Heavy loads easily mounted

• igus introduces iglidur tribopolymer plain bearings, which are maintenance-free and lubrication-free, suitable for heavy-duty applications in construction and agricultural machinery.

• The new iglidur material reduces the need for lubrication, preventing environmental contamination and lowering maintenance costs.

• igus has developed a GKF shaft with optimized corrosion protection and wear reduction, ideal for heavy-duty environments.

• The company offers over 60 materials, including the versatile iglidur G, which can handle high loads and is suitable for various applications.

• igus conducts extensive testing on its products, including high-load endurance tests, to ensure reliability and predict service life.

• The isense product range from igus provides condition monitoring for plain bearings, allowing for planned maintenance and preventing unexpected failures.

iglidur tribopolymer plain bearings reduce the use of lubricants and ensure maintenance-free operation

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The trend in the construction and agricultural machinery industry shows that users want to save money and significantly reduce maintenance. Replenishing lubrication is one of the most time-consuming and expensive operations - and one that can also release grease into the environment. Many users are therefore looking for maintenance-free and lubrication-free plain bearings that demonstrate a long service life even under harsh heavy-duty conditions. Dry-operating iglidur plain bearings from igus are suitable for precisely these scenarios. The product range has now been supplemented with a new material especially for heavy-duty applications.

When servicing construction and agricultural machinery, lubricating the bearing points is one of the most time-consuming tasks. The damage can be extensive if regular lubrication is neglected. Insufficiently lubricated and maintained bearing points cause damage to expensive shafts and machined ends which can impair the function of important machine parts. In the worst case, there is a risk of machine failure. It is often necessary to replace not only the bearings concerned but also adjacent assemblies. These failures are costly and occur at the most inopportune times and jeopardise operation and project schedules. Failures and maintenance-related downtimes due to insufficient lubrication can be reduced. In the case of metallic bearings this can be done by central lubrication systems that continuously supply the bearing positions with grease. However, these systems are associated with additional costs and require additional maintenance, and not all bearing positions can be reached in this way. No matter how lubrication is done, there are always large amounts of grease involved. These lubricants are expensive and ultimately end up in the environment. "We are talking about significant amounts of grease that are released into our environment year after year through lost lubrication. Depending on the size of the machine,quantities in the metric hundredweight range are being released. This is causing many users to rethink more and more," explains Uwe Sund, Product Manager Heavy Duty Bearings at igus GmbH in Cologne. Due to their well known properties, lubricated metallic bearings are well established in the field of high loads. Until now, there was no way around grease - on the one hand it''s necessary for the function of the bearing, and on the other hand it protects the shaft from corrosion. Therefore,if a switch is to be made to a lubrication-free and maintenance-free solution, the nature of shafts and fixtures must also be taken into account. Corrosion protection waxes or nitrided surfaces can be cost-effective and efficient solutions.

Felt as a seal for the bearing

For over 30 years, igus has been producing plain bearings made self-lubricating, high-performance plastics. The solid lubricants are already incorporated into the tribopolymers. They make construction and agricultural machinery free from maintenance and grease. It is important that the bearings can operate in a corrosion-free environment, because by dispensing with lubricant, the shaft and fixture are no longer protected by grease. A one-to-one replacement is therefore not possible for all bearing positions. If the shaft has to be lubricated once, igus can come up with iglidur plain bearings that are manufactured with a felt seal. This ensures that the grease remains in the bearing position, i.e. it does not leak out. At the same time, the seal protects against the penetration of sand and dirt. In the case of completely dry operation, the use of hard-chrome plated or nitrided surfaces is recommended. For this purpose, igus has now developed a GKF shaft that has a surface optimised for corrosion protection and wear reduction. Their use is particularly suitable in heavy-duty environments.

Heavy-duty = heavy load?

"Many equate heavy load with heavy-duty, however high load is only one part of heavy-duty. This term refers to particularly extreme demands on the plain bearings, and these do not always have to be high loads. Moisture, dirt, shocks, vibrations or even edge loads are also extreme challenges for the bearings," clarifies Uwe Sund. Applications in which only high loads occur without additional stresses such as edge loads or impacts can be solved with universally applicable all-rounder materials from the iglidur range. For special application areas in which combinations of extreme cases occur, igus falls back on a wide variety of special materials specially adapted to these requirements. igus has over 60 materials for the most diverse applications in its range. For many of these special requirements, igus has developed all-rounder materials, such as the tried and tested iglidur G material, which can absorb forces of up to 80MPa. All materials from igus are characterised by their dry-operating properties as well as the service life that can be calculated in advance. They are insensitive to dust and dirt, which makes them ideal for use in the area of construction and agricultural machinery as well as in commercial vehicles. They are also lightweight and cost-effective due to their production by injection moulding.

High-load test rig at igus: plastic compared to metal in endurance test

igus tests all of its motion plastics on 3,800 square metres. The spectrum ranges from movements in all directions for e-chains and chainflex cables to linear, pivoting or rotational movements for various bearing types. igus has set up its own test rigs especially for high loads, and certain application scenarios. These are reproduced one-to-one for load cases such as edge/impact loads. For example, there is a front loader situated outdoors that moves 24 hours a day, seven days a week, in all weather conditions. With the data obtained in the various tests, plain bearing solutions are compared with the optimum products for the respective heavy-duty application. A direct comparison between plastic and metal bearings, for example, is also possible. In the front loader test rig, for example, four cycles per minute are run, and the resulting speed depends on the pivoting angle of the bearing position. The test duration is about two weeks. Daily visual inspections ensure that the front loader is not damaged if there is failure of a bearing.

The tests enable the precise determination of the service life of the products. The results of the tests are added to the database, and the igus online configurators predict the expected service life of the selected components. The tests and real customer experience show that many applications, with higher loads of 30 to 80MPa, can already be implemented with the all-rounder materials from injection moulding. The Polish company Demarko uses iglidur G in an oscillating axle for an articulated lorry trailer. In this project, the focus was on operation without lubrication. This goal could be achieved by the application of the iglidur G material. The same tribopolymer is also used in the bearings of the tines in the cultivators from Lemken. For even higher dynamic forces, igus brings the coiled materials TX1 and TX2 into play.

Heavy-duty bearings made from wound filament

With TX1 and TX2, igus has developed two plain bearing materials made of high-strength woven fabric. They are used where particularly high loads occur and when injection-moulded plain bearings reach their load limits. Here, the extremely high tensile strength filaments, specially interwoven ensure maximum resistance. "Both materials can be used to implement applications where forces of up to 200MPa have to be absorbed. The decision between the materials depends on the condition of the shaft surface", explains Uwe Sund. The difference between the two materials is primarily in the structure of the plain bearings made from them, which leads to varying wear behaviour. Both types were extensively tested on the indoor and outdoor test rigs. Swivel tests showed that iglidur TX2 plain bearings in conjunction with hard-chromed shafts are about 3.5 times more wear-resistant than plain bearings made of iglidur TX1. On the other hand, shafts such as those without additional surface treatment or coating but with bearings made of iglidur TX1, deliver better results. Since both materials are very resistant to temperature, chemicals and humidity, the plain bearings can be used in many other areas: like iglidur TX1 in this year's winner of the golden manus, Kässbohrer Geländefahrzeug AG. The manus award honours the best plain bearing applications worldwide every two years. The company relies on TX1 in its PowerBully, an off-road vehicle for disaster control. The heavy-duty plain bearings are located in the oscillating and tensioning axles.

Wear detected in time by integrated intelligence

For its plain bearings, igus also presents solutions for condition monitoring. For this purpose, the motion plastics specialist offers the standard isense product range. The aim is to have the sensors in the bearings detect wear in extremely stressed applications, in advance, and give the user a signal in good time if the bearing is at risk of failure. This means that maintenance can be planned and does not take the operators of agricultural machinery by surprise during the harvest season. "We have developed smart iglidur especially for hard-to-reach bearing locations and applications where regular maintenance intervals are not planned," reports Richard Habering, Head of the Business Unit smart plastics at igus GmbH. The measured data from the sensors can be integrated in a variety of ways by the machine and plant operators. igus offers three readout units for this purpose: either the user can manually read out all plug-in points, or install a control unit with a red/green display on the machine, which provides information about the condition of the plain bearings. Another option is the connection to the i.Cee:local. For this purpose, a radio module sends the sensor data wirelessly to the i.Cee:local. The integration of data to the IoT, cloud system or to the customer network is possible on a wire-bound basis. "This gives the customer the freedom of choice to read out the data in the way that suits them best," emphasises the smart plastics expert.