Fette Compacting manufactures tablet presses for the pharmaceutical and consumer goods industries and has set up a fully automated production system for the smallest batch sizes with the help of gripping, clamping and palletizing systems from Schunk.

Whether headache tablets, glucose tablets, soft drinks, washing-up liquid tabs or detonators for airbags: Fette Compacting's tablet presses and capsule machines are known worldwide for their efficiency and productivity. The market and technology leader's top model produces up to 1.6 million individual tablets per hour. As part of a reorganization of its production processes, the Schwarzenbek-based company has analysed its highly varied range of workpieces, clustered them and assigned them to different machine sizes. Whereas previously five machines had to be loaded manually and retooled four to seven times a day, the process is now organized more efficiently. 1,800 different parts with an edge length of up to 200 millimetres were assigned to three Grob G350 five-axis universal machining centers with pallet changers. The annual output is 32,000 pieces in total. A flexible production system from Promot Automation links the machines together in such a way that all workpieces can be produced fully automatically in any sequence and batch size with maximum flexibility. Schunk gripping systems and clamping devices ensure reliable handling and efficient clamping of the workpieces.

The heart of the system is the Vero-S-NSA-plus flat palletizing system from Schunk. Workpieces and clamping fixtures are set up on clamping pallets, stored in the workpiece magazine and successively loaded onto the machining centers. Thanks to a patented rapid and clamping stroke, the clamping system achieves pull-in forces of up to 20,000 Newtons and holding forces of more than 100,000 Newtons. All functional parts such as the base body, clamping slide and clamping rings are made of hardened stainless steel and are corrosion-resistant. The modules are also completely sealed. A forced air flow cleans the flat surfaces and short cones during the automated changeover, thus ensuring chip-free flatness of the pallet. Insertion radii on the clamping module enable fast and reliable joining even if the pallet is offset in the middle or slightly inclined. This allows tolerances of the handling system to be optimally compensated. Centering rings then ensure accurate positioning. Clamping slides ensure positive, self-locking fixing with high repeat accuracy. After machining, a lifting pin raises the pallet by up to 0.5 millimetres for workpiece changeover and simplifies the changeover process. All process steps are monitored via a dynamic pressure monitoring system.

With the Vero-S-NSR robot coupling, clamping pallets can be handled reliably at Fette Compacting. The Schunk zero-point clamping system ensures a secure hold on the machine table with maximum repeat accuracy. (Photo: Schunk)

A Vero-S-NSR interface from Schunk attached to the side of the clamping pallet handles the coupling with the robot. The lightweight coupling was specially developed for pallet handling in confined spaces and enables loading extremely close to the machine table. As parts outside the force flow are made of aluminum, while parts in the force flow are made of hardened stainless steel, the coupling achieves an optimum ratio of rigidity, robustness and weight. The locking mechanism is positive-locking and self-locking. Opening, closing and pallet presence are monitored via inductive proximity switches so that the entire changing process can be monitored. For greater process stability, the robot coupling is sealed against chips and cooling lubricants and is equipped with a cleaning function as standard. Steel inlays at the contact points make the robot couplings wear-resistant.

Fette Compacting was able to integrate the system directly into the table; it worked perfectly right from the start. As all set-up processes now take place parallel to production outside the machines, the three fully automated five-axis centers can be used more efficiently than the five manually loaded machines previously. Thanks to the automation, customers will be able to order spare parts via the web store in future and receive them within 24 hours. Customized parts, such as filling curves, can now also be produced within a very short time. pb