Mondelez is a major international player in the food industry that has many well-known brands such as Côte d'Or, Milka and Oreo in its portfolio. Both the biscuit and chocolate divisions of the business have a factory in Herentals. The biscuit factory is where Lu's biscuits are made, among other treats. Mondelez Chocolates produces Leo biscuits, Côte d'Or bars and Easter eggs.
The new Ergomix project supports the production of Easter eggs,a production process that runs practically all year round so that there is 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, the eggs were mixed by manually combining bowls with different flavours, which was a very labour-intensive process. This is now done fully automatically in the new system.
Positioning funnels above the conveyor belt
As soon as the eggs leave the moulding line and are individually packaged, they are transported on a conveyor belt to the new system below, where they are sorted into pallet crates according to flavour. These bowls are then prepared for mixing by a robot or picked up by a mobile robot for temporary storage in a warehouse. As soon as all the flavours needed to produce a mix are ready, the eggs are transported to specific positions on a wide conveyor belt using funnels so that all the flavours are lined up next to each other. At the end, the eggs are returned to a pallet container, where they are perfectly mixed.
An initial challenge for the drive technology was that the eggs had to be filled and distributed evenly into the pallet containers, otherwise they would not be level and that would make stacking them impossible. The second challenge was positioning the funnels above the conveyor belt on which the mix is assembled. This had to be a flexible system as not every mix contains the same number of different flavours. Finally, a suitable drive had to be found for the robot gripper, which has to move the 150 kg pallet containers.
Fewer design constraints
"Our initial thinking for this project was not to use pneumatics," says Bob Aerts from the technical department at Mondelez. "The idea was that electric drives perform better in terms of energy consumption, and it is also easier to implement all aspects of machinery safety. We presented this to Festo, and they not only understood our initial thoughts and the applications for which we wanted to build a system, but were also able to offer all the components that we needed to make it happen."
For Festo, the demand for electric drives is certainly not new. "We see this segment grow by more than 20% per year," says Johan De Pauw, Sales Engineer at Festo. "Certain applications are difficult or even impossible to implement using compressed air because of the speeds or the flexibility needed for positioning. With electric drives, there are far fewer restrictions in terms of design and production. In addition, the total cost of ownership for this application is lower with electric drives than with pneumatic ones."
Betecem was responsible for planning the system, with Koen Roobaert, Application Engineer at Festo, advising on the choice of components. Alax Automation was called in for the programming. "The collaboration went very smoothly," says Bob Aerts. "One of the advantages of Festo was that, right from the offer phase, all components were provided with links to all the documentation and files that could be used for engineering and sizing. 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 by two toothed belt shafts with a servo motor and torsion shaft. The conveyor belt can also be moved backwards and forwards using an electric cylinder with a ball screw in the extension area of the conveyor belt. This enables the system to 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 funnels above the wide belt for mixing are also positioned using electric axes. This allows the positions to be automatically adjusted to the number of flavours that have to be combined in a particular mix. There is no longer a need for the system to be operated manually. The system is located in an air-conditioned room in the basement and operates fully automatically. The robot gripper, which moves the pallet boxes, was also equipped with an electric cylinder ESBF with a servo motor. All servo motor controllers CMMT are located in a control cabinet outside the air-conditioned room. These communicate with the PLC that controls the system via PROFINET.
Change in software
The new system has now been in use for some time and the electric drives have already proved their worth. It took a long time, for example, to find the right parameters and achieve the optimum result for filling the pallet boxes evenly. The advantage of electric drives is that you can easily adjust the speeds and positions via the software. Changing the line on which the mixes are produced is also done entirely by 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 process valves and accessories. This has helped us enormously with standardisation and also ensures that all components are perfectly matched. We would not have been able to achieve the flexibility that we now have with this system using pneumatic drives."