Almost everyone has heard of the games and puzzles produced in Ravensburg, known all over the world under the trade mark "Ravensburger" and extremely popular with young and old. Endurance is necessary to assemble a jigsaw puzzle and fantasy in order to escape from tricky situations in a game and finish as the winner.

But this is only part of the story. Before the fun can start, the puzzles and games have to be developed, produced and shipped all over the world with creativity, know-how and special equipment. In this respect, the "Ravensburger Spieleverlag GmbH" in Ravensburg is just like any other production factory. In both cases, the final steps in the production process are the packing of the individual products (games and puzzles) and the palletising and wrapping of these to form larger storage and shipping units. In order to make the packing and storage, particularly of puzzles, as rational as possible, the responsible persons at Ravensburger decided to invest in a new, automated packing and palletising system capable of handling about 10,000 puzzles per hour.

The reasons for this massive investment in an automated packing line, between final assembly and the high-lift warehouse, are manifold. They result from the increasing demands for better delivery quality and greater quantities, the desire to make better use of pallets and the high-lift warehouse by formation of optimal product layers on the pallets, and the need to considerably reduce, or do away with, the thousands of trips by fork-lift trucks which, until then, had been necessary for the internal transport and material flow after the production process. At the beginning of the planning phase, the possibility of thoroughly modernising the existing layer-palletising system, which was installed in 1989, was considered, but this idea was soon dropped in favour of a completely new system.

After a careful and extensive selection process, the robot and material-flow specialists FPT Robotik GmbH & Co., Schattbucher Straße 10 in D-88279 Amtzell, were awarded the contract to plan and deliver the complete system for automatic packing and palletising of the entire puzzle production at Ravensburger.

Messrs. FPT won the contract in the face of very stiff competition. The decisive factors were the convincing overall concept and the lucrative approach to the solution, which was competitive without costing more. In the past, FPT had already implemented several very important automation projects at Ravensburger. The closeness to Ravensburger - Amtzell is only a few kilometres away from the Ravensburger head office - makes cooperation easier, since no time is wasted on long journeys, and  also means that FPT can, in the case of a problem, be at the Ravensburger factory within 20 minutes.
The specification called for a direct connection from the production lines to the high-lift warehouse by means of a fully automatic, unmanned material flow from the packing stations into the warehouse. Above all, this automation was to eliminate the 90,000 fork-lift truck movements which were previously necessary in and around the warehouse.

The solution was to take into account the fact that the puzzles are packed in boxes of about 80 different sizes, resulting in 80 different layer patterns on the pallets, that suitably flexible handling and gripper systems would be necessary and that these should be capable of handling the output of four production lines. Each box containing a puzzle or game weighs between 100 grams and 12 kg, and each line produces between 30 and 45 boxes per minute, depending on the box size. In order to handle the output of the production lines and the many different product sizes, powerful grippers are necessary which can grip between one and 40 boxes at a time and can lift loads weighing up to (4 x 12 kg =) 48 kg. Since the production facilities run in three shifts in a six-day week during a period of 4 to 5 months each year and in two shifts in a six-day week in the other months, the planned packing and palletising system - including the handling and material-flow systems - had to meet extremely high requirements with respect to performance and availability. It should also be mentioned that the puzzles leaving the production line are enclosed in perforated, porous plastic film and that this film may under no circumstances be damaged or deformed. Since, however, the film is initially still warm and "sticky" and later becomes smooth and slippery as it cools, particular attention had to be paid to the selection of a suitable gripper system.

As experienced general contractors, FPT Robotik consulted the specialists for vacuum systems and components, J. Schmalz GmbH in D-72293 Glatten, for support in the area of handling and gripping film-packs, boxes and empty pallets. In such applications, the gripper systems are of prime importance, since they form the only interface between the products and the robots. The palletising system planned and delivered by FPT Robotik consists, amongst other things, of four pre-stackers in the form of linear stacking units and equipped with large-area vacuum grippers of the type FM from Schmalz. It also has four "5-axis industrial robots" from Kuka, each capable of lifting 180 kg and equipped with a combined mechanical/vacuum gripper for gripping the film-packed puzzles and stacking them precisely on the waiting pallets. Last but not least, there is a further 6-axis robot from Kuka, equipped with a large-area vacuum gripper of the type SBX, which places the empty Euro or industry pallets in position. This gripper has a further, separate vacuum gripper system which is used to handle the sheets of cardboard which are placed between the product layers.

The pre-stackers
The four pre-stackers are linear handling systems, each equipped with 2 x 3 = 6 FM large-area vacuum gripper modules. These gripper, mounted in two parallel rows, can lift the film-packed puzzles coming from the production lines and stack them on a conveyor belt in so-called "tower rows". The vacuum for the large-area vacuum gripper system is generated electrically by a compact vacuum pump of the type EVE-TR 40AC3. This ensures that the vacuum needed for the very short gripping and handling cycles is built up very quickly and is permanently available. The stacks of boxes pass via a second conveyor belt to the industrial robot (palletising robot) with its special, combined gripper.

The palletising robot
The gripper system of each palletising robot consists of seven large-area vacuum gripper modules FM with the dimensions 400 x 120 mm, equipped with flow resistors. These special grippers can execute three different gripping actions. Both mechanical and vacuum gripping is used for the "pincer" action, while only vacuum is used for the action "diagonal" (two-sided gripping) and for the action "flat gripping". In the latter case, the outer gripper module is swung out by 90°, so that the products are gripped only from top.
An optimum layer pattern is very important, particularly in the case of the last - and thus only partially filled pallet - at the end of a run or when the product changes. The gripper must be able to distribute the remaining products optimally on the pallet and must therefore be very flexible. This is why the various gripping actions are so important!
Another important factor is that the puzzles must be positioned precisely on the pallet, since non-uniform stacking would result in damage to the lower layers. Only pallets which have been loaded cleanly can be stored in a high-lift warehouse without problems and without impairing the product quality.

In the special combi-grippers of the palletising robots, not only the large-area vacuum gripper modules are supplied by Schmalz - the electric vacuum pump EVE-TR 80AC3, the components for control of the vacuum (vacuum switches and valves) and the vacuum filters also come from the Schmalz product range.

The pallet stacker
The pallet stacker is based on a robot equipped with a large-area vacuum gripper of the type SBX, with an integrated multi-stage ejector SEM which is characterised by its enormous suction capacity. This stacker is responsible for sorting and positioning the empty Euro pallets and industrial pallets. The pallets are carefully examined for damage and are measured precisely. A sheet of paper is also laid between the pallets, using a separate gripper. This is equipped with four bellows-type suction pads made of Vulkollan, with 1.5 corrugations and a diameter of 40 mm, and a vacuum ejector of the type SCP to generate the vacuum.
This station prepares about 120 pallets per hour. The stacks of pallets are then moved by a so-called "traversing trolley" to the individual palletising stations, arriving there "just in time".
The full pallets are picked up by the traversing trolley and moved to a film-lacking station, where they are wrapped in plastic film, hooped (if necessary) and suitable labelled. They then pass via a roller conveyor directly to the high-lift warehouse.

In order to ensure problem-free execution of the material-flow processes, the robot systems and the grippers in all stations must run continuously and reliably. This is why FPT relied, in this case as in the past 10 years, on the cooperation with and the product and service quality supplied by Schmalz. It should also be mentioned that all of the vacuum gripper systems were assembled from complete systems and vacuum components from Schmalz. This made the design, purchasing and assembly far easier and also much cheaper, since no specially designed parts were needed.

Hint: all pictures are also available in high quality, on request.