Fretting corrosion
In mechanical engineering, fretting corrosion is a sign of wear that can be traced back to fretting corrosion and tribo-oxidation .
The cause of fretting corrosion are micro-sliding movements in the highly stressed contact between two components, which often occur if the excess is too small . Fretting corrosion is also favored by inadequate lubrication, so it often occurs in boundary or mixed friction conditions . In addition, vibration stress contributes significantly to the formation of fretting corrosion, which is why this wear phenomenon is usually classified in the category of vibration wear. Accordingly, the tribochemical reaction that leads to the formation of fretting corrosion stops immediately when the supply of vibrations is interrupted. When two steel surfaces come into contact, as often occurs in classic mechanical engineering, reddish iron oxides (Fe 2 O 3 ) are initially formed , which can turn black when converted to Fe 3 O 4 . For the formation of fretting corrosion, however, it is sufficient if one of the contact partners contains iron . For example, fretting corrosion also occurs in the steel / bronze contact and in some other material pairings.
Fretting corrosion occurs primarily in shaft-hub connections in the field of classic mechanical engineering. Examples of this are bearing seats on a shaft or in a housing, seats of gears on a shaft or key connections of all kinds. In the latter, reversing operation, i.e. frequent reversals of the direction of rotation, promotes fretting corrosion and thus the formation of fretting corrosion.
The best constructive measure to prevent fretting corrosion is to provide a sufficient tight fit. Conventional lubricants, on the other hand, are usually not suitable for preventing fretting corrosion, as they do not provide sufficient lubrication performance with the oscillating frictional movements. For this reason, mostly white, grease-like pastes that contain solid lubricant particles or special coatings are used.
Individual evidence
- ↑ SKF GmbH: Avoid bearing damage and save a lot of money . Online at evolution.skf.com; accessed on August 12, 2017.
- ^ NSK Europe Ltd .: Damage types - fretting corrosion . Online at www.nskeurope.de; accessed on August 12, 2017.
- ↑ a b Winix GmbH: White solid lubricants . Online at www.winix.de; accessed on August 12, 2017.
- ↑ a b Getriebebau NORD GmbH & Co. KG: The formation of fretting corrosion between the hollow gear shaft and the plug-in shaft (PDF; 330 kB). Online at www.nord.com; accessed on August 12, 2017.
- ↑ SKF GmbH: Paste to prevent fretting corrosion (assembly paste) . Online at www.skf.com; accessed on August 12, 2017.
- ↑ OKS Spezialschmierstoffe GmbH: Pastes ( Memento of the original from July 19, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Online at www.oks-germany.com; accessed on August 12, 2017.
- ↑ Higher performance through coatings - coated roller bearings and precision components ( memento of the original from January 4, 2017 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.71 MB). Online at www.schaeffler.com; accessed on August 12, 2017.
