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Mould change system helps to reduce machine downtime

Mould change system helps to reduce machine downtime

An innovative change system for injection moulds has led to significantly reduced set-up times for an automotive supplier.

Increasing variety and smaller batch sizes very much determine production in the automotive industry today. What this means for suppliers can be seen by taking a look at the Faurecia plant for plastic parts. Here, 40 ton injection moulds have to be changed several times per shift - an operation that can be accomplished safely and economically, thanks to an integrated solution from Staubli.

Faurecia belongs to the French group, PSA Peugeot Citroen, and was formed in 1999 from the two companies, Bertrand Faure and Ecia, a Peugeot alliance. Today, the group, which has 94,000 employees at 320 locations, ranks sixth in the world's largest automotive suppliers. In the German plant in Sinntal-Sterbfritz, plastic parts for the vehicle exterior are manufactured. These include complete front-end modules, bumpers, sills and various design elements for the premium segment. For the high-quality plastic parts to be finished, sprayed in the vehicle colour and delivered just-in-time to the conveyor belts of the OEM, a three-shift operation is in place in their Rhön factory.

The production is characterised by small batches. A standard batch in the production of raw parts today comprises only 250 to 300 pieces. The two main reasons for these smaller batches are a rapidly increasing variety and the logistically demanding just-in-time delivery. This means multiple tool changes per shift on the four large injection moulding machines in the Faurecia production - a difficult task when one considers that the dies can weigh up to 40 tons.

"Valuable time was often lost during the transfer of the dies," comments Halil Havan, UAP manager in the injection moulding department at Faurecia. "That's why the job for our system partners was to create a new solution adapted to the current situation in order to reduce our down-time."

The new, innovative mould change system from St_ubli was brought seamlessly into operation at the beginning of 2012 without interrupting production. Since then the integrated system solution has taken over the transfer of the dies on a rail trolley. In addition, the controls of the change system also manage the intelligent tool storage. Fully automated workflows, the shortest routes and reduced machine downtime are the results.

The high-tech steel moulds are moved from the 70m long tool storage facility, fully automatically, into the injection molding machine on a rail tool shuttle from Stäubli. In one journey, the trolley can deliver the tool, and at the same time, remove the previous tool. During the change, both dies are briefly on board together. Then the trolley, which has an impressive load capacity of 110 tons moves into the correct position, to the millimetre, from which it pushes the tool into the injection molding machine using a chain-driven push-pull mechanism. The numerous quick and multi-couplings for media circuits and electrical energy are still coupled manually with the machine in this application by two experienced employees. But the sophisticated Stäubli technology reduces this part to just a few minutes. Further elements of the tool change, such as centering and clamping, occur automatically using the powerful Stäubli clamping cylinder.

Stäubli project manager Stefan Patsch, who has supported the project from the planning phase through to implementation, says: "There are many advanced individual systems which dovetail closely within this system solution, and without which such integrated management of the complex processes would not be possible." These include the optical scanning systems for millimetre precise detection of the positions for tool and trolley, as well as the sophisticated push-pull system, which makes the precise tool positioning so safe, quick and simple.

A further key element of the system is the integration of optimised warehouse logistics. Havan highlights what this means: "The control of the tool change system permanently corresponds to the production planning. Once it is decided which of the 37 stored tools is required next, the trolley puts the tool in the exact position in the storage which is the shortest distance from the injection molding machine in question. Thus, the tool is waiting in 'pole position' with the shortest route to the mould, ready to be used, which allowed us to reduce the set-up times even further."

Through the permanent optimisation of storage allocation, with the continuous goal of having the shortest transport distance, the Stäubli trolley is in operation almost around the clock - either for predictive optimisation runs within the storage facility or for tool change on the injection mould machines.

Stäubli is a longstanding partner of Faurecia in Sterbfritz, for the robot gripper change system for removal of components, for tool transport and clamping technology, as well as for the complete media and power supply for the tools. "Stäubli has more than 50 years experience in the area of quick mould change - a solid foundation for customer-specific solutions with maximum process reliability," says Karl-Heinz Griesbeck, QMC divisional manager at Stäubli.
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