igusThe demand for packaged beverages is increasing. To ensure that the different sized glass and PET bottles are handled quickly and reliably, so-called clamping stars play an important role in the complex beverage bottling lines at Krones AG. They are exposed to very high loads, especially in the upper power range. Ever since they started using the two-component plastic rollers Igus GmbH have been equipped, their service life has almost doubled.

"Brewhouse, filtration, bottling, logistics - we not only realize complete breweries, but are also at home in the beverage industry worldwide," says Jürgen Steimmer, group manager for labeling technology, container fittings and special stars of Krones AG, Neutraubling, supplier of beverage filling and packaging technology. "The demand for complete solutions is increasing. We serve the entire value chain of our customers, from beverage production to distribution of goods. "igus1

Krones plans, develops and manufactures machines and complete systems for the areas of process, filling and packaging technology as well as intralogistics. Millions of bottles, cans and mold containers are "processed" daily with Krones equipment; especially in breweries, the soft drink industry as well as in wine, sparkling wine and spirits manufacturers, but also in the food and beverage industry as well as the chemical, pharmaceutical and cosmetic industries. Krones has developed far beyond traditional machine and plant construction since it was founded 1951. The company has become the "all-round partner" for its customers. Mechanical engineering, plant know-how, process engineering, microbiology and information technology were harmoniously combined and optimized.

Water in front of soft drinks and beer

In 2008, people around the world drank around 208 billion liters of packaged water. With a share of 23,4%, water has replaced carbonated soft drinks as the most popular drink. Soft drinks accounted for around 203 billion liters, which corresponds to a share of 22,8% of the total volume. With just under 184 billion liters, beer follows (20,6%) and is thus clearly ahead of milk (14,3%).

Around 40% of the global beverage volume is packaged in PET containers, and the trend is rising. This puts PET well ahead of packaging materials made of glass, into which around a quarter of all drinks went. The domains of PET packaging are water and soft drinks, while alcoholic beverages are preferred in glass. The proportion of beverages that are packaged in cans is around 12%. Beer, soft drinks and niche segments such as energy drinks are often bottled in cans. A total of around 10,5% of the world's bottled beverage volume flows into cardboard packaging.

Clamping stars for bottle inspection

igus2Krones is a global player in this environment. "Our machines and systems offer customers added value worldwide," says Steimmer. "We strive to find the right solution for every requirement." Example: Inspection, filling and labeling technology of glass and PET bottles. Here, so-called terminal stars prove their efficiency. Their field of application is above all the inspection technology. On a carousel, the bottles are passed by cameras at breakneck speed. These not only check the condition and type of the individual bottle, but also detect whether there are still soiling such as straws or cigarette butts in it. Subsequently, the bottles are passed through a terminal star to other areas, such as the labeling.

Such clamping stars are available in four different star pitch circle diameters. You are e.g. B. interesting in systems for large breweries or mineral water bottlers who have to handle many different bottle sizes. Since a clamping star compensates for a diameter tolerance of 20 mm, it does not only grip a certain bottle size. It does not have to be changed, which saves the filling companies changeover times and costs. “The stars are permanently in use in the machines. But their service life used to be limited, ”says Steimmer looking back. "That's why we urgently had to remedy this."

That's exactly what Krones implemented together with igus. The Neutraublinger have been working together with the Cologne polymer storage specialists for almost 20 years. In the filling and packaging machines the most diverse plastic bearings are installed, all tribologically optimized. The lubrication-free and maintenance-free plastic bushings are convincing in the food environment (hygienic design) and are usually designed to meet customer-specific requirements.igus3

Inside special plastic, outside TPU

Krones and igus have jointly developed a solution for the terminal star to significantly extend its service life. In addition, two-component rollers have now been used in the spring clips for around two years. The polymer material "iglidur J" was chosen for the internal bearing, which has proven itself for years in all industrial areas of packaging and filling technology. The outer material consists of a TPU jacket. This new two-component variant has proven to be the ideal solution for the requirements on site. It minimizes wear and tear and ensures even longer machine running times.

Depending on the diameter, a clamping star can consist of 4, 8, 12, 18 and 24 parts. Between the staple packages, a PEEK axis of rotation passes through, which - controlled by a control pin - ensures the opening and closing of the clamp. "In the past, the rolls used to be worn too quickly, so customers often had to overhaul the clamp star," says Steimmer. Their bottling plants stood still, the number of complaints increased. Often the customers had then put a second star in stock to replace it quickly in an emergency. Of course that was associated with additional costs that they did not want to take on. "There was an urgent need for action here. We have now removed this weak point together with igus. "

Highly loaded in breweries

The clamping star is heavily loaded by breweries in everyday operations. In the upper performance range in large breweries up to 66.000 bottles per hour are passed through, which means it comes hourly to 66.000 opening and closing processes. In order to increase the life of the rollers, therefore, numerous experiments were carried out with a variety of materials. "We first contacted various plastic suppliers," says Steimmer. "But the results were not satisfactory. Either the rollers wear even more or the rotation axis. Only when we got igus on board, we gradually came closer to solving the problem. "Bernhard Hofstetter, the responsible technical sales consultant at igus, explains:" Up to that point, we at Krones were known as a specialist for plastic bearings, but not as a roll specialist. This application was a great opportunity to bring other areas of our portfolio into focus as well. "

New variant of polymer bearing and roller

igus5After extensive tests, including in the company's own technical center in Cologne, Krones was presented with a variant made of a polymer bearing and roller. First tests with rollers made of "iglidur J" material initially showed that the difference in the coefficient of friction from the inside to the outside was not large enough to ensure permanent wear-free movements on the expensive PEEK rotary axis. Only the new two-component variant with a good coefficient of friction inside and a poor coefficient of friction outside led to the result. The "iglidur J" bottom bracket with TPU outer jacket now turns easily and, above all, wear-free on the axle and ensures smooth operation. "We now have no more complaints," confirms Steimmer, "the service life has been significantly extended."

Tribologically optimized

The two-component bearing was tested for almost a year before it was installed in the first Krones systems. While orange was initially chosen for the TPU outer jacket, it is now supplied in the company's blue color. "We were able to kill two birds with one stone here," said Steimmer. "Firstly, blue goes better with our machines and secondly, the blue color has RoHS approval, which is why these rollers have been installed since summer 2009." The tribo-optimized plastic rollers are supplied in 6 different sizes. This has something to do with the size of the bottles and thus the opening angle of the clamps. The rollers are available for bottle diameters from 50 to 110 mm. "The opening angle for a 3-liter Coke bottle, for example, which is common on the American market, must be correspondingly large for effective handling," explains Steimmer. Due to the size and weight of the bottles, "only" 20.000 bottles per hour can be channeled over the multifunction star in these filling systems.

Not only customer requirements, but also standards and approvals are constantly changing. Suppliers must respond to this. Tobias Vogel, Head of Sales, igus: "We have been supplying special solutions for the machines and systems of Krones for many years." There is a constant need to modify the wear and tear, durability and service life. For example, with its maintenance-free spindle linear systems, the company has solved many requirements in the past. Krones beverage filling and packaging machines today contain numerous customer-specific parts. Originated from the igus catalog program, which includes 29 standard materials, these are still in use - sometimes in modified form.

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