New technology enables new solutions. At the K trade fair in Düsseldorf, Starlinger recently presented a machine that demonstrated this twice over. On the one hand, the machine produces woven polypropylene sacks with innovative new punched handles for easy carrying, and on the other it features cutting-edge technology from Sick and B&R. Like the new handles, the benefits IO-Link brings to the solution will certainly carry weight with customers.
For certain products, packaging makes all the difference. Not only does it protect the contents during transport and grab attention from the store shelf, it can also help the consumer carry it home. Quite often, plastics like polypropylene play a key role. Processed into strips and woven into fabric, it offers strength and durability that go far beyond the conventional plastic shopping bag. It's hard to imagine carrying home tile adhesive or cement mix by the shovel full. Instead, these products are sold in sacks, which must be extremely robust to handle up to 20 or 25 kilograms of material. For the producers of these materials, choosing the right sack is crucial.
When a conversation turns to the topic of woven plastic packaging, it won't be long before the name Starlinger is mentioned. Headquartered in Weissenbach, Austria, the company has a 45-year history developing and building machines that make robust and versatile polypropylene sacks – around 15 billion of them per year, as a matter of fact. From processing the primary material to weaving and printing the fabric and all the way to the finished sack itself – Starlinger has the entire production process covered. Over the years, the renowned machine builder has proven a knack for introducing innovations that are well received on the global market.
With its internationally patented Ad*Star block bottom valve sacks, Starlinger has significantly reduced the occurrence of breakage – a clear advantage for cement mix producers and their customers. Capable of holding up to 50 kilograms, Ad*Star sacks are ideal for all types of dry bulk goods for wholesale and retail, from construction materials and chemicals to feedstuff. Starlinger's latest innovation was unveiled at the K trade fair for plastics and rubber in Düsseldorf: a new machine that makes block bottom valve sacks with a convenient handle.
"These sacks have never been available with a handle before. The new design has the handle welded firmly right on the sack. This makes the heavy loads much more manageable," says Rene Weiss, head of electrical engineering at Starlinger. In the EU, block bottom bags carry up to 25 kilograms, while elsewhere in the world up to 50 kilograms are permitted.
Production of an Ad*Star block bottom valve sack begins with polypropylene pellets, which are melted and extruded into a film that is then cut into tapes six to eight millimeters wide. The tapes are drawn out and heat-treated to improve durability. Having once again been wound onto reels, the tape is then mounted on a creel, woven into a polypropylene tube and respooled onto another reel – all at breathtaking speed. This tube can be further processed. In the case of the Ad*Star, a heated polypropylene film about 15 to 25 micrometers thick is applied. Then the material is spooled up again.
Printing – industrial printing or OPP lamination – is also performed as a reel-to-reel process, which Starlinger has continuously developed and fine-tuned over many years. In the conversion line, the sacks are cut, folded and the handle is welded on. Production of the handles also runs – you guessed it – reel to reel. "To make the handles, the primary material – woven polypropylene tape – is fed straight from the reel into the machine. There it is folded into four layers and punched to form the shape of the handle. Then the material is unfolded and spooled onto the final production reel with a precisely defined tension," explains Weiss. From there, the roll goes to the next machine, where the handles are welded onto the sacks. This step is completed with hot air and pressure alone and doesn't require any additional materials.
Once the handles have been punched, spooling them onto the final reel is a particularly sensitive step. Too much or too little tension would shift the positioning and result in a warped handle. This is a challenge both for the high-precision torque control of the actuator and the sensor system that detects the reel diameter. "Absolute precision is essential here," says Weiss. "Even the smallest deviation can easily cause big problems." This is a job for Sick sensor systems. An encased DT35-B15251 laser distance sensor detects the position of the reel shaft and thus the diameter of the completed handle reel. The distance between where the sensor is installed and the reel shaft makes it possible to calculate the reel diameter with a high level of precision.
In developing the new line, Starlinger truly thought of everything: commissioning, ongoing maintenance, future adaptations and interfaces with upstream and downstream equipment were all important topics. "Our motto is to plan for all contingencies, because looking ahead helps avoid unnecessary costs later on," says Weiss. "That's why we wanted an Industry 4.0 type sensor here – one that can do more than just measure. The vision of Industry 4.0 is for sensors to provide the master and higher-level databases not just with measurements, but also the sensor's serial number, diagnostic data and other important information. Equally important are easy configuration and the ability to network with other machines. With the combination of IO-Link and POWERLINK, that's no problem at all – and many of the things we would have wished for ten or fifteen years ago are finally possible. The DT 35 laser distance sensor connected via IO-Link was the perfect solution."
Because the distance sensor on the handle converter is not readily accessible, remote configuration was particularly important. "The sensor's specifications only need to be entered into the control system once," says electrical engineer Michael Hecher. "That way, all the processes match up right from the start, and no other settings are required." Even in the event of a sensor replacement, all the essential data is retained and there is no need to recalibrate. "Not having to go find a parameter list or use additional software to configure the sensor is a huge benefit. In the future, it will also be possible to read a component's serial number to identify whether it's the original that came with the machine. If there is an error, you'll immediately see which part is affected. Optical sensors will also be able to report the degree of contamination so the operator knows when they need to be cleaned," says Hecher.
IO-Link offers numerous design benefits. There is no need for shielded cables, tedious analog cabling is eliminated entirely, and the system is fieldbus independent. The end user has the advantage of being able to replace the sensors without having to give it much thought. "Until now, the customer has had to maintain a spare parts inventory of uniform sensor types, and there would often be problems because certain applications require very specific programming," explains Hecher. "If the new sensor wasn't adjusted correctly, the customer would have to fall back on complicated calibration mechanisms or had to be trained by us in order to correctly install the replacement. Thanks to IO-Link, that's now a thing of the past."
In addition to the IO-Link sensor, another highlight of the Starlinger machine is the X20 control system from B&R. The X20DS438A I/O module functions as the IO-Link master. Process data is passed on to other nodes via the open POWERLINK interface. This was particularly important to Starlinger, because the company has eliminated proprietary bus systems from its portfolio entirely. Each machine is now equipped with as many as 45 POWERLINK nodes. "In addition to simplicity and stability, switching to POWERLINK brought us two distinct advantages. One was safety integration, and the other was the system's decentralized architecture. B&R's POWERLINK nodes allow for connections to solutions from various manufacturers – including not only actuators, but in the future cameras and sensors as well. This kind of seamless connectivity is one of the cornerstones of Industry 4.0," says Weiss. The numerous advantages of open POWERLINK interfaces are why Starlinger, B&R and Sick are working to advance the technology as members of the Ethernet POWERLINK Standardization Group (EPSG).
From the central control system, remote POWERLINK nodes can be added via a bus controller. Also connected via the bus controller is the IO-Link master, from which the IO-Link layer is accessed radially. "Hierarchically speaking, process and safety control are handled on the POWERLINK layer, and the sensor technology at the IO-Link layer. That applies to the entire production process," explains Weiss. "All the actuating elements, including both servo drives and inverters, are controlled via the POWERLINK fieldbus layer using information received via IO-Link. This enables our customers to have their entire production firmly under control and makes them flexible enough to be prepared for future developments," Weiss is clearly pleased to report.
Head of Electrical Engineering, Starlinger
"Hierarchically speaking, process and safety control are handled on the POWERLINK layer, and the sensor technology at the IO-Link layer. All the actuating elements, including both servo drives and inverters, are controlled via the POWERLINK fieldbus layer using information received via IO-Link. This enables our customers to have their entire production firmly under control and makes them flexible enough to be prepared for future developments."