Linear Transport System Syncs 120 Axes for Ultra-Fast Capping
A new cap applicator from Tetra Pak uses the Beckhoff XTS linear servo transport system to deliver 25,000 precisely sealed cartons per hour, tripling output over conventional portion-package cappers that run at 9,000/hour, while combining digital control with flexible, high-speed motion.
At its Modena, Italy, development center, Tetra Pak engineers recently designed a next-generation capping machine that applies plastic caps to beverage cartons at what they say is unprecedented speed and precision. The new Tetra Pak Cap Applicator 40 Speed Hyper uses a linear servo transport system, the XTS from Beckhoff, that precisely synchronizes over 120 motion axes, doubling system reliability and enabling quick changeovers across packaging formats. The system has been so successful that Tetra Pak’s pilot end-user customer (who could not be named), impressed by its reliability, performance, and flexibility, has described it as a “magic machine.”
He adds that the requirements placed on the new machine were demanding, both because of the high processing rate and the complex 3D geometry of the cap, which must meet extremely high quality standards when applying adhesive.
To meet these goals, Tetra Pak’s engineering team says that it selected Beckhoff PC-based control to provide the necessary computing power and flexibility.
“Our customers are increasingly demanding systems with a high degree of digitalization and connectivity,” adds Paolo Scarabelli, director of innovation, analytics & line solutions at Tetra Pak. “The PC-based control technology from Beckhoff forms the ideal basis for this. XTS also makes it easy to replace work that used to be mechanical with software functions, representing an additional step towards a digitalized machine. With the Tetra Pak Cap Applicator 40 Speed Hyper, for example, we were able to shift the boundary between digital and mechanical machine components in favor of digitalization. In our specific case, this means that we have full digital control of more machine functions and can operate the system more reliably.”
If the vision system detects adhesive deviation, the software automatically switches cam plates for the coupled mover pairs during operation, restoring the precise path.
“We also use asset health monitoring to check the state of our equipment,” Bassissi adds. “All of this is crucial to quality assurance and, as such, to the success of the product. Ultimately, beverage containers can only be sent to end customers if they are reliably sealed and completely leak-tight.”
The Tetra Pak Cap Applicator 40 Speed Hyper’s motion architecture presents a real challenge: more than 120 real axes and 10 virtual master axes. Two parallel 4.5-m linear tracks each carry 55 movers, and roughly 10 rotary servo axes manage packaging transfer and hot melt application.
Because of the cap’s 3D shape, X, Y, and Z motions must synchronize with the movers’ trajectories. Each pair of movers is mechanically linked but operates across two parallel transport systems.
“It does not matter whether the movers are on one system arranged in a row or on two different systems,” says Stefano Flore, director of packaging lines and embedded automation at Tetra Pak. “The control software takes advantage of this – it always moves the movers in complete synchronization with each other.”
Flore notes that the linear transport system offers exceptional flexibility thanks to its modular design.
“The ability to change the track length and the number of movers means that hardly any work is involved in creating machine variants with a higher or lower product throughput,” he says. “It is also very easy to change over to different packaging formats to accommodate other fill quantities and pack tops or caps with different shapes, for example.”
New configurations are handled entirely in software by adjusting mover spacing and motion parameters.
“After the caps have been picked up by the corresponding brackets on the movers, up to six synchronized movers form a batch to apply the adhesive profile," Flore continues. "For this purpose, the cap bracket moves on the X-axis and Y-axis by means of a mechanical coupling with the associated mover of the parallel system. At this point, the system compensates for any tolerances, such as those caused by the adhesive nozzle. The cap is then applied to the carton packaging with precision and monitored by means of image processing. The system also assists with error-free gluing by maintaining the correct contact pressure using a precisely defined level of transverse force.”
Adhesive is applied to the plastic caps in the upper XTS area, and the plastic caps are then glued to the cartons with high precision in the lower area – in a process that’s almost invisible to the naked eye at full speed.
The contact pressure that Flore mentions above results from the coordinated interaction of the two coupled gantry movers. The high degree of digital control also allows data from the motion system to feed directly into diagnostics. Deviations from parameters can be quickly localized or even prevented.
Tetra Pak also chose to use control technology from Beckhoff because all system-related components are available from a single source, which the company says guarantees seamless, efficient integration. At the heart of the machine control system are two C6032 ultra-compact Industrial PCs that handle the HMI applications, the two XTS systems, and motion control via TwinCAT NC PTP and TwinCAT PLC. In addition, a wide range of functions can be combined in a single control unit, including machine simulation. The selected PC-based hardware platform also offers plenty of potential to add new functionality in the future.
“TwinCAT exploits the full potential of PC-based control. This ranges from a wide variety of programming languages, including object-oriented languages, to integration in Microsoft Visual Studio and comprehensive network configuration options, to excellent multi-core processor support," Scarabelli says. "In addition, the software is well structured, and its open nature makes it possible to not only use the extensive function libraries, but also seamlessly integrate your own libraries to create machine-specific condition monitoring. We also make extensive use of TwinCAT Scope for development-related analyses. Overall, TwinCAT gives us the best possible support, including when it comes to achieving our goal of standardized software development.”
Flore adds that the openness of the platform plays a key role.
“The platform is backed by powerful and open EtherCAT communication, which seamlessly integrates the I/O system, functional safety, and drive technology. The Beckhoff AX8000 servo drives offer clear advantages due to the very high dynamics and precise control of the motion sequences. In addition, the modular design is extremely compact and flexible, allowing the simple addition of more axes if required. This is supported by the wide range of AM8000 servomotors and its fine scaling in terms of motor type, power, winding type, and other aspects.”
Davide Borghi, manager of advanced analytics for equipment at Tetra Pak, adds that the whole exercise of launching new equipment on a new software and components platform relies on good service and support.
“Support is particularly important when changing the machine concept. For the Tetra Pak Cap Applicator 40 Speed Hyper, this came into play right from the point when feasibility testing was performed, and was especially useful for configuring the system and its huge range of functions. Support was provided flawlessly in all cases – on-site in Italy and from experts in Germany, and right up to each of the different management levels involved.”
Looking ahead, Tetra Pak expects to build on this success.
“We believe that No Cable Technology (NCT) is a promising further development,” says Flore. “And we are already testing the possibilities that XPlanar can bring to a number of applications. We also see attractive advantages of the MX-System for control cabinet-free automation and of TwinCAT Runtime for Linux. So there is a great deal of potential to surprise our end users–like the pilot customer in this case–by giving them another ‘magic machine.’”
Looking for engineering services? Our curated list features 100+ companies specializing in civil, process, structural, and electrical engineering. Many also offer construction, design, and architecture services. Download to access company names, markets served, key services, contact information, and more!
Two XTS linear transport systems installed parallel to each other enable extremely fast and highly precise joining of the plastic cap and carton packaging – supported by additional motion axes implemented using AM8000 servomotors (top).© Beckhoff
Adhesive is applied to the plastic caps in the upper XTS area, and the plastic caps are then glued to the cartons with high precision in the lower area – in a process that’s almost invisible to the naked eye at full speed.© Beckhoff
