Flexible automation concepts for data-driven battery cell production

Electromobility is one of the key global trends in the automotive industry. More and more car manufacturers are turning to electric vehicles to reduce the CO2 emissions of their fleets. Efficient battery cell production is crucial to the success of electromobility. This is why car manufacturers themselves are increasingly becoming battery manufacturers alongside major suppliers. While automotive battery production is still concentrated in Asia, Western companies have also invested in developing their own battery production capacities in recent years.

Short innovation cycles

The processes and technologies for battery cell production will continue to evolve in the coming years. With new raw materials, advanced mixing and coating processes or alternative methods for calendering and winding, changes will keep coming. Battery cell manufacturers who want to prepare their existing and future production systems for this dynamic phase and significantly shortened innovation cycles need powerful automation partners whose solutions support digital transformation to enable modular, flexible system concepts. With its robust portfolio, TURCK has been one of the leading automation partners for the automotive industry worldwide for decades; and today, the most successful battery manufacturers also rely on TURCK technology to make their production systems flexible and future-proof with data-driven process optimization.

Three pillars for efficient production

Contactless RFID identification technology helps increase the output of existing systems while improving process reliability and product quality. Condition monitoring solutions detect problems at an early stage, enabling predictive maintenance that lastingly increases availability and, in turn, overall equipment efficiency (OEE). Above all, decentralized automation technology with robust, non-cabinet-bound IP67 systems makes it easier to set up modular production systems where machines can later be regrouped or capacities relocated.

Traceability: The energy density of batteries is comparable to that of explosives, which means defective batteries can be highly dangerous. A production process that automatically documents every raw material, every product and every production step guarantees battery cells of the highest quality. Track-and-trace systems ensure error-free production. TURCK has nearly 20 years of experience with HF and UHF RFID solutions in production environments. Few other suppliers can offer such a broad RFID portfolio and special technologies such as HF bus mode.

Overall equipment efficiency (OEE): The manufacturing cost of a product and the profitability of production depend heavily on the availability of its production system. This is why improving OEE is a key goal in battery production. The aim is to minimize unplanned machine downtime and avoid material shortages wherever possible. Condition monitoring systems can be used to monitor machine states and plan maintenance proactively, while RFID identification technology improves the data basis for material procurement.

Flexibility: With the many different battery applications, the number of battery cell types will increase. This means production plants should be prepared for future adjustments both mechanically and in terms of automation. Modular system concepts are key to increasing flexibility. Decentralized I/O and control solutions in IP67, combined with fast, flexible Industrial Ethernet communication, allow system modules to be quickly rearranged. Controlled by decentralized PLCs and safety controllers, factory acceptance tests can even be carried out at the manufacturer's site, reducing commissioning time for the overall system.

The following examples show how TURCK solutions support battery manufacturers.

IO-Link fluid sensors monitor calendering

One of the most critical process steps in the production of lithium-ion battery cells is calendering. The copper foil (anode) or aluminum foil (cathode) coated on both sides is compressed by several rotating pairs of heated rollers, then rolled up and transferred to the next process step. Hydraulically driven roller pairs generate a precisely defined pressure that must always be maintained. Any deviation from this reduces the quality and performance of the battery cells. Excessive pressure can even damage the substrate.

A complete IO-Link solution consisting of sensors and matching infrastructure monitors the interaction of all process components, ensuring optimal calendering. The TBENL4-8IOL from TURCK serves as the IO-Link master. The compact Ethernet multiprotocol I/O module has eight IO-Link master channels. Measurement and monitoring are handled by robust pressure and temperature sensors from the TURCK Fluid+ product series, installed inside the hydraulic system. The PS+ pressure sensors ensure constant, optimal pressure so that the substrate has a uniform surface structure and the required porosity. The TS+ temperature sensors monitor the temperature not only of the rollers, but also of the fluid that heats them. IO-Link enables easy parameterization and commissioning, as well as replacement of devices in battery production. To prevent unplanned breaks in production, empty reels of substrate foil must be detected in good time. This requires continuous measurement of the roller diameter using RU80D ultrasonic sensors from TURCK.

HF bus mode ensures the quality of lithium-ion batteries

When assembling battery modules from individual cells, they are welded to an aluminum strip. The quality of the weld points is critical for the quality of the battery and is therefore tested after welding. The result is written directly to the tag mounted under the product carrier of the module. In total, the production line has around 35 read/write positions, which can be quite expensive with standard RFID systems. RFID via IO-Link would be an alternative, but is usually too slow due to its limited bandwidth.

With Turck's HF bus mode, up to 32 read/write devices can be connected in series to a single port of the RFID interface, significantly reducing the cost per read/write position. Thanks to the high bandwidth of bus operation, the production line can maintain its original speed. Another advantage is that each read/write head can read both EPROM and FRAM tags. The reading of the tags is triggered by an inductive sensor. If multiple tags are in the air interface of different read/write heads at the same time, the PLC creates a buffer to execute commands for the different read/write heads sequentially. In addition, the trigger sensor helps to detect errors: if a tag cannot be read after being triggered, this indicates that it is defective. RFID devices and trigger sensors are connected directly to the

TBEN-S2-2RFID-4DXP. The IP67 interface communicates with the PLC via Profinet, but as a multiprotocol device, it can also be used in Ethernet/IP or Modbus TCP networks without user intervention.

RFID tracking via OPC UA

Production steps are not always managed by a PLC or a control system, but are often created directly in the ERP system. As a result identification systems must also be able to communicate directly with the ERP system. OPC UA has proven to be the ideal interface for this, as the standard is "understood" by IT systems as well as by OT machines and systems. Using the TBEN-L-4RFID interface from TURCK, data from the robust IP67 TNLR-Q80 read/write heads is transmitted to the ERP system via OPC UA.

RFID communication in metal environments can be error-prone due to possible reflections, so special tags for mounting on metal ensure reliable identification processes. Only the ID of the tag is read, and the correct information is assigned and supplemented using a database. As a full-service supplier, TURCK offers a complete system from a single source: from tags, read/write devices and connection cables to RFID interfaces and expert support. This approach prevents communication problems caused by cross-manufacturer solutions.