UHF RFID Versus UHF RTLS

Many companies new to UHF (Ultra High Frequency) RFID (Radio Frequency Identification) confuse it with UHF RTLS (Real Time Location Systems). While both indeed do use UHF RFID, they differ substantially in what they can actually do for you in your business.

Many companies new to UHF (Ultra High Frequency) RFID (Radio Frequency Identification) confuse it with UHF RTLS (Real Time Location Systems). While both indeed do use UHF RFID, they differ substantially in what they can actually do for you in your business.
UHF RFID

Standard UHF RFID systems can see multiple tags on equipment and products up to several meters away, if set up properly. With emphasis on “set up properly.” While UHF RFID works quite well, its unique characteristics require testing in the environment where it will be used to ensure success.

UHF RFID has several purposes:

    • To see if an item has passed a certain point, commonly known as a choke point. Examples of this are items being loaded on or off a trailer at a shipping door or items passing from one area to another in a plant.
    • To verify if something is within a certain area when using a scanning device, such as a handheld reader. If one is scanning shelves of parts or equipment, it will help locate those items.
    • To track usage of equipment in MIS systems.
    • The tags can also have data written to them if needed.

The big thing that UHF RFID cannot do is effectively track the exact location of something at any given time in a cost-effective manner. Generally, UHF RFID uses what are called passive tags for the antennas to read. These tags have no battery and get energized from the antenna signal. If you placed enough antennas all over a facility and enough of these tags, then you could possibly locate something within a certain proximity, but not exactly, and this is hardly cost effective.

UHF Real Time Location Systems (RTLSs)

RTLS, on the other hand, are specifically designed to pinpoint the location of anything with a tag or transponder on it. In fact, RTLS refers to any system that can accurately determine an item or person’s location. An important aspect of RTLS is how frequently assets must be tracked. This data can be used in different ways depending on the application. For example, some RTLS applications only need timestamps when an asset passes through an area, while others require much higher visibility, requiring constant updating of time data.

An ideal RTLS can accurately locate, track, and manage assets, inventory, or people, and help companies make knowledgeable decisions based on collected location data.

Like regular UHF RFID, RTLS can use passive or active tags (tags with batteries), but they use triangulation of multiple antennas to determine the location of an object or person. The strength of the signal at each antenna, combined with the software attached to the antennas, allows the identification of the location of an object or person within less than 1 meter.

The system you choose depends on the needs at your location. They both work quite well when implemented properly by trained professionals.

Also, due to the inherent properties of ultra-high frequencies used in UHF RFID technology and RTLS, you should perform a feasibility study that actually tests the system in the real world environment of the plant prior to implementing these systems in any application.

Lithium Ion Battery Manufacturing – RFID is on a Roll

With more and more consumers setting their sights on ‘Drive Electric,’ manufacturers must prepare themselves for alternative solutions to combustion engines. This change will no doubt require an alternative automation strategy for our electric futures.

The battery

The driving force behind these new electric vehicles is, of course, the battery. With this new wave of electric vehicles, the lithium ion battery manufacturing sector is growing exponentially, creating a significant need for traceability and tracking throughout the manufacturing processes.

Battery manufacturing is classified into three major production areas:

    1. Electrode manufacturing
    2. Cell assembly
    3. Finishing formation, aging and testing

These processes require flexible and efficient automation solutions to produce high quality batteries effectively. As such, there are numerous areas that can benefit from RFID and/or code reading solutions. One of the biggest of these is the electrode manufacturing process, specifically on the individual mother and daughter electrode rolls. This is a great application for UHF (Ultra-High Frequency) RFID.

The Need for RFID

The electrode formation process involves numerous production steps, including mixing, coating, calendaring, drying, slitting and vacuum drying. Each machine process generally begins with unwinding turrets and ends with winding ones. A roll-to-roll process.

Two of the three primary components of the lithium ion battery, both the anode and cathode electrode, are produced on rolls and require identification, process step validation and full traceability all the way through the plant.

During the slitting process both larger mother rolls are unwound and sliced into multiple, smaller daughter rolls. These mother and daughter rolls must also be tracked and traced through the remaining processes, into storage and ultimately, into a battery cell.

Solution

Working with our battery customers and understanding their process needs, a UHF RFID tag was developed specifically to withstand the electrode production environment. Having a tag that can withstand a high temperature range is crucial, particularly in the vacuum drying lines. This tag is capable of surviving cycling applications with temperatures up to 235 °C. Its small form factor is ideal for recess mounting in the anode and cathode roll cores with an operating range reaching 4 meters.

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The tag embedded in the roll core paired with an RFID processor and UHF antenna provides all the necessary hardware in supporting battery plants to achieve their desired objective of tracking all production steps. Customers not only have the option of obtaining read/writes, via fixed antennas at the turrets, but also handheld ones for all storage locations — from goods receiving to daughter coil storage racks within a plant.

This UHF RFID system allows for tracking from the initial electrode coils from goods received in the warehouse, through the multiple machines in the electrode manufacturing process, into the storage areas, and to the battery cell assembly going in the electric vehicle — ultimately linking all battery cells back to a particular daughter roll, and back to its initial mother roll. RFID is on a Roll!

UHF making a big impact on manufacturing

RFIDUltra-High Frequency (UHF) RFID is quickly becoming the go-to identification system for flexible manufacturing lines around the world. While it was once considered to be a system designed primarily for distribution centers and retail stores, UHF technology has evolved to meet the rigors of the manufacturing environment.

Not long ago I was in a discussion with one of my customers who had been using RFID for almost 25 years. He was caught in a tough spot because he had an application which required reading tags from as little as six inches away to as far as two feet away. The HF system he had could easily meet his needs for the six inch read range, but reading at two feet away limited him to using UHF. When I explained that, his bewildered look indicated to me he was reluctant to consider UHF as a real option. He went on to explain that about ten years prior he conducted tests in his plant with UHF and found a host of limitations with the technology. His main concern was how the operators’ two-way radios interfered with the UHF operating frequency of 902-928MHz. Having heard this from other manufacturing organizations who were early adopters I knew right away that he wasn’t aware of how the technology has evolved over the last decade.

Frequency hopping has pretty much eliminated interference with other radio signals. In addition to overcoming radio interference, being able to read and write to tags which are mounted on or near metal and liquids has become a reality with recent advancements. These improvements have led to more flexible read ranges which are a requirement in today’s flexible manufacturing applications.

In a nutshell, the demands of flexible manufacturing have spurred advancements in the process as well as the supporting technology. As it applies to identification of parts or pallets in the manufacturing process, the flexibility of UHF RFID enables manufacturers to gain visibility in their process and provides actionable data that is used to make complex business decisions.

You can learn more about the technology in Balluff’s white paper, What Makes RFID Systems Industrial Strength? or by visiting our website at www.balluff.us