The tyre retreading process at Continental's new lifecycle plant requires close collaboration between production and logistics. To manage workflows on the factory floor and warehouse, the tyre maker has therefore opted to interface the warehouse and production management systems together.
Reducing emissions of the CO2 greenhouse gas and careful management of our resources are important topics of our time. Continental is stepping up to this challenge with what is to date its unique hot- plus cold-process approach to re-treading HGV tyres, whereby significantly less energy is consumed than when manufacturing new tyres. Customers such as trucking companies can thereby benefit from significantly lower prices. The operational basis for the business is the new ContiLifeCycle Plant, which the international tyre maker and automotive parts supplier opened in November 2013 at its Stöcken site near Hannover, Germany.
Wanted: an integrated solution for warehouse and production...
The tyre retreading process requires close collaboration between production and logistics. Accordingly, the company decided to deploy an integrated software solution for the management of its warehouse and manufacturing processes. The invitation to tender for the new system was based on a requirements specification developed by Continental. "At this early stage, a number of processes couldn't be defined right down to the last detail, however," says Jochen Hebe from Continental Tyres, Information Technology Competence Centre Manufacturing.
Accordingly, Continental was looking for a full-service partner who was able to offer an end-to-end solution that could cover the vast majority of requirements from manufacturing and warehousing right out-of-the-box. In addition, a comprehensive approach to tackling the project was required, since Continental was also looking to achieve deep integration of the application into its Group-wide SAP-driven Enterprise Resource Planning (ERP) environment. The final selection round was won by SAP integration specialists IGZ GmbH from Falkenberg in northern Bavaria. "Our decision was based on a scoring matrix," Hebe explains. "Scoring criteria included performance, flexibility, and full-service development/implementation, for example – all of which was offered by our partner." IGZ's concept was also sound: the software solution pitched is based on SAP Manufacturing Execution (SAP ME) for discrete manufacturing, plus SAP Extended Warehouse Management (SAP EWM) for handling logistics functionality such as warehousing and transportation. As a Manufacturing Execution System (MES), SAP ME (Manufacturing Execution) adds the necessary functionality to the ERP software. "In this way, production planning is extended by making integrated production control and handling available to the shop-floor," says IGZ executive director Johann Zrenner. SAP EWM (SAP Extended Warehouse Management) supplements this with a functional platform for production logistics, so as to achieve tight integration between the works of the logistics and production units.
Dynamic production control with radio frequency
As Zrenner explains, the successful conclusion of the project by his software and consulting company has put into production the world's first consortium project integrating the two system modules in the form of an all-in-one solution. Today, the production management module is already notified of the tyre casing deliveries automatically beforehand. Accordingly, this stock is therefore directly visible in the manufacturing software as a work list via the "Production Operator Dashboard". "Once the newly generated barcode is affixed to the tyre in Goods Receipt, it then has a new identity," explains Lingling Luo, Head of Finance & Controlling at Conti's Stöcken plant. The tyre casings are first given a visual inspection and are then processed by the "shearograph", which checks them for potential damage with a pressure test. The results are entered and documented in the MES solution. The casings are then sorted and racked before being handed over to the interim warehouse using the radio frequency (RF) putaway screen. "The handover to the buffer storage area simultaneously forms the interface between ME and EWM," continues Lingling Luo. The subsequent steps within production, and the triggering of replenishment from the production or interim warehouse directly to the requesting work centres in production, are in turn handled by the production management system. Here, the corresponding stock removal and transportation to the production work centre are performed automatically in the warehouse management suite by a SAP EWM (SAP Extended Warehouse Management) radio frequency transaction.
From the buffing station to vulcanisation
In the first production step, the tyre casings staged from the warehouse pass through the buffing station, where the tyre's tread and sidewall strip are rasped off. Continental has integrated a procedure into this process whereby the rasped off material is collected and reprocessed in a neighbouring recycling plant. Here, all of the production machinery is supplied with data from the Manufacturing Execution software via a standardised OPC UA interface. Repairs are then made to the "raw" casing. This is where the third stage of the sorting process occurs: In a procedure again guided by the MES, casings suitable for reprocessing are then forwarded through to either cold-process or hot-process retreading. The software controls the procedure here, depending on the data collected in the first stage. With cold-process retreading, a pre-moulded and pre-vulcanised tread is applied to the tyre casing. Once so prepared, the tyre is then packed in a curing bag and passed through to a pressure vessel. With this process complete, the retreaded tyre is ready for final inspection – including a pressure test – at the test bed. In hot-process retreading, the new material for the tread and sidewall strip is applied directly from the extruder to the buffed tyre casing. The chosen mixture is automatically logged by the software and validated against formulations stored in the system. The process interlocking thereby achieved is absolutely essential for tyre reprocessing. With the material applied, the casing or "green tyre" is then passed to the kiln plant (curing press), where it is reheated and vulcanised under pressure with the chosen tread pattern. This also renews the sidewalls, meaning that Continental's 18 presses actually remould the entire tyre. The result is given an initial visual inspection before then being sent for a pressure test.
From kick-off to wrap-up in a matter of months
Putaway for the retreaded tyres in the finished goods warehouse is also initiated by the production management system. A sorting screen is used for handover to the warehouse module and movement into the finished goods warehouse. Currently, the plant in Hannover reprocesses around 300 tyres a day. When working at full capacity, the new production plant should be able to handle a daily workload of around 700 tyres. Compared to the 18 curing presses now in use, some 28 presses and 20 production work centres will then be available for tyre retreading. Workplaces for personnel are also managed and controlled via the MES module. "The time frame for bringing the plant online was fairly narrow. And the implementation of SAP ME/EWM (SAP Manufacturing Execution/SAP Extended Warehouse Management) was also very ambitious in every respect," comments Hebe. Yet the Manufacturing Manager is now very pleased with the result that has been achieved: Just six months were needed to get from the initial specification to the start of production at the plant, following the successful go-live of the first "Production Cycle" project phase. Phase 2 – "Machine Interfacing" – was successfully completed only a little later in March 2014. Continental is also planning to draw on the know-how of the software and consulting company in the future: the partners have signed a three-year agreement and will thus be addressing and implementing additional optimisation work together. For Lingling Luo, reporting is an especially important topic in this context. At the same time, Continental is already considering rolling out subsequent SAP ME/EWM projects to its tyre reprocessing facilities in Mexico and Malaysia.
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