How Toyota use Hi-Temp RFID tags to track car bodies
The Toyota plant in Derby produces the Avensis and Corolla models for the European market. Opened in 1992, the plant now employs 3,700 people and has a production capacity of some 220,000 vehicles per year.
Cross-Check Systems, the ‘Data Collection Technology’ specialists, have recently been awarded the contract to upgrade the plants Burnaston paint shop tracking system. They are well known to Toyota, having implemented a similar system at their production plant in France some two years ago.
Upgrade and update RFID tags
The brief from Toyota Manufacturing UK was two-fold, firstly to increase the data size available for storage on the RFID tags, and secondly, to replace their current tags with longer life cycles. Cross-Check’s solution was to both supply and install RFID tagging hardware and modify the existing control software within the PLC’s. In addition, they supplied all of the special high temperature RFID tags, incorporating the innovative Philips I-CODE technology, to complement the RFID hardware manufactured by Escort Memory Systems Inc. (EMS).
The current I-CODE tags can handle up to 48 bytes of data, although only 40 are currently being used by Toyota. Philips is, however, currently developing an upgraded tag, which will be able to store up to 112 bytes.
All of the hardware and systems installed by Cross-Check have been configured to allow Toyota to up-grade to the new generation of Philips I-CODE (SLi) tags when they become available from EMS.
The new RFID tags, based upon the Philips I-CODE technology, has been specially developed by EMS to withstand temperatures of 210oC. Philips guarantee that their RFID tags will survive a minimum of 100,000 write cycles – unlike the old tag that required replacement after just 5000 “writes” – a vast improvement in performance!
The new passive I-CODE based tag is completely battery free and derives its energy from radio waves being transmitted by the antenna. Cross-Check have installed a total of 39 EMS LRP820-04 long-range passive readers and 800 LRP250HT tags for use within the paint shop. The EMS readers have been strategically placed at crucial areas of the paint shop process.
The paint shop process begins as the body enters the paint shop area from the weld shop, whereupon it enters a cleaning bath followed by an electro-coat dip for the rust proofing process to be completed. The body is then married with a carrier known as a dolly, upon which the LRP250HT passive read/write RFID tags is secured – there are currently 730 dollies in operation.
The body specification is then written to the tag along with other variables required for the paint process. Data written to the tag at this point stays with the body right up to leaving the paintshop area on-route to the Final Assembly section of the plant.
The current speed of the line is one body every 62 seconds, although during tests at the plant, it was proven that one in 51 seconds could also be handled by the tags, should a production increase be required. At one point during the paint process, the body is lifted from the dolly and placed into an overhead carrier to enable access to the underside of the body to apply the underbody coating. To maintain the continuity of information, data from the dolly tag is transferred to the carrier tag, thus ensuring 100% integrity of data at all times.
Once the underbody process is complete, the body is returned to the dolly system. This operation is completed when the data from the carrier is transferred back to the dolly tag prior to entering the ovens for baking at 145 oC. The bodies then emerge ready for their primer paint coat, after which they enter another oven, this time at a temperature of 178 oC.
Data on the tags is used to route the bodies directly from the ovens through inspection ready for the topcoat spray booths. Data on the tags assists the operators as the colour and build specification is read from the tags at the very first station in the process. Once again, the dolly carries the body through the final paint oven, again at 178 oC. The body is then allowed to cool before it proceeds to final inspection where it is checked. Further routing information is then written to the tag, which directs the body along its specific path.
The final stage of the body’s journey is when it enters the bank known as PFDS. The completed painted bodies are then separated into Avensis and Corolla and are sequenced at this point ready for the next step of their journey to the Avensis and Corolla assembly shops. Once again, data stored on the tag helps the operator schedule in the body to the sequence of the production line, and to balance high and low specification models.
As the body and the dolly part company for the final time, the tag is completely erased of all its production data, ready to begin the paint shop cycle all over again with a new body from the weld shop.
Whereas most of the reading points throughout the process are dedicated to controlling, some stations provide ‘pure data’ for use by the management team at Toyota Manufacturing UK, to review and address any alterations to processing that may be required.
Mr. Paul Mason, Managing Director of Cross-Check Systems Limited commented,
“I feel our ‘Plan-Do-Evaluate’ methodology greatly assisted the smooth installation of this project.
“Our experience allowed us to assist with both the customised tag bracket design and the custom software requirements to the two LRP7400 hand held terminals, allowing much greater flexibility for the maintenance staff at Toyota”