2 years ago

MDA Technologies 5/2016

MDA Technologies 5/2016

Lubrication systems to

Lubrication systems to reduce the total cost of machine ownership MACHINE ELEMENTS Inadequate lubrication for bearings is a frequent cause for machine breakdowns. Here, lubrication experts can add an extra edge in terms of reliability and operating life of bearings in any sort of application. 70 µ, that’s the approximate diameter of a human hair. The distance between the rolling element and the raceway in a rolling bearing is typically only 1 to 3 µ. This small gap is extremely vital because this is the space that contains the lubricating film that prevents steel-to-steel contact, thus minimizing friction and wear. With the right lubrication system, run time for the rolling bearings increases significantly and thus machine downtime is reduced. But it is important to define what the “right” lubrication is. Does it mean the more lubricant the better? Does it mean expensive lubricants are a better choice? The answer to these questions depends on the system requirements that the lubricant has to fulfil in a rolling bearing, a linear unit or a bush. These requirements are based on the bearing design, the mounting position and the operating conditions. Three examples show how different the result of such an analysis can be: n A simple electric motor widely used in production facilities often has two deep groove ball bearing supports. Even with 24/7 operation, 90 % of the motors reach their maximum run time, which can be several years, with a simple grease and without re-lubrication. n The bearing supports of dry cylinders in paper machines are faced with greater challenges: The factor that limits the life of these double-row rolling bearings, most of which have angular adjustment, is the lubricant. Often, oil lubrication is the only way to reach the required bearing life of 20 years. Given the high speeds and temperatures in this application, oil is primarily used for heat reduction in order to protect the bearing from overheating. n Wind turbines demand a service life of 20 years for bearing supports. Their operating conditions include low rotary frequencies, particularly on the main bearing and on the gearbox input side, dynamic loads and large differences in temperature all require specially developed greases. These requirements that are specific to an industry and sometimes even to an application are something that rolling bearing manufacturers know well because they are also the parameters that decide the bearing design. Well established companies, like Schaeffler have a line-up of experts to offer support with lubrication problems and develop lubrication systems customized for a specific application. Ensuring high machine availability The interaction of the bearing and the lubricant is what ultimately determines the life of a bearing and also essentially defines machine availability. Schaeffler has researched this interaction for years and continuously develops its range of lubricants. Over time, thousands of test stand runs used to test greases in rolling bearings with regard to service life, friction and wear, have resulted in a tried-and-tested grease program that has been established on the market under the “FAG Arcanol” brand. This program distinguishes between multipurpose greases that are suitable for a wide range of applications, heavy-load greases (used, for instance, in main bearings in wind turbines), high-temperature greases (up to 200 °C) and special greases developed for specific applications (e.g. for spindle bearings in machine tools). Complex applications such as rolling bearings, in particular, require lubricants that deliver proven and consistently MDA Technologies 5/2016

MULTIMEDIA CONTENT An overview about the Arcanol rolling bearing greases 01 FAG Concept2 and Concept8 automatic re-lubrication systems high performance. The ever increasing requirements for bearing supports - such as the more compact design of accessory drives, higher loads and speeds - environmental aspects and constant changes on the commodity markets require the continuous advancement of lubricants. In 2015 alone, Schaeffler carried out over 50,000 hours worth of tests on its in-house FE8 and FE9 test stands. Automatic re-lubrication systems Besides the initial selection of a suitable lubricant, re-lubrication is also a vital aspect of a lubrication system: When and how much do you need to re-lubricate? Once this has been defined for an application, lubricant dispensers or systems can ease the maintenance staff’s workload considerably. Automatic re-lubrication devices provide fresh lubricating grease to the contact points of the rolling bearing in the desired quantity and at the right time. These devices follow predefined lubrication and maintenance intervals and avoid the use of too little or too much grease. Overall machine downtime and maintenance costs are reduced as a result. Re-lubrication devices are selected for specific bearing positions. They can be used for a wide range of applications, including electric motors, gearboxes, pumps, compressors and ventilators, linear systems, conveyor equipment, and machine tools. The “FAG Concept2” and “FAG Concept8” lubricant dispensers can supply up to 2 and 8 lubrication points respectively. If the Concept2 is equipped with 2 pump bodies, it can supply 2 lubrication points with different requirements. For instance, electric motors often include cylindrical roller bearings and ball bearings - but a cylindrical roller bearing requires an average of 4 times more grease than a ball bearing. The Concept8 allows connection of up to 4 pump bodies that supply 2 lubrication points each with the same requirements. The lubrication devices are supplied with voltage via a power supply unit (Concept2 can also run on a battery) and work autonomously. They can also be controlled externally and are easy to integrate into machine operation. For maintenance personnel, automated re-lubrication devices mean considerably less work, improved operating reliability and often reduced maintenance costs. Photographs: Schaeffler AG About Schaeffler AG The Schaeffler group is a leading integrated automotive and industrial supplier. The company based in Herzogenaurach, Germany, generated revenues of approximately Euros 13 billion in 2015. With around 85,000 employees, Schaeffler is one of the world’s largest family owned companies. The technology group has more than 170 locations in 50 countries with a worldwide network of manufacturing plants, research and development centers and sales subsidiaries. The Schaeffler group makes key contributions towards “mobility for tomorrow” with precision components and systems in engines, transmission, bearings - rolling and plain, along with expert lubricants and lubrication systems for industrial applications. 02 FAG Concept2 re-lubrication device on an electric motor MDA Technologies 5/2016


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