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Application background
Leineweber Group is one of the most famous clothing manufacturers in Europe, and it owns the Brax brand. Leineweber, known as an expert in the trousers industry, has also expanded its product range in recent years. The German company, which owns the Brax series Brax Golf, Eurex and Raphaela, as well as the independent brand of Braxactive, has a philosophy of “giving fashion to people who love life and are motivated.”
In order to meet the increasing demand for item sorting, Leineweber opened the central logistics center in its headquarters in Herford, eastern Westphalia, for hanging garments ten years ago. The fully automatic system can process up to 750,000 garments in seven layers. The trousers are transported along a 15-mile track in preparation for shipment in accordance with the order.
The company decided in early 2007 to update its previous control technology as part of its continuous optimization process management. “We want to replace the old S5 control system with a modern computer-based solution.” said Bernd Hettig, who is in charge of the project at Leineweber. At the same time, they hope to replace the original self-developed path track system with standardized technology. In this regard, the radio frequency identification scheme is the best choice. Leineweber handed this project to Bielefeld system integrator HMR-Rautec, which has been cooperating for many years. “We worked with Leineweber to select among the RFID solutions of multiple suppliers, and the final conclusion was that Turck’s system was the best.” said Dirk Schäning, project manager of HMR-Rautec. “From programming configuration to new control system integration, the modular design and comprehensive capabilities of the BL ident system are all impressive.” Hettig added.
System installation
It was decided that Turck would provide RFID products, and the next question was to put them into practice. Since the central logistics center cannot be shut down during the system update, careful preparation is particularly important. First, test the old system under non-stop operation. Once the test is successful, the new system can be installed. The technicians of HMR-Rautec and Leineweber must complete the installation and integration of the RFID system within one weekend.
“On Monday morning, the new system worked without error.” Bernd Hettig happily described the situation at the time, “This is the benefit of careful preparation.” The technicians installed a total of 28 read-write heads, and connected them through the Profibus interface of 7 I/O workstations. It is connected to the control system. The 1,7000 code carriers installed on the trousers transportation slide ensure that the system can accurately identify the label of each garment. The installation distance of the code carrier is only 250 mm. In this transportation system running at a speed of 34 m/min and running for 16 hours a day, the RFID system reads the UID (unique identification code of the code carrier) 130,560 times a day.
Considering that this case is purely for identification, UID is the only information in the code body. Therefore, there is no need to write other information into the code carrier. At the reading end, the system collects the RFID code value and the bar code value located on the pants packaging together. In order to realize this process, one of the two scanners reads the barcode stuck on the protective cover, and the other RFID read-write head a few centimeters away is used to scan the UID on the transportation chute.
Execute the picking command within 350 milliseconds
The system collects data and determines the transportation route of each pair of pants. According to this route plan, the slide will send the corresponding trousers out of the product queue for shipment according to the order. These products are sorted out by electromagnetic random access memory, which can push the transportation chute to the switch rail.
From the read-write head that collects data to the random access memory that issues commands, the distance is only 20 cm, and time is limited. therefore,RFIDThe system faces the following precise requirements: it takes up to 350 milliseconds to complete the picking command from reading data from the code carrier. Turck used a programmable Profibus gateway and a CoDeSys program specially written for Leineweber to complete this solution. Once the read-write head records a code carrier, the program automatically writes the UID of the code carrier in the Profibus gateway data output register. In this way, the PLC does not need to issue a read command in advance, just simply read the Profibus register. Only in this way can products be picked out via Profibus and SQL database within 350 milliseconds.
Challenge from EMC
Obviously, in this particular application, there is another challenge that must be overcome: the countless plastic packaging used to protect the trousers rubs against each other during transportation to generate static electricity, which causes the read-write head of the initial link to malfunction. “Each read-write head performs about 500,000 read operations per week. It is difficult to determine what is the cause of one of the read errors.” Bernd Hettig explained, “Here, we really appreciate Turck. The company’s great help and ubiquitous support. Instead of leaving the customer aside when the product is sold out, they sent someone to help us analyze and solve the problem.” Now, the read/write head is replaced by a metal one, and the reading is wrong. It never happened again.
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