Software-based product manipulation on the fly
In highly dynamic packaging solutions, fractions of a second determine profitability. That is why the Swedish 3Button Group is replacing rigid mechanics with software-defined motion control – based on the XTS from Beckhoff. This has turned a new stacking and packaging system into a compact high-speed system that inspects sensitive in-mold labeling products at high throughput, handles them precisely, and keeps them available around the clock.
The hardest currency for fast-moving consumer goods, which are produced in runs of millions, is high overall equipment effectiveness (OEE). The 3Button Group, which has established itself as a system integrator in the plastics, food, and pharmaceutical sectors, meets the high demands of end users: Not only do machines need to run quickly and reliably, they also need to be so intuitive to operate that it takes no time at all to put them into operation. “Our customers run their packaging lines non-stop,” explains Johan Enander, head of R&D and Sustainability at the 3Button Group. “As soon as a machine stops, the cost clock starts ticking.” This is why the Swedish system integrator relies on an operating concept that only requires 3 buttons: start, stop, and reset. Behind this, however, lies sophisticated technology – because keeping operation as simple as possible requires all the more machine intelligence in the background. This is impressively demonstrated by a solution for inspecting, stacking, and packaging coffee cup lids.
Speed and geometry
The real challenge in handling plastic lids of this kind lies in the combination of high speed and sensitive material. This applies in particular to in-mold labeling (IML), where a pre-printed label is inserted directly into the mold before the liquid plastic is injected. An IML lid is light and sensitive, and must not be damaged on the visible surfaces. In conventional systems, these requirements tend to clash: mechanical conveyor belts are often used to achieve throughput of around 100 million units per year, but they offer little flexibility and can lead to product damage, jams, and breakdowns in high-speed operation.
“Speed and precision come together in the packaging phase,” says Johan Enander, analyzing the situation. “If the throughput is very high and products have an unusual shape, using conventional conveyor technology is a costly, laborious process.” A conventional system would require a large number of servo drives, pneumatic cylinders, sensors, and complex mechanics to separate, align, and stack the lids. This would not only have massively increased the space required by the system, but would also have resulted in it needing more maintenance – a risk that was unacceptable given the required level of availability of over 99%. “A conventional conveyor system would have been too complex and costly,” summarizes Enander. “That’s why the solution for us was to abandon rigid mechanics in favor of a software-based approach.”
A paradigm shift in material flow
The heart of the newly developed system, the XTS from Beckhoff, is a track on which 14 independent movers move. In contrast to chain conveyors, where the product is transported passively and is tied to the cycle of the chain, the movers act as active, servo-electrically controlled units. Each mover can be individually accelerated, braked, and positioned. A powerful Ultra-compact Industrial PC C6032 acts as the central control unit, combining not only the logic (PLC), but also motion control and image processing in one runtime environment. The positions of the movers are updated via EtherCAT communication with a cycle time in the microsecond range. “This enables synchronization between the movers and the external process stations, something that would be unattainable with purely mechanical solutions,” emphasizes Enander. “With XTS, we control each product individually and position it at high speed exactly where we need it.” In practice, this means that the lids are taken from the injection molding machine, gripped individually by the movers, and dynamically guided past the various stations. As the movers move independently of each other, it is possible to compensate for process fluctuations to an excellent standard. If a lid needs to be inspected for longer, only this one mover slows down, while subsequent units catch up – the buffer is already integrated in the transport system.
Integrated inline image processing
Quality control is a critical aspect of IML products. The label must fit perfectly and must not have any bubbles or scratches. At this point, the 3Button Group benefits from the seamless integration of vision systems into the Beckhoff automation platform. As TwinCAT 3 controls both the movement of the XTS movers and image processing, no complex synchronization is required. The system knows the mover’s position in the sub-millimeter range at all times. The camera is triggered exactly when the lid is in optimum focus – during movement. This eliminates dead times that would occur with stop-and-go operation. Defective products are immediately identified and ejected as rejects without interrupting the continuous material flow.
Another advantage of the PC-based control architecture is the option to perform simulations. Even before the first mechanical part of the system was manufactured, the 3Button Group was able to simulate the behavior of the XTS movers and their interaction with the robots in the system. This is because TwinCAT 3 enables the control code to be tested in a virtual environment. As a result, collision tests, cycle time calculations, and motion sequences optimizations were carried out as early on as the engineering phase. For the end customer, this meant that commissioning time on site was dramatically reduced. Any bottlenecks in the material flow had already been identified and eliminated in the simulation. The software architecture also enables fast format changes. If a different lid is to be produced in the future, the mechanics do not need to be modified. All that is needed is a parameter update in the software to adapt the movers’ motion profiles to the new product geometry.
Increased OEE, increased economic efficiency
Technological finesse is meaningless if it is not profitable. But this is precisely where the Swedish integrator’s solution demonstrates its strengths. The absence of complex mechanics significantly reduces maintenance costs. The XTS works almost wear-free, as the movers are held magnetically and do not require any sliding contacts or cable chains. At the same time, the compact design of the XTS reduces the footprint of the system. The movers run on a closed track, meaning that outward and return paths can be used for transportation. This is a compelling argument in production halls where space is at a premium. However, throughput remains the decisive factor. “If you save just a few tenths of a second per cycle in 24/7 operation, the increase in production is significant in the long term,” confirms Johan Enander.
The 100 percent inspection and gentle handling minimize rejects and prevent complaints. Accordingly, the system not only delivers quantity, but also assured quality. For the customer, the focus of the investment shifts away from initial machine costs toward the total cost of ownership (TCO) instead. For the 3Button Group, the decision in favor of Beckhoff was also a strategic choice against proprietary black box systems. Ultimately, the openness of PC-based control makes it possible to integrate different technologies and standards – whether that means a connection to higher-level MES/ERP systems via OPC UA or integrating third-party components. “We really appreciate the openness and integration,” confirms Enander. “It allows us to focus on offering our customers added value, instead of having to deal with technological limitations.”
A partnership for the future
The successful implementation of the IML packaging system is another step forward in the collaboration with Beckhoff, which started in 2019. With around ten XTS applications delivered, the integrator already has a lot of experience in this area and is planning to deliver more machines this year. “In future, we also want to combine XTS and XTS Ecoline motor modules in order to adapt machines precisely to customers’ needs,” explains Enander. This will make it possible to implement cost-optimized hybrid solutions that use high-performance segments in cases where process speed is critical, and deploy Ecoline modules on the transport routes in between. As a result, the 3Button Group will have a foundation that not only meets the increasing demands for speed and precision, but also offers the flexibility to respond quickly to future market trends.
