Equipment for ploughing, the so-called cultivators, which were primarily used earlier for weed control. Today, its main use is to loosen up the arable land to mix organic matter and prepare for the next season. The "Karat 9" of the company Lemken GmbH & Co. KG is an intensive cultivator. Lemken uses lubrication-free plastic plain bearings from igus® in the bearing points, for which the subsequent lubrication can be eliminated completely.
Lemken GmbH & Co. KG was founded in 1780 and has since remained a family-run company that specialises in the production of agricultural machinery for tillage, sowing and plant protection. Lemken now employs over 1,000 employees worldwide, important markets being France, Canada, Russia and China besides Germany.
A division covers equipment for ploughing, known as cultivators, and compact disc harrows. These are now used mainly for conservation tillage and cultivation. With the "Karat 9", Lemken offers an intensive cultivator which penetrates between five and 30 centimetres deep into the ground and thus incorporates organic matter perfectly. During use, it is possible that large stones can be in the path of the tractor and its tillage equipment. For this reason, the Karat 9 has maintenance-free overload elements, whereby the tines, which work on the ground in normal operation, automatically dodge backwards and upwards and then automatically return to the working position. The overload element is maintenance-free with the use of lubrication-free plastic plain bearings from igus® GmbH in Cologne. "Insufficient lubrication was a real problem for applications in the cultivators," says Lars Heier, Director of Marketing at Lemken. "With metallic solutions the bearing points had to be lubricated once a day, so that the bearings can perform their duties properly. This constituted, depending on the working width of the cultivator, up to one hour of work per day. " The iglidur® high-performance materials from igus® don't require a subsequent lubrication at all, because self-lubricating solid lubricants are already incorporated in the bearings. At the same time the iglidur® plain bearings easily withstand the high forces in the overload element of the cultivator.
In 2008, the Karat was the first application by Lemken implemented with lubrication-free iglidur® plain bearings. Earlier Lemken used DU bushings in its machines. "All laughed at us about the Karat cultivator in the beginning, because we wanted to use plastic at the bearing point," Lars Heier admits. "Today, the plastic plain bearings have to be replaced only every few years depending on the load, which accounts for, in addition to the lubricant saved, an additional cost advantage. " After this pioneering project, numerous other equipment from Lemken were equipped with iglidur bearings. The collaboration between the two companies worked very well in the process: igus® tested their own materials very extensively in the in-house test laboratory in Cologne, where various bearing materials are combined with different shaft materials in order to calculate coefficients of friction and wear as precisely as possible. Moreover, Lemken tests the products specifically for their needs at its own site. "It is of much value for us to work with a company from the area. Because, it is possible to sit together without losing time and without complications to discuss new projects or to try new solutions," says Lars Heier. In order to respond to customers at their sites, igus® employs qualified experts in the field who stand by local customers. In addition, there are industry specialists at the headquarters in Cologne who work closely focused on their respective areas and support projects, including in the agricultural sector.
igus® is also happy with the uncomplicated cooperation and the openness of an agricultural undertaking to use plastics technology. "I think it's great that Lemken also 'admits' that they use plastic at bearing points," says Florian Blömker, technical field staff at igus®. "Because, plastic is often looked upon with suspicion in agriculture. And if a bearing point no longer has to be lubricated, the users are often skeptical."
High forces are often at work particularly in agriculture with the use of heavy equipment, which need to be very rugged. Therefore, in earlier times, metallic bearings were the first option. These bearings have a very limited service life, especially with pivoting movements, because lubricants may not be evenly distributed and the same points on the bearing are stressed again and again. Here, plastic plain bearings display their advantages, as pivoting movements do not harm them and there is no lubricant to displace. Another advantage lies in the dry operation of the bearings, since dirt cannot accumulate on them. igus® can bank on 47 catalogue materials for the most varied requirements, such as for heavy-duty applications found in the agricultural sector. Plain bearings from the all-rounder iglidur® G prove themselves in the cultivator Karat 9, by withstanding a compressive strength of 80 MPa. For higher loads igus® also provides, for example, catalogue materials up to 120 MPa, such as iglidur® Q2 or iglidur® TX1 up to 250 MPa. In addition to the standard range, more than 100 special solutions are also available, with which more specific applications can be implemented.
Lemken is certain that it wants to rely on the advantages of lubrication-free plastic plain bearings for future applications. "The working time saved by using maintenance-free bearings, is a very strong argument for plastic plain bearings today," says Lars Heier. "In the future we will continue to rely on the plain bearings from igus®. For what has been proven is retained by us, that is certain. “