B&R powered - Premium-grade PET recycling

PET plastic bottles are the most common form of beverage packaging. The versatile thermoplastic is perfectly suited for bottle-to-bottle recycling but can also be used to make film for food packaging. This is the specialty of Starlinger visotec, who develops high-end machines for just this purpose. The entire control solution for these machines comes from B&R. After all, premium machines call for premium automation.

 Family-owned Starlinger is based in Austria and leads the world market in the area of machinery and processing technology for woven plastic bags. In 2000, Starlinger introduced a new division dedicated to the development of technology and machine solutions for efficient recycling of various plastic materials including PE, PP, PA, PS and PET. Engineers at viscotec developed a solid state polycondensation (SSP) reactor that decontaminates raw material to produce high-purity rPET plastic.

"The main feature of our solution is that we're able to guarantee the dwell time of every particle in the process. That clearly sets our system apart from many others," explains Christoph Niederhuber, area sales manager for Latin America. "Our process does not involve mixing the material. That allows us to achieve exceptionally high levels of purification efficiency, even with extremely contaminated raw material. Often, the results considerably surpass even the most stringent limit values imposed by international directives. That's why we like to use the term super clean." In 2007, the Starlinger viscotec SSP reactor was ready for series production. Since then, the company has supplied nearly eighty viscoSTAR and deCON reactors.

Food-grade film from 100% recycled PET

The new fully automated viscoSHEET production line from Starlinger viscotec converts 100% recycled PET into food-grade packaging film.

Today, Starlinger viscotec has grown to 40 employees.

The opening of the company's new production site this past year was accompanied by a live demonstration of an innovative new product: the new viscoSHEET film production line, which turns shredded PET "bottle flakes" into food-grade packaging film in thicknesses ranging from 0.3 to 1 mm. "The film it produces can continue on directly to further processing steps, where it is formed into packaging products such as egg cartons or containers for fresh fruit," says Christoph Niederhuber, naming but two of the countless applications for the new machine. "PET recycling, though nothing new in Europe, is just starting to take off in places like South America and Asia – so there's a great deal of potential out there for the viscoSHEET."

With its modular construction, the viscoSHEET is divided into decontamination, dosing, extrusion, calendar, quality inspection and automatic winder units. "Each line we produce is fully assembled right here and undergoes extensive testing," says Christian Lauber, head of electronics and automation at Starlinger viscotec. "It is then deconstructed into its constituent segments – each designed specifically for the dimensions of a freight container – and sent on its way to the customer." This modular philosophy is incorporated into the machine's design all the way down to its automation components. "The control and drive technology is also exceptionally modular and distributed across multiple control cabinets. Our ultimate goal is that, when customers are setting up the machine on-site, there is only a single power supply line and a single bus cable to be connected for each cabinet."

The automation technology in detail

The solid partnership between B&R and Starlinger is built on many years of successful cooperation. B&R control technology is the factory standard at all Starlinger locations worldwide – and is therefore found in every viscotec system – together with ACOPOS drives and HMI technology from B&R. The single-source automation solution is rounded off by integrated safety technology and across-the-board communication via the powerful real-time Ethernet POWERLINK bus – including the openSAFETY protocol for transmitting safety-relevant data. The control and HMI applications are designed in the Automation Studio engineering system. "When it comes to software, all Starlinger departments use a consistent standard and a shared library," explains Lauber. "As a result, it was perfectly natural to take the automatic winder developed by our textile devision and integrate it in the viscoSHEET solution." In total, the solution involves around sixty X20 controllers with 220 X20 I/O slices, including both standard and safety modules, as well as thirty ACOPOS drives.

An absolute first in the industry: B&R 8LT torque motors easily handle the high inertia of the water-cooled rollers in the viscotec calendar unit while also ensuring highly precise synchronization.

The fully-integrated real-time POWERLINK bus system and the independent and safety-oriented openSAFETY protocol fulfill all of Starlinger viscotec's requirements for a decentralized and modular system design.

Motion control with no compromises

With B&R's comprehensive range of drive technology, Starlinger viscotec did not have to make any compromises when selecting components to meet its motion control requirements. The confined space available in the extruder's dosing unit still provides plenty of room for B&R's compact servo technology, including the exceptionally low-inertia 8LV synchronous motors and the ACOPOSmicro servo drive. These rugged devices easily withstand the heat given off by the extruder. The extruder itself is driven by a combination of 315 kW AC motors and ACOPOSinverter P84 VFDs. After leaving the extruder, the liquid PET melt is fed into Starlinger viscotec's specially developed calendar unit that passes the material over rollers, where it cools and solidifies into a film. The calendar's three water-cooled rollers are driven by 8LT torque motors with a nominal torque of 225 Nm and a peak torque of up to 816 Nm, with the modular ACOPOSmulti system providing closed loop control of the process.

Christian Lauber- Head of Electronics and Automation at Starlinger visotec "Working with B&R was a pleasure, and – as always – they came through at every step of the way." "

A solution that simply works

"The water cooling makes the rollers relatively heavy, so there is a lot of inertia to deal with. At the same time, the drives need to be very precisely synchronized since this step in the process plays a decisive role in the quality of the final product," emphasizes Lauber. "We've equipped this line with the world's first calendar driven by torque motors – a real innovation. We decided against the traditional solution with an induction motor, inverter and belt drive. The torque motors are virtually maintenance-free, and the torque monitor, torque limiter and speed control functions provided by the B&R solution are outstanding." The same ACOPOSmulti drives that control the torque motors also control the motors of the hoist, gap adjuster and positioning unit. As the film passes through the quality inspection unit, it is measured and scanned by cameras before being wound and trimmed by the winding unit. ACOPOSinverter P74 VFDs control the induction motors for both of these modules' cylinder drives. "B&R's VFDs are so technologically sophisticated that we were able to use much more inexpensive induction motors in place of the servo drives that would normally be required," explains Lauber.

 ACOPOSmulti drives provide highly precise synchronization for the torque motors – with high-performance communication via the real-time Ethernet POWERLINK bus.

A remote X20 control station combines standard and safety I/O slices.

Christoph Niederhuber- Area Sales Manager for the Latin American Market at Starlinger viscotec "Our SSP reactor allows us to achieve exceptionally high levels of purification efficiency, even with extremely contaminated raw material. Often, the results considerably surpass even the most stringent limit values imposed by international directives."

A partnership that fits

A powerful industrial PC – B&R's Automation PC 810 – serves as the central platform for all of the line's software, interfaces with all of its distributed controllers and also runs the HMI application. The line's operating unit is an Automation Panel 920 with touch screen display. "Due to the complexity of this system, we really put B&R's engineers to the test at every level of support, especially when it came to motion control," recalls Lauber. "Working with B&R was a pleasure, and – as always – they came through at every step of the way. A project of this scope and depth can only succeed when you have a partner you can trust – a partner who brings their own innovative ideas and engineering know-how to the table."