Fretting wear

Excessive lubrication Fatigued race or rolling elements Fretting wear Contamination by Inadequate abrasive or lubrication corrosive materials Grease churning due to too soft consistency... 

The main factors which influence fretting wear can be classified as in the following paragraphs, but as more data become available, it is apparent that a greater measure of interdependence exists than might be indicated by such a simple procedure, and it is becoming less easy to make generalisations. Nevertheless, even with this reservation in mind, it is useful as a first step to list some of the more important factors. 

The effect of hardness is complicated, but like most wear processes an increase in hardness generally leads to a reduction in fretting wear at room... 

Fretting wear, along with most other wear phenomena, is not a process that can be defined in terms of any single mechanism. It consists of a series of events, many of which are common to other wear processes and which may assume greater or lesser significance depending upon the precise nature of the operating conditions, materials and environment. 

Fretting wear is observed in systems where two surfaces perform an oscillatory relative sliding with small amplitude (= fretting). This is often due to vibrations. In principle the same wear behavior as for normal sliding, should occur. However, wear particles tend to remain within the immediate contact region where they can act as an abrasive and lead to increased wear. 

Kang C, Eiss NS, Jr. (1992) Fretting wear of polysiloxane-polyimide copolymer coatings as a function of varying humidity wear. Wear 158(1—2) 29... 

Evidently, fretting is worse in air than in an inert atmosphere.25 There is less damage in a humid atmosphere than in dry air since humidity can have a lubricant action, and the hydrated oxides are less hard than the dry oxides.25,90,93 Surfaces subjected to fretting wear have a characteristic appearance with red-brown patches on ferrous metals and adjacent areas that are highly polished because of the lapping quality of the hard iron oxide debris. 

The fretting wear rate is directly proportional to the normal load for a given slip amplitude. However, in the total-slip situation, the frequency has little effect. (Water-house)88 In a partial-slip situation, the frequency of oscillation has little effect on wear rate per unit distance in the low-frequency range, whereas the increase in the strain rate at high frequencies leads to increased fatigue damage and increased corrosion due to a rise in temperature.75... 

Prevention. Various design changes can minimize fretting wear. The machinery should be designed to reduce oscillatory movement, reduce stresses or eliminate two-piece design altogether.75 Some examples of possible approaches to consider are ... 

Waterhouse, R.B., Fretting Wear, Proc.Int. Conf.onWearofMaterials,ASME,NY,pp. 17-22,1981. 

Keywords Contact mechanics Contact stiffness Fretting wear Mindlin model Nonlinear mechanics Quartz crystal resonator Quartz crystal microbalance ... 

A key factor in predicting eventual flow-induced vibration damage, in addition to the above mentioned excitation mechanisms, is the natural frequency of the tubes exposed to vibration and damping provided by the system. Tube vibration may also cause serious damage by fretting wear due to the collision between the tube-to-tube and tube-to-baffle hole, even if resonance effects do not take place. 

Human blood with particles from a fretting wear tester Ti Zr Digest in closed PTFE container with HNO3/HF (to dissolve Ti, TiOj and ZrOj [WDCCV] Direct determination with PE Model plasma 2000 ICP-AESr (dual monochromator) [ICP-AES] [WDCCV-ICP-AES] Kunze et al. (1998)... 

For systems consisting of common materials (e.g., metals, polymers, ceramics), there are at least four main mechanisms by which wear and surface damage can occur between solids in relative motion (1) abrasive wear, (2) adhesive wear, (3) fatigue wear, and (4) chemical or corrosive wear. A fifth, fretting wear and fretting corrosion, combines elements of more than one mechanism. For complex biological materials such as articular cartilage, most likely other mechanisms are involved. 

Fretting wear occurs at the interface between two closely fitting components when they are subject to repeated slight relative motion (slip). The relative motion may vary from less than a nanometre to several micrometres in amplitude. Vulnerable... 

Figure 7.51 Location of fretting wear in some common engineering components. (From Batchelor et al. [7.46].)...

Waterhouse RB. The effect of environment in wear processes and the mechanisms of fretting wear. In Suh NP, Saka N, editors. Fundamentals of Tribology. Massachusetts The MIT Press, 1978 567-584. 

Figure 5. Crystallite size and environmental effects on fretting wear of AI2O3-AI2O3 couples.

Figure 6. Increasing grain size promotes grain boundary fracture and grain pull-out (fretting wear in dry air cf. Fig. 5). Average grain sizes (a) 3 pm (b) 1.6 pm (c) 0.6 pm (bottom) [11].

Figure 5 shows investigations of the fretting wear of alumina depending on the environmental conditions, submicrometer ceramics may exhibit a wear rate which is an order of magnitude lower than measured for conventional AI2O3. It is important to understand that this improvement is not only a simple consequence of the increased hardness, but is also associated with reduced grain pull-out in the wear track of the submicrometer material (Fig. 6) [11]. 

A. Krell and D. Klafike, Effects of grain size and humidity on the fretting wear in fine-grained alumina, Al203/TiC, and zirconia, J. Am. Ceram. Soc. 1996, 79, 1139-1146. 

R. B. Waterhouse, Fretting wear, in ASM Handbook, Vol. 18, Friction, Lubrication, and Wear Technology, ASM International, Materials Park, OH, 1992, pp. 242-256. 

Fretting Wear Generated by a relative oscillatory tangential movement of... 

---