Design and hygiene reasons

Tribo-optimised polymer bearings for thermo-forming packaging machinery

The issue of performance plays a significant role in the food packaging process. Since machine runtimes provide very little room for improvement, shorter cleaning and maintenance intervals are now moving into the spotlight. Lubrication and maintenance-free polymer plain bearings are proving themselves in this demanding environment. This is due to design and hygiene considerations.

"We supply customised machine solutions that are fully adapted to the needs of our customers," explains Hans-Günter Donges. The product engineer has lead responsibility for developing the "PowerPak" thermoformer, the flagship of the international CFS B.V. Group. "The design of this packaging machine created a worldwide uproar. Customers are able to materialise potential savings in the six-digit range. " The CFS site in Biedenkopf-Wallau develops and produces primarily thermoforming machines, which are mostly used in the food industry and for the packaging of medical disposables. "Our 'Lifecycle Performance' product philosophy supports current and future requirements of the food processing industry, allowing performance to be increased while costs are lowered," is how Donges accentuates the CFS concept. The topics of versatility, flexibility, cost-effectiveness, food safety, and environmental protection are central for this packaging technology company. These are the core requirements for all product developments.

Developing products as part of a dialogue

The requirements for suppliers are accordingly high. On the one hand, quality and on-time delivery play an important role. But on the other, the topic of technical collaboration is equally relevant. "We involve our suppliers early during the product development, and develop an appropriate solution as part of a dialogue", the product engineer confirms. The packaging specialist has been working together with igus® GmbH for many years. Hans-Günter Donges: "For instance, during the development of the thermo-former, the focus was on keeping maintenance to a minimum at a guaranteed machine availability of 99%. This required the use of appropriate machine elements, some of which also needed to be developed. “

Maintenance-free polymer bearings for high machine availability

Tribo-optimised polymer plain bearings made by igus® GmbH, Cologne, from various "iglidur®" materials, "igubal" spherical bearings, "xiros"ball bearings, as well as "drylin®" linear plain bearings are now the state-of-the-art for new product developments. For instance, the safety doors use the cost-effective allrounder, "iglidur® G" and the FDA approved specialist, "iglidur® A 180". The high-tech problem solver, "iglidur® X" for chemicals and temperature applications demonstrates its strength in the pivoting mechanism and the safety hood for the sealing station. But also "iglidur® J", a specialist for low friction values is proving itself in the pivoting mechanism drive, as well as the vertical stroke system. "And last but not least, without the high performance material, "iglidur® Z", the entire development of the toggle lever system would not have been possible in today's version", Hans-Günter Donges explains. Throughout the two-year design engineering phase, many components were sampled, corresponding tests were conducted in the igus® technical lab, and ultimately evaluated on location at the machine, so that the corresponding running performance could be guaranteed. "From the very beginning, we were convinced by the cost-effectiveness and technical properties of the polymer bearings. They are affordable, the customers can completely skip lubrication, and the maintenance intervals for the machine a reduced", Hans-Günter Donges highlights as only some of the advantages. Worldwide, roughly 150 of these "PowerPak" thermo-forming packaging machines are already proving themselves in field use.

CFS Germany: materials, machinery, entire production lines

Roughly 2,000 employees at six national and international CFS production locations provide each customer with a design that matches their packaging task. "We are a specialist for performance-oriented solutions in the food sector. Our product line ranges from packaging materials to stand-alone machines and complete production lines for preparing, marinating, processing and packaging of primarily meats, poultry, fish, seafood, and cheese products", explains Birgit Christmann, head of corporate communications at the Biedenkopf headquarters (Hesse). Approximately 430 employee work here. "We provide our customers with increased lifcycle performance. His needs are determined jointly, and solutions are then developed that are tailored to their specific needs", explains Christmann. This was for instance performed for the thermo-former. Hans-Günter Donges: "This is a from the ground up redesign of the packaging machine. It provides a host of options that raise the bar in terms of performance, cost-effectiveness, flexibility, investment reliability, and hygiene. " The thermo-former has a modular design. "All modules are fully functional units that can be replaced depending on need. " The machine concept facilitates optimum availability over the entire service life, Donges claims.

Hygienic design: Completely grease-free thermo-former

In addition to temperature and cleaning agent resistance, the food industry places the focus primarily on hygiene. Product contamination must be avoided at all cost. Lubricant-free polymer bearings shine in this environment. These are resistant to dirt, grease, humidity, alcalis, and acids. Bearings in thermo-formers are used in all general functional fields that involve adjusting, positioning, rotating, or guiding. They are maintenance-free, rugged, and resistant to chemicals. They will stand up even to cleaning with the most abrasive agents. "Grease is a bacterial carrier that can be distributed on all parts of the machine. This can be extremely hazardous", explains Hans-Günter Donges. "Our thermo-former is the world-wide only machine available today that works entirely free of grease. None of the bearing locations require lubrication. “

Extreme surface pressures and cycle time performance.

The design highlights of the packaging machine are the newly developed toggle lever system, which is used in the forming and sealing station. It integrates the primary guide shafts, which are supported by "drylin®" linear guide liners. The toggle lever bearing support itself is implemented with "iglidur® Z" heavy-duty material. Depending on the overall size of the plant, several toggle lever systems might be in use. The forming station generates extremely high pressures and forces that can reach up to 10 tonnes. The sealing station calls for sealing forces. The bearings in this case are designed for dead centre forces of up to 45 MPa. Both applications also have high cycle rates. These are generally up to 30 cycles per minute on two to three shifts, six days per week. "The polymer bearings need to absorb these high pressures, forces and cycle rates for years", Hans-Günter Donges emphasises. CFS never considered the use of conventional rolling bearings on the toggle lever systems. "These must always be relubricated manually, which increases the risk of product contamination. Moreover, the installation of automatic lubrication systems is a cost driver", the product engineer explains. The lubricant-free polymer bearings have proven themselves from day one. The lever system operates completely trouble-free. And the maintenance intervals are also significantly reduced, which has a positive impact on costs, as is confirmed by the service technicians.

Plastic ball bearings: Reliability due to long-term testing

A new development from igus® bis proving itself in film deflection applications. This application uses "xiros" polymer ball bearings.

Linear stroke of the surplus-film winder Linear stroke of the surplus-film winder with a combination of "drylin®" hard anodised aluminium precision shaft and maintenance-free "iglidur ® J" polymer plain bearings.
Bearing support for the toggle lever stroke (sealing station). Bearing support for the toggle lever stroke (sealing station).
Standardised toggle lever stroke system in the sealing unit Standardised toggle lever stroke system in the sealing station (overall schematic): the vertical guide of the upper stroke is accomplished with "iglidur® J" bushings, the toggle lever bearing is accomplished with the heavy duty material, "iglidur® Z".
Vibration-free energy and "E6" data supply system at the labeling machine. Vibration-free energy and "E6" data supply system at the labeling machine. The bearing support for the deflection rollers is accomplished with "xiros®" polymer ball bearing.
Standardised safety door bearing support Standardised safety door bearing with lubricant-free "iglidur® A 180" plain bearing made by igus®. The plastic bearings are FDA approved.
Primary linear bearing for the lower film tensioner Primary linear bearing support for the lower film tensioner using "igubal®" flanged bearings.
Picture of the involved persons Hans-Günter Donges (left), product engineer at CFS Germany at the headquarter in Biedenkopf-Wallau, Dipl. Eng. (FH) Lars Braun, Packaging Industry Sector Manager at igus® GmbH.

These single row grooved ball bearings provide the desired complete lack of lubricants above the exposed product. In contrast to metallic ball bearings, they are corrosion-resistant and can also be cleaned with ease.

Centrepiece: toggle lever system

"We conducted a host of joint test series and long-term tests during the two year development phase", Hans-Günter Donges recollects. "The collaboration and service worked well at all times. " The on-going optimisation process gives today's end customer the assurance that the running performance of polymer bearings is secured for the entire lifecycle of the packaging machine. "The toggle lever system is the heart of the packaging machine. When it stops functioning, the thermo-former is shut down. This must be prevented at all cost. This is where polymer bearings ensure permanent machine availability.

Here, you can find the products used

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