Turck30419The Kirschenhofer Maschinen GmbH developed for Britax Romans a system for production control and quality assurance in the production of child seats. Both companies have realized this without SPS and indeed over RFID-Tags and TBEN-S Ethernet multi-protocol modules from Turck in conjunction with Labview.

Anyone who has ever had to fit a child seat in a car appreciates the blessing of the Isofix standard. Click-clack and the seat is securely fixed in any car that has Isofix holder. The idea: The seat has two fixed anchors, through which it is latched into the Isofix grommets of the vehicle. We owe this alleviation to a collaboration between the child seat manufacturer Britax Römer Kindersicherheit GmbH and VW, who jointly raised the standard from the baptism. Meanwhile, it has become an international requirement for cars and child seats.

Turck10419The safety of child safety products is a matter of great concern to both customers and manufacturers. Production errors are not acceptable here and must be excluded as far as possible. However, manufacturers often do not even have it in their own hands, especially when suppliers supply faulty components. Therefore, the second goal is a faster, smoother product recall.

Slim system based on Labview

Britax Römer sought advice from the automation and special machinery manufacturer Kirschenhofer Maschinen GmbH before setting up its production line for the child seat "Advansafix IV". Those responsible on both sides quickly had a similar picture of how the largely manual production of the new child seat family could be automated. The system was to be controlled on the basis of Labview, a widely used system development software for test, measurement and control applications, and to use RFID data carriers as a database. The advantage: Britax Römer saves large production conversions and infrastructure investments.

Turck20419The production process of the Advansafix IV consists of 16 single steps. For each of these steps, there is a feature that can be checked. This begins with the construction of the seat base, the so-called base, and ends with the packaging of the seat in a carton. Each successful production step should be individually documented as "OK" (IO). If a station is omitted or can not be completed successfully, this feature remains marked as "Not OK" (NIO).

Tracking system without PLC and database

Nico Dreher, Process Engineer at Britax Römer and Project Manager, wanted a system that could also be used on the move to help identify seats at dealerships. Kirschenhofer developed a completely new system approach that could fulfill both requirements: process control with an RFID system that stores all data on the data medium on the product.


Igus plain bearings on tourSmall maintenance-free plain bearings made of plastic travel around the world


This sounds unspectacular at first, but has not yet been realized for a production tracking system in this form. Usually, tracking systems only use the ID of the data carrier and save the associated production data in a database to which all relevant process sites have access. But Kirschenhofer wanted to spare his customer exactly this server infrastructure - after all, every dealer should also have access to the database. A decentralized system without permanent database connection and without PLC has its advantages: mobility and independence as well as the costs. A small limitation lies in the limited storage capacity of the data carriers. You have to limit yourself to the relevant information and features.

Five central process steps as a proof of concept

Turck50419Once the rough sketch was in place, the five key positions of the 16-stage production were to be implemented in a pilot system as a "proof of concept". At the first station, the data carrier is glued into the base plate of what will later be the seat. An RFID read/write head checks that it is seated correctly by reading the freshly attached tag and writing it with the process image. A robot test cell was selected as the second station, in which the largely finished seat is visually checked for the 16 production features.

If seat variants are to be mapped at a later date, the test robot could select an alternative test procedure with different characteristics via the data carrier on the seat. The third station checks the Isofix function. Before the finished seat is packed, the fourth station checks whether all previous process steps have been documented as IO on the data carrier. The fifth station is the reworking station, where seats marked as NOK are reworked.


Kettcar for adultsKettcar for adults creates a range of up to 200 km


The entire process is mapped on the RFID data carrier. There is only one permitted sequence of production steps. The system ensures the correct sequence by setting the corresponding feature to OK at each of the four stations after a successful assembly phase. After station 1 (pasting the tag), only station 2 can follow. At station 2, a check is carried out to determine whether station 1 was carried out successfully at the present seat. Only then does the process continue.

Sticky disk with 320 byte space

Kirschenhofer found the suitable medium for this at Turck. Since the day is glued directly into the seat, it must not be too big. In addition, it must be relatively cheap because it remains on the product. Turck was able to offer a data carrier that met all requirements with the smart label TW-L36-18-F-B320. The thumbnail-sized sticker with 320 byte even holds more than the minimum size of data memory ready and can thus also map extensions of the later system, if once also nominal measuring ranges are mapped or additional stations are added.

Slim Solution: Tablet replaces PLC

Turck40419For such tracking and testing systems actually no PLC is needed. The processes are not time-critical and could also be captured by classic office hardware. However, the interfaces are often the problem. RFID interfaces are usually designed for connection to industrial Ethernet networks and therefore can not easily communicate with the applications on PCs or mobile devices.

Craig Craill, managing partner and PLC programmer at Kirschenhofer, was looking for a solution that would enable the operation of an RFID system without a PLC. The focal point was the rework station. The operator sees all the necessary information on a tablet PC. It indicates which feature is faulty and presents the target state of assembly in the final system on a single image. This system is based on standard software, so that Britax can enter images and texts himself without re-integration costs. Kirschenhofer uses the rework station Labview. However, since the software had no connection to the RFID system, a solution had to be found.

Interface between Labview and Ethernet / IP

Turck70419For the system at Britax Römer, Kirschenhofer chose compact TBEN-S-RFID interfaces and, depending on the station, different read / write heads from Turck. The TBEN-S module can output the RFID data from the read / write heads pre-filtered via Profinet, Ethernet / IP or Modbus TCP to higher-level systems, usually to controllers. Craill decided to program a direct interface between Labview and Ethernet / IP in order to avoid the detour via a controller. He expects a positive development of the protocol: "Ethernet / IP has a lot of potential because it has the advantages of an industrial Ethernet network, but in contrast to Profinet, it is completely open and works without license fees."

The programmer also rates the potential of the interface between Ethernet / IP and Labview as high as the software is a quasi-industry standard for test benches. Craig Craill and his colleagues at Kirschenhofer spent several months digging through some 900 man pages, delved deep into the Ethernet / IP codes, and created a Labview device description file similar to a driver. The previous experience with the pilot system confirms the smooth functioning of the interface and thus opens up room for follow-up projects for Kirschenhofer.

Another advantage of the system is that Britax Römer itself can define other features that can be supplemented and checked on the data carrier. The system is so open that you can supplement it without any programming knowledge. In addition, the employees of the seat manufacturer can adapt to extended production processes, the production of a different seat variant or even another product.

Disk-based system saves PLC and money

Craig Craill is aiming for a price comparison between PLC solution and Windows tablet: "Thanks to the solution without PLC, we were able to save several thousand euros at the Rework Station. A simple Windows Surface Tablet replaces a PLC, the screen and an additional IPC for database management. "The test robot is still controlled by a PLC in the current configuration stage. Again, Craill can imagine working without SPS. "Currently it is not yet because of the safety signals. But I have already tested the safety module TBPN from Turck. This could also be a control of the test robot without PLC set up. "


TU Chemnitz head restraintLighter headrest with organic sheet for the child car seat


But not only on the cost side, the project is convincing. The processes, especially in reworking, are now more efficient and safer. "In the past, you had to manually write down what the defect was on the product after the test, or even test each feature on the rework station itself. Today we put the seat in the station and see on the display which feature is wrong. That's a big advantage because it's faster and safer than it used to be, "said Nico Dreher, convinced of the solution.

For the rework station Kirschenhofer chose the elongated read / write head TNLR-Q80L400 because there are no fixed anchor points for the seat and the read / write head has to cover a larger area. "With the long read-write head, the day is recorded reliably in all positions. This allows the station to be used on a mobile basis and to capture the seats in closed boxes, "says Craig Craill, explaining the choice of the 80 x 400 mm RFID reader.

Efficient product logistics up to the dealer

Turck60419In the end, the successfully refurbished seats end up like the others at the end-of-line station. Here it is finally checked whether all features are IO. Only then will the seat receive its approval label with a unique serial number. Then it is packed in a box so that the data carrier can be read through the cardboard without opening the box.

"We can implement a mobile rework station ourselves. All we need is another tablet, a reader, the switch and a Labview license. Then we would be operational and could go in the event of a fault to the dealers and check the seats. That would be much more feasible than before, "says Nico Dreher. So far, in such a case all seats had to be removed from the boxes at the dealer in order to identify them clearly. Each seat then had to be returned to its exact packaging.

Now it's time to roll out to other stations. Of the Turck components Craig Craill is not convinced only since this project. "Kirschenhofer has been using the TBEN-S for a long time. We were among the first to test the I / O modules and were among the first to use the RFID modules. The multi-protocol concept convinces us because it means that we only have to stock one module. We are also convinced by the variety of read / write heads and data carriers. Such a package can only be found at Turck. "

The author Ralf Moder is a sales specialist at Turck.

 

You might also be interested in...

Encoder: Incremental, absolute and communicative

Encoder: Incremental, absolute and communicative

Turck offers non-contact and conventional encoders in various designs. The encoders are incremental, absolute...
RFID and Barcodes | Industrial identification

RFID and Barcodes | Industrial identification

Efficient and transparent processes are essential in modern production. Possibilities for optimization offer here...
Ethernet switches | The data driver in the network

Ethernet switches | The data driver in the network

In a world that increasingly relies on connectivity, reliable and efficient...
LED signal light with and without IO-Link

LED signal light with and without IO-Link

Turck offers various LED signal lights from the Banner Engineering portfolio. Each LED signal light implements a...
Turck | Your global automation partner

Turck | Your global automation partner

What's new at the Turck Group? In April, the new national company in Sweden replaces the sales office....
Temperature sensor – humidity sensor – vibration sensor

Temperature sensor – humidity sensor – vibration sensor

Turck's extensive portfolio of temperature sensors also in combination with humidity measurement or vibration measurement...