Analysis of fretting corrosion in machine elements

Heavy duty machines, which are applied in coal mines, operate at extremely heavy environmental conditions. Their technological process of operation is characterised by variable loads during mining or transport which makes it necessary for these machines to have very high durability. In some cases, the operation of machine elements can be interrupted by failure. The reasons for such failures may be various. The machine's vibration generates relative micro displacements. After a comparatively short period of operation, the wear occurs on the surfaces of connected machine elements. This type of wear results from the occurrence of a complex phenomenon called fretting. There are different types of fretting, such as fretting‐fatigue, fretting‐wear, fretting‐adhesion and fretting‐corrosion. The last one is a special kind of machine element damage occurring on the surfaces of contacting elements loaded by pressure and simultaneously subjected to relative and small oscillation movements. Fretting is generated on condition that there exists a displacement between two contacting surfaces, the amplitude of which ranges from a few to tens of micrometres. Furthermore, some number of slip cycles and the normal load are indispensable. It is possible to find the expression for the dependence determining the amplitude of oscillation movements in the joint between two machine elements. The paper describes the mechanism and analysis of fretting corrosion, gives some examples of surface destruction and presents the amplitude of oscillation movements as well as the results of investigations into fretting in the cylindrical joints, e.g. pin joints applied in heavy duty conditions in coal mines such as in the case of suspension of hoisting devices. Copyright © 2007 John Wiley & Sons, Ltd.