Mondelez is a major international player in the food industry, with many well-known brands such as Côte d'Or, Milka, and Oreo in its portfolio. Both the cookie and chocolate divisions of the company have a factory in Herentals. The cookie factory is where LU cookies are made, among other treats. Mondelez Chocolates produces Leo cookies, Côte d'Or bars and Easter eggs.
The new Ergomix project supports 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 original aim of improving ergonomics for operators. In the past, eggs were mixed by manually picking from bowls with different flavors, which was very labor-intensive. This is now done fully automatically in the new machine.
Positioning of funnels above the conveyor belt
As soon as the eggs leave the forming line and are individually packaged, they are transported on a conveyor belt to the new machine below, where they are first placed in large pallet crates according to flavor. These bowls are then prepared for mixing by a robot or are picked up by a mobile robot for temporary storage in a warehouse. Once all the flavors required to make a mixture are ready, the eggs are transported via funnels to specific positions on a wide conveyor belt so that all the flavors are lined up next to one another on this conveyor belt. At the end, the eggs are returned to a pallet container, where they are perfectly mixed at this moment.
An initial challenge facing the drive technology was that the eggs have to be distributed neatly when the pallet containers are filled, otherwise they would not be level, which would make it impossible to stack the containers. The second challenge was to position the funnels above the conveyor belt from which the mixture is picked, which had to be a flexible system because not every mixture contains the same number of different flavors. Finally, a suitable drive had to be found for the robot's gripper, which has to move the pallet containers weighing 150 kg.
Fewer design constraints
"Our starting point for this project was not to use pneumatics," says Bob Aerts from the technical department at Mondelez. "The thinking was that electric drives perform 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 initial situation and the applications we wanted to build, but were also able to offer all the components we needed to implement it."
The demand for electric drives is certainly nothing new for Festo. "We see this segment growing by more than 20% per year," says Johan De Pauw, sales engineer at Festo. "Certain applications are difficult or impossible to realize with compressed air due to the speeds or the required flexibility in positioning. With electric drives, there are far fewer restrictions in terms of design and production. In addition, the total cost of ownership in this application is lower with electric drives than with pneumatic ones."
Betecem was responsible for planning the machine, with Koen Roobaert, application engineer at Festo, consulting on the selection of components. Alax Automation was called in for the programming. "The collaboration went very smoothly," says Bob Aerts. "One of Festo's advantages was that all components were provided with links to all documents and files that could be used in engineering and dimensioning tools right from the quotation stage. This meant that everyone had the right information to get started right away.
Electric cylinders
In order to fill the pallet spaces evenly, a system was developed in which the conveyor belt that feeds the eggs can be moved to the left and right via two toothed belt shafts with a servo motor and torsion shaft. The conveyor belt can also be extended forwards and backwards using an electric cylinder with a spindle in the extension of the conveyor belt. In this way, the system can position itself so that it can place the eggs anywhere on the pallet. The controller receives feedback from the load cells under the container and the flow rate of the feed so that it can determine exactly where there is still space in the container.
The positioning of the funnels above the wide belt for mixing was also realized with electric axes. This allows the positions to be automatically adjusted to the number of flavors that will be combined in a particular mixture. The entire machine no longer needs to be operated manually. The machine is located in the basement in an air-conditioned room, and operates fully automatically. The robot's gripper, which moves the pallet boxes, was also equipped with an ESBF electric cylinder with servo motor. All CMMT servo motor controllers are located in a control cabinet outside the air-conditioned room. These communicate via Profinet with the PLC that controls the system.
Switching over with software
The new system has now been in operation for some time, and the electric drives have already proven their worth. In the process of filling the pallet boxes evenly, for example, it took a long time to find the right parameters to achieve an optimum result. The advantage of electric drives is that the speeds and positions can easily be adjusted using the software. Changing the line on which the mixtures are produced is also done entirely via the software.
"Another advantage of Festo was that they offer a complete range of components," says Bob Aerts. "This includes not only the mechanical drives, gear units, motors and actuators, but also all the necessary mechanical fittings and accessories. This has helped us enormously with standardization, and also ensures that all components are perfectly coordinated. We would not have been able to achieve the flexibility that we now have with this machine with pneumatic drives."