
When the quality of the transponders is standardized, we hope that the textile producers will purchase the transponders and sell the textile with the transponder included. This would represent a significant simplification for all parties involved.
The market is currently very much on the move. Many large companies in the textile service sector and also hotel chains are making decisions in favor of UHF RFID technology.
It therefore happens that manufacturers repeatedly reach the limits of their capacity.
It is therefore important to have framework agreements with corresponding obligations to ensure availability and, if necessary, to list a second supplier.
Fortunately, the purchase price for transponders reduces from year to year. When negotiating framework agreements, it is therefore necessary to weigh up between a more favorable price due to a higher volume and the chance of more favorable prices in 1-2 years.
Testing of UHF RFID transponders
UHF transponders are used in large numbers in many areas such as retail, the automotive industry, etc.. However, tests for the washing of semiconductors are not yet standardized.
There are some initial concepts here and it would make sense for the industry association to moderate the development of a standard. One test institute that has already carried out tests is the EECC (European EPC Competence Center).
However, it will be necessary in any case to qualify the transponders for your own requirements.
I have created detailed checklists and recommendations for testing UHF transponders. You can download this with the following link ...
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The DTV's Digitization Working Group is currently working on recommendations for the following topics:
- Encoding of the UHF RFID transponders with an SGTIN
- Definition of the minimum requirements for master data in order to standardize the cooperation between textile manufacturers and the textile service or also between textile service companies and their customers.
- Standardized processes in the supply chain
First results have been presented, but due to the pandemic the final recommendation has been delayed.
Attaching UHF RFID transponders to textiles
The types of attachment are:
- Sewing in by the textile manufacturer (usually in the hem).
This is often the most cost-effective option, as many manufacturers do not charge additional costs and it does not affect the appearance.
- Sewing on with a pouch or a textile label, usually with logo.
This is by far the most expensive option, as the pouch costs money, the chip has to be inserted into the pouch, and sewing on - even with an automatic machine - is time-consuming with an hourly output of only 60-100 parts per MA hour. Additional costs of 25 cents and more are therefore to be expected. On the other hand, a pouch with a logo consistently represents added value.
"Heatsealable tags" or transponders for patching are a very good alternative. The hourly output is up to 200 pieces and the durability is positively tested.
Important aspects to consider:
- Follow the manufacturer's instructions.
- Especially in the case of small items, the transponders should always be placed in slightly different locations, if possible, so that they do not interfere with each other when reading a stack.
- Do not attach a tag to folds, as this also reduces readability.
- When the manufacturer sews in the transponder, it must be ensured that the transponder is not bent, sewn over the chip or even the secondary antenna is cut off. (all already happened and partly difficult to recognize, because the transponder still has limited functionality).
UHF RFID and Data Privacy
This is a sensitive topic throughout and it is recommended to address this proactively. In 2003, Metro installed UHF RFID transponders on its customer cards without informing its customers, and in 2008 Deutsche Bahn received the "Big Brother Award" because it also fitted the BahnCard with a UHF RFID chip without informing its clients.
The fear is based on the fact that the transponder can be read by the employer or various snoopers without knowledge and time-lines could be derived from it. In this respect, an HF transponder has an advantage, since the shorter reading range makes concealed monitoring more difficult..
However, this is not a problem with RFID UHF laundry tags, since no reference can be made on site between the wearer of the uniform and the transponder without a database connection. This means that no personal data is involved.
UHF RFID Systems in the Laundry
Listing of already implemented applications:
Installation of multiple antennas that collectively capture over 99% of soiled textiles and generate the order based on the soil count.
IMPORTANT: UHF RFID is no substitute for good operational management and adherence to the wash schedule is even more important.
Batch documentation for PPE, surgical drapes and gowns
Reading in all pieces of a batch so that the batch records can be referenced to every piece in the batch.
Merging of individual uniforms with the tag of the hanger. (At the feeding station, at the quality check-point, or at a singularization similar to reading points with HF technology. (Only experienced technicians can implement this without risking leakage)
Reading of single items at the towel folder
Reading of each individual piece either during feeding. Pieces without transponders are rejected, as well as parts that should be rejected according to the Laundry software. (reclamation parts, end-of-life).
The implementation must be checked per machine type, but can usually be done without intervention in the folding machine. An interface is not always necessary, but advantageous.
Reading of single items at the ironer
Reading of each individual piece either during feeding or before the folding machine. Pieces without transponders are rejected, as well as parts that should be rejected according to the Laundry software. (reclamation parts, end-of-life).
The implementation must be checked per model, but can usually be implemented with dry contacts to the existing reject buttons.
This has already been successfully implemented several times, although the heat after the ironer is a challenge.
Parts tagged with UHF RFID can be sorted in real time, especially if they are encoded with the part number (SGTIN). Already successfully implemented.
However, it is important that the process also works without UHF RFID, otherwise the system cannot work with non-chipped parts. (own experience!)
fully automatic or manual
The items in a stack are checked to see if they contain the right number and the right items, then they are combined to a virtual stack.
At this point, picking into the customer's order can also take place immediately.
In a cabin, 98-99% of a container's transponders can be read within 15 seconds.
Advantages: optimized reading and no false readings ("leakage").
To achieve 100%, a multi-step process is necessary.
The containers are pushed through an "archway" with UHF RFID antennas. This is very fast and can deliver relatively good read rates.(+/-95%)
The challenges are misreading between different containers and non-reproducible conditions in case the containers are pushed manually.
Processing surgical drapes and gowns (medical devices), Sterilization
The transponder can be autoclaved (273 F or 134°C). At the assembly of the pack each piece is merged with the sterile pack. Before sterilization the packs are merged with the sterile batch.
Production data acquisition, process visualization
Practically as a "by-product", implementation of data acquisition and visualization can be carried out independently of the machine manufacturer.
Incoming goods control / procurement process
The incoming goods inspection can best be automated via a cabin. In the course of this, the articles can be encoded or recoded.
The "Digitization" working group is developing a process description from the order to the order confirmation, the delivery bill, the invoice, and the goods receipt.
Data is exchanged electronically throughout the process. This saves a lot of work and eliminates errors.
Note: this is technically possible, but still "dreams of the future", as the GTIN has not yet been implemented.
Inventory in the plant for textile, at the customer's premises etc.
Inventory of textiles, new and used goods in the plant, as well as any other inventory.
Taking inventory with the handheld antenna is relatively fast (approx. 5 minutes per area) and has a relatively high read rate (95-98%). However, it depends on the user and is therefore difficult to standardize.
Securing of exits in the plant or at the customer's site
Containers equipped with a transponder can be read with the same antennas. If necessary, a 2nd active transponder can also be considered so that a truck can always be read out as a whole without much effort.
UHF RFID transponders for the resident laundry are still at the concept stage. There are already some laundries and nursing home groups using UHF for resident laundry. The challenge is the payback of the transponder on the short time of use of the garment and the tagging of small items (e.g. socks, underwear).
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UHF RFID systems in hotel and hospital
Inventory at the customer
In 2-10 minutes per laundry room, a sufficiently accurate inventory can be taken with the handheld antenna.
This can be the basis for orders and/or shrinkage calculations.
Uniform Service with "SMART-Rooms"
The customer's employee gains access with his ID card and picks up the required clothing from the shelf. The employee is credited with the taken garment when leaving. After dropping the used uniform, the employee receives a new credit.
Management of the Inhouse logistics
In large hotels or hospitals, the linen center can be managed with UHF RFID.
Securing exits in the hotel or hospital.
Cost of UHF RFID
The costs of UHF RFID are divided into the acquisition costs of the hardware and software, the project costs and the operating costs, which consist mainly of the transponders and software licenses.
Investment in UHF RFID hardware
Since the UHF RFID hardware is significantly cheaper than the HF RFID hardware, the investment amounts to about $10,000 for a small installation and $100,000 for a laundry with a daily output of 20-30 tons (without process automation), which is very manageable and pays for itself immediately through the reduction in linen purchases
Cost of UHF RFID Project
A RFID project includes the following project phases:
- Integration of RFID technology into the business model (strategy and marketing)
- Planning of the installation and technical implementation
- Design of individual workstations, if necessary
- Process organization
- Retrofit of textiles, if necessary
- Training of employees
- Conversion of customers
The costs for the project are extremely variable and can - from our own experience - range from very low expenditures ($ 10,000 to $ 20,000) to six-figure sums per plant.
What are the cost drivers in an RFID project?
- Batch-Processes (Customer-specific processes) are easier to migrate than Pool-Processes
- Retrofit is more expensive than purchasing new textiles with UHF tags.
- High degree of automatization
- Half-hearted implementations that cost money and bring no benefits
Therefore, to save costs is the recommendation:
- make strategic decisions and not put them on the back burner.
- start with a pilot project as soon as possible, as this is much cheaper than a forced conversion due to demand from current or potential customers.
- start equipping new textiles with UHF RFID transponders as soon as possible.
- involve experts who already have experience - it is always more cost-effective to learn from the successes and even more so from the mistakes of others.
- Sound project management
Cost of UHF RFID transponders
The actual costs must always be considered in relation to the price of the respective service:
- Flat linen: 1-2% of sales (assumption: 15% of sales for linen purchase, takes cost about 7-10% of linen purchase).
- Uniforms: 0.4% of sales (assumption: 20% of sales for the purchase of garments, tags make about 2% cost of uniform purchasing).
- PPE: 0.15% of sales (assumption: 30% of sales for uniform purchase; tags amount to 0.5% of PPE purchase).
This is, of course, an approximate calculation and can be different in every company. However, it can be seen that RFID UHF is very interesting for garments and especially also for PPE, and that many advantages can be implemented with relatively little expense.
What is the return on investment?
- Customer benefits - elimination of ordering effort, no redundant inventory, customer-specific items easier to implement, improvement in delivery quality
- More sales due to new billing methods
- 0.5-2% of sales savings due to less shrinkage or charging for losses
- Productivity increase of 10-30% depending on layout and process.
- Savings of 1-3 days of textile inventory in the plant in case of pool processes
- in case of rental, significant savings in tied-up textile capital at the customer (probably 30%)
- higher delivery capacity results in higher stability in the fleet (no extra deliveries)
The calculation must be analyzed in detail per project and cannot be generalized.
Here, too, there is a difference between customerspecific (or batch) processes and pool processes. Pool processes have significantly higher project costs, but benefit immensely more from implementation than customer-related processes.
In the end, it is also expensive if you are the last one. Imagine if there was another insurance company that didn't take claims into account in its premium. This insurance company can not offer such competitive prices and quickly there will be all the customers with a bad claims history. Thus, if you are the last one, you are in deep trouble...
Textile Service 4.0, IoT
This technology thus enables many innovations in the industry. After OPLs (customer-owned laundry), contract laundry (COG) and textile rental, one can therefore rightly speak of Textile Service 4.0.
With UHF RFID as a basis, business processes can be redesigned:
- new ordering processes
- Significantly improved transparency
- new possibilities of billing and contractual terms with the customer
- new opportunities in marketing
In the future, readers will increasingly become SMART readers equipped with their own processor. UHF RFID is thus part of the implementation of "Internet-of-things" or IoT.
The future has already begun ...
UHF RFID is a significant advance over HF and will also replace existing HF applications in the long term.
UHF RFID is almost certainly a key technology of the future.
When it comes to implementation, relevant know-how is necessary to make the most of the opportunities and avoid costly mistakes.
In essential areas, sufficient standardization of technology in textile services has not yet been implemented. This is an important task for the industry associations.
The real benefit of this technology comes when you also rethink the business model.