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Electric trumps pneumatics on chocolate egg packaging line

22 March 2024

Mondelez has chosen electric drive technology instead of pneumatics for a new automated chocolate Easter egg mixing installation because it offered lower energy consumption, higher safety and more flexibility in controlling speeds and positions.

The egg mixing line uses a system of conveyors to ensure that a good mix of flavours is found in every pack of chocolate eggs. 

Designated the Ergomix project, it was instigated to support the production of Easter eggs, with the objective of improving ergonomics for operators. Traditionally the finished eggs would be mixed manually, by putting together trays of different flavours – a labour-intensive process. In the new facility, this process has been fully automated.

The perfect mix
Once the eggs come off the forming line and are individually packed, they go via conveyor belt to the new plant where they are sorted into large pallet bins by flavour. These trays are then prepared via a robot either for mixing or to be picked up by a mobile robot for temporary storage in a warehouse. Once all the necessary flavours for making a mix are ready, the eggs are transported via funnels to precise positions on a wide conveyor so that all the flavours are lined up next to each other. At the end, the eggs re-enter a pallet bin where the different flavours are brought together.

One challenge was to ensure that the eggs are neatly distributed when filling the pallet bins, otherwise they would not be level, which would make stacking the bins impossible. Another challenge was positioning the hoppers over the conveyor on which the mix is assembled. This required a flexible system because not every mix contains the same number of different flavours. Finally, a suitable solution also had to be found for the gripper on the robot, which has to move the 150kg pallet bins.

"Our starting point for this project was not to use pneumatics," explained Bob Aerts of the Engineering Department at Mondelez. "The reasoning was that electric drives score better in terms of energy consumption, and it is also easier to implement all aspects of machine safety. We presented all of this information to Festo and it was able to offer all the components needed to make it all happen."

A move away from pneumatic to electric was not a surprise to Festo. "We see this segment increasing by more than 20% per year," said Johan De Pauw, Sales Engineer at Festo. "Certain applications are difficult or not at all achievable with compressed air because of the speeds involved or the need for flexibility in positioning. With electric drives, there are fewer limitations in how you can design and manufacture. Moreover, the total cost of ownership in this application is lower with electric than with pneumatic drives."

The design of the new plant was undertaken by Belgian machine builder, Betecem, with Festo advising on the component selection. Alax Automation was responsible for the programming. "It went very smoothly," said Bob. "From the quotation onwards, links were provided with all components to all the documents and files that could be used in tools for engineering and dimensioning. As a result, everyone had the right information from the outset to get started right away."

Precise positioning
The new Ergomix installation is located in the basement in an air-conditioned room and operates fully automatically. To fill the pallet bins evenly, the system has been designed so that the conveyor belt feeding the eggs can be moved left and right via two timing belt shafts equipped with a servo motor and torsion shaft. An electric cylinder with spindle in the extension of the conveyor belt means it can also be extended forwards and backwards. This combination means the system can position itself to drop eggs at any position in the pallet bin. The controller receives feedback from the weighing cells under the bin and the flow rate of the supply so that it can determine exactly where in the bin there is still room.

The positioning of the hoppers above the wide belt for mixing was also realised with electric axes. They allow the positions to be automatically adjusted to the number of flavours which need to be brought together in a given mix. 

Also, the gripper on the robot that moves the pallet boxes was equipped with a Festo electric cylinder with servo motor. All the servo motor controllers are housed in the electrical cabinet just outside the air-conditioned room. These communicate via Profinet with the PLC that controls the installation. Combining different egg flavours therefore no longer requires any manual handling.

Operational advantages
The new installation is already fully operational, and the electric drives have already proven themselves. The process of filling the pallet boxes evenly took some searching for the right parameters to obtain an optimal result. The advantage of electric drives is that it is easy to play with speeds and positions from the software. Changing the line on which the mixes are made is also done entirely from the software. 

"An advantage with Festo was that it can offer a full range of components," concluded Bob. "That includes not only the mechanical drives, gearboxes, motors and drives but also all the necessary mechanical fittings and accessories. This has helped enormously in standardising and also ensures that all the components are perfectly matched. The flexibility we now have with this installation, we would not have been able to achieve with pneumatic drives."


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