Krones AG was founded in 1951 and is headquartered in Neutraubling, Bavaria, Germany. The company manufactures and sells machinery, plants and systems primarily for the beverage industry.
One step in the overall process during filling is the labelling of bottles. The company uses various methods including the stretch and shrink system unique to the ‘Sleevematic’ technology, where pieces of label are unwound from rolls, cut and then attached to the bottles.
For the filling process to run as fast as possible, an uninterrupted flow is required here. If a roll of labels is depleted, it needs to be replaced by a new one without stopping the entire plant. Here the so-called ‘buffer conveyor’ is used as a film storage, in which the company has incorporated the use of lubrication- and maintenance-free xiros plastic ball bearings from energy chain systems and polymer plain bearings provider Igus.
The film storage serves to prepare for roll change: depending on the size of the system, up to 36 guide rollers made of aluminium are used here to guide the webs of labels. One half of guide rollers is arranged offset next to each other in a row, which can move up and down on a rail. The other half is firmly installed above.
During operation, the rows of rollers move apart vertically; the band of labels is routed one after the other through the system by a lower and an upper guide roller respectively, thereby creating a ‘buffer’ for the ongoing operation.
Once a roll with labels is depleted, the moving row with guide rollers moves back to the stationary one, whereby the buffer becomes smaller. Thus the user will have enough time to switch to a new label roll. The plant does not remain uninfluenced by this though—this process would somewhat slow down operation speed still—but this technology ensures that operation remains uninterrupted.
Distinct Advantage: Smooth Running
“Imperative for us here is the smooth running of the ball bearings in the guide rollers,” explains Sören Meissner, designer at the department of inspection and labelling technology at Krones. “In the past we have used metallic bearings. However, this was not smooth enough, sometimes making the complete roll stop and the label band would slip over it.”
Due to the lower mass in the ball bearings from igus, these problems are a thing of the past. Here, glass beads are used as rolling elements, which are held by plastic ball races in the bearings. Inner and outer rings of the ball bearings consist of high-performance plastics, which are distinguished by excellent friction and wear values.
“Another advantage is the lubricant-free property of the ball bearings thus eliminating the need for maintenance,” says Mr Meissner. “Both we and our customers can be rest assured that the guide rollers are functioning as we want.”
The next step beyond just the ball bearings is already being planned for: “We will soon be using our new system solution as guide rollers,” explains Bernhard Hofstetter, field staff at Igus. “This system solution consists of a light, clear anodised aluminium tube and two flanged ball bearings.”
For these guide rollers, the company also offers on its website a configurator, with which the user can configure their components easily with a few clicks and order online. This complete solution saves considerable installation time, because the guide rollers are preassembled.
“This solution would of course be easier to use, because no holding fixture needs to be manufactured separately and everything is supplied from a single source,” says Mr Hofstetter. This is very interesting for a series application such as the film storage of the sleeve labeller from Krones.
Even though they see itself as a manufacturer of special machines and supplies custom-made products, the individual modules of a bottling plant is structurally identical, such as in the case of labelling units.
Virtually The Entire Range Of Products In Use
In the Krones bottling plants, more than just the xiros plastic ball bearings are used—almost all products from the range of lubricant-free bearing systems are incorporated. These range from linear and plain bearings to plastic threaded drive nuts. The freedom from lubricant is a crucial factor, particularly in the food industry.
“Here, a contamination of food with fats or oils must be avoided in all cases,” says Mr Hofstetter. “Another plus point is that moisture or chemicals cannot damage our plastic products and thus the cleaning process of machinery and equipment require no special attention.”