Workpiece Carrier Identification in Rear Vent Production

Automotive supplier EuWe identifies workpiece carriers on the manufacturing islands of a production machine for rear vents with Turck's BL ident RFID system

Linked production processes in special machines have disadvantages, as a stop at one station results almost immediately in the shutdown of the entire machine. Intelligent buffer sections can ensure a continuous flow of production but can only be implemented effectively with the identification of the workpieces. Automotive supplier EuWe Eugen Wexler GmbH & Co. KG has implemented this in a new production plant for rear vents – with Turck's BL ident RFID system.

For EuWe, the compact rectangular design is a decisive benefit of the Turck read/write head
The view from below onto the workpiece carrier shows the centrally mounted tag and the four rear vents
The BL20 gateway in the control cabinet brings the RFID data via Profinet to the controller
The read/write head is mounted in the middle of the workpiece carrier fixing

Rear vents for BMW

The company EuWe started in 2014 to expand the existing production with another special machine for manufacturing rear vents for BMW. The system was called island manufacturing since it consists of several individual manufacturing islands. An injection molding machine for producing the blanks is located at the beginning of the process. A conveyor belt transports the blanks to the ultrasonic welding, where the flaps are fixed to the semi-finished product. A camera at the next station checks for welding faults. At the last process step, a robot applies sealing foam to the turned vents. A camera with special lighting on the robot arm checks the shape, consistency and volume of the sealing foam at last.

Disadvantages of linked systems

The question was also raised as to the most suitable method of identifying the workpiece carriers in the process. Automation technician Robert Ullmann had already gained experience in the identification of workpiece carriers in an existing plant. In the previous plant, EuWe had implemented a linked system using conventional proximity switches. However, the chain of workpiece carriers could not be interrupted. This was the biggest disadvantage of linked systems. A buffer section that can compensate for delays in the process is not possible. Due to this experience, Ullmann also recommended the implementation of a workpiece carrier identification system with RFID for the second rear vent production plant.

Compact design simplifies mounting

“We looked at another RFID supplier besides Turck. However, this supplier only had RFID read/write heads in a cylindrical design in its range,” Ullmann describes one of the reasons for choosing Turck. EuWe uses a flat rectangular TN-Q14-0.15-RS4.47T read/write head that can be mounted optimally in the middle of the fixings at the production islands. The circular TW-R50-B128 tag was mounted centrally on the material carrier.

Simple integration in the controller

“The integration of the Turck RFID system in the controller was very easy. We didn't need to integrate any special program blocks in the PLC software in order to translate the RFID language into the language of the controller. I could operate the interface of the controller directly. The information is simply written to the PLC output and then lands on the workpiece carrier,” Ullmann praises the integration of BL ident RFID in the Siemens S7 controller.

The RFID system identifies each workpiece carrier in the process eight times. The PLC writes faulty processing steps to a database which links the entry with the corresponding workpiece carrier and the position of the rear vent on the carrier. The data reaches the S7 controller via Turck's BL20 multiprotocol gateway and Profinet.

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