RFID tags will play a role in fielding the next generation of vehicles having electric powertrains.
Frank Linti • Schreiner LogiData
Many suppliers to OEMs must incorporate RFID-compatible labels on components they provide, especially in prototype construction. This is especially true for RFID labels on automotive OEM components. But OEMs sometimes have trouble using these labels due to variables in chip content configurations. So automobile manufacturers increasingly require use of standardized RFID content.
For suppliers, it pays to know a few details about the RFID tags commonly applied in automotive applications and some points to look out for.
For one thing, RFID tags can have a maximum storage of about 2 kbytes, but the RFID labels installed in vehicles have only a small storage capacity, typically 512 bits (64 characters) up to about 2,000 bits (approx. 250 characters). The arrangement of the chips on the RFID tag itself is largely standard. But the storage is typically only large enough to hold production data or, in rare cases, a defined state of the object is also transmitted.
RFID label costs typically don’t depend on whether they play a role in assembly, in logistics, or in some other use. Factors contributing to cost are generally associated with how much abuse the label must withstand, the surface it must stick to, and the type of adhesive needed to give the tag the necessary working life. Tag costs typically range between five cents and one euro per label, depending on the design and requirements.
In addition, there are only two hard and fast rules for where RFID tags are a better choice than bar codes: RFID generally is the better choice when the need is to record automatically, in bulk, from a distance or with a security requirement. RFID also offers the possibility, for example, of storing QM data on the chip. Of course, once a bar code is defined, the only way to change the data it contains is to paste another code over it.
It is also helpful to know that there are several types of standardized RFID. ISO/IEC 18000 is an international standard that describes a series of diverse RFID technologies, each using a unique frequency range. The frequencies the standard covers range from 135 kHz on the low end to 960 MHz. Of these, production and logistics RFID typically uses the UHF band, 300 MHz to 3 GHz.
Another type of RFID sometimes seen in manufacturing uses is governed by ISO/IEC 15693. It covers what are called vicinity cards which can be read from farther away (about 1.5 m). Power for the tag typically comes from the reader which beams it over the air. These systems operate at 13.56 MHz, the HF range, and typically encode information using either ASK or FSK. Typical examples are the RFID tags in public library books and in theme park passes that expire after a certain time period. But industrial RFID tags sometimes use the same technique.
It is often the case that industrial RFID applications have special needs not well suited to off-the-shelf tags. So use of RFID may entail some development work and perhaps a roll-out in a pilot project. For example, labels may require tailoring to handle challenging substrates such as metal, ESD, carbon fiber, glass or to withstand harsh heat or cold.
Many components contain iron, steel or aluminum. Metal can block electromagnetic fields and prevent readers from picking up tag data. So label manufacturers may need to build in shielding agents to prevent distortion or degradation of tag readability.
Additionally, the antenna on the tag may also need tweaking to obtain the required range, particularly when the substrate material interferes with RF reception. Special requirements such as tampering protection, personalization and encryption may also necessitate extra effort on the part of the tag supplier.
RFID labels suppliers can devise tags as needed for compatibility with specific manufacturing processes. The result can be off-the-roll processing, programming and printing to handle particular needs and manufacturing environment factors, which may include:
Production inception: Metallic components equipped with an RFID label can inform the system or machines on an array of issues, including their inspection criteria or how they should be processed downstream. Tags also facilitate handovers to various stations such as quality management, receiving and shipping departments, or to a connected external services provider.
Downstream production: When assemblies involve a large number of metallic components there will be a mix of on-metal and non-metal labels. Many of the RFID labels on metal must stick to their parts for a long time despite adverse weather. It’s best to use RFID label suppliers whose products have been tested and certified according to the relevant requirements – especially those for harsh, inclement conditions.
Painting processes: RFID labels on automotive chassis are typically applied in the body shop. The chassis then passes through numerous painting and drying processes. Temperatures may hit 230°C (446°F) depending on the painting method. Purpose-developed RFID on-metal labels can withstand such heat.
Assembly: RFID-UHF labels work better than barcode labels especially for metallic components. One reason: Readers needn’t sit close to RFID tags to retrieve their information. In contrast, bar code readers may require close proximity to scan without errors.
Logistics: Numerous work-in-progress components sit in plastic containers that must be automatically readable. Such containers need relatively high-read-range RFID labels so they can be read even while passing through a gate on a forklift. On-metal and on-plastic RFID labels are available to mitigate interference issues that can arise during handling such as electrostatic discharge.
Efficiencies stem from incorporating standardized, end-to-end readable RFID labels. RFID elements both optimize internal processes and create value across the entire production chain.
Automotive components or assemblies that must be recorded during assembly without being picked up and scanned are prime candidates for RFID. These include the engine, transmission, suspension and steering system. In addition, RFID plays a role on safety-relevant assemblies such as airbags, electrical systems, bumpers, belt systems and seats.
Finally, a point to note is that RFID implementations must observe data standards. Labels must be VDA (Germany), ANSI (US) or ISO-conformant in terms of size, design and memory. Quality is also important. Only specifically qualified materials may be used in the labels. DW