Mondelez is a large, international player in the food industry, with many renowned brands in its portfolio, such as Côte d'Or, Milka and Oreo. In Herentals, both the company's cookie and chocolate divisions have a factory. The cookie factory is where Lu's cookies, among others, are produced. At Mondelez Chocolates, Leo cookies, Côte d'Or bars and Easter eggs are made.
The new Ergomix project is supporting the production of Easter eggs - a production that runs practically all year round in order to have enough stock at Easter to meet the sudden demand for this seasonal product. The name of the project refers to its initial objective of improving ergonomics for the operators. In the past, eggs were mixed by manually putting together trays of different flavours, which was labour intensive. In the new facility, this is done fully automatically.
Positioning hoppers above conveyor belt
Once the eggs come off the forming line and are individually packed, they go via conveyor belt to the new plant below where they are initially put into large pallet bins by flavour. Those trays are then prepared via a robot 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 certain positions on a wide conveyor in such a way that on that conveyor all the flavours are lined up next to each other. At the end, the eggs re-enter a pallet bin where they are perfectly mixed at that moment.
A first challenge in terms of drive technology was to ensure that the eggs are neatly distributed when filling the pallet bins, because otherwise they would not be level which would make stacking the bins impossible. The second challenge was positioning the hoppers over the conveyor on which the mix is assembled, which had to be a flexible system because not every mix contains the same number of different flavours. Finally, a suitable drive also had to be found for the gripper on the robot, which has to move the 150kg pallet bins.
Fewer constraints in design
"Our starting point for this project was not to use pneumatics," says 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 this to Festo and they not only understood our starting point and the applications we wanted to build, but were also able to offer all the components needed to make it all happen."
For Festo, the demand for electric drives is certainly not new. "We see that segment increasing by more than 20% per year," says Johan De Pauw, Sales Engineer at Festo. "Certain applications are difficult or not at all achievable with compressed air because of the speeds or the need for flexibility in positioning. With electric drives, there are a lot 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 installation was in the hands of Betecem, with Koen Roobaert, Application Engineer at Festo, advising on the component selection. Alax Automation was called upon for the programming. "That cooperation went very smoothly," says Bob Aerts. "An advantage with Festo was that from the quotation onwards, links were provided with all components to all documents and files that could be used in tools for engineering and dimensioning. As a result, everyone had the right information from the start to get started right away.
Electric cylinders
To fill the pallet bins evenly, a system was designed in which the conveyor belt feeding the eggs can be moved left and right via two timing belt shafts with a servo motor and torsion shaft. With an electric cylinder with spindle in the extension of the conveyor belt, it can also be extended forwards and backwards. In this way, 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. Thereby, the positions can be automatically adjusted to the number of flavours to be brought together in a given mix. Now the entire installation no longer requires any manual handling. The installation is located in the basement in a conditioned room and operates fully automatically. Also, the gripper on the robot that moves the pallet boxes was equipped with an ESBF electric cylinder with servo motor. In the electrical cabinet just outside the conditioned room are all the CMMT servo motor controllers. These communicate via Profinet with the PLC that controls the installation.
Switching from the software
The new installation has been operational for some time now and the advantages of the electric drives have already proven themselves. With the process to fill the pallet boxes evenly, for example, it 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.
"Another advantage with Festo was that they offer a full range of components," says Bob Aerts. "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."