Dry and lubricated

Plastics. Almost all commercial plastics find some use both dry and lubricated for sliding at low speeds and light loads the most commonly used thermoplastics are nylon, acetal resins, and polytetrafluoroethylene (PTFE). Typical thermosetting resins for bearing appHcations are phenoHcs, polyesters, and polyimides. Table 8 compares the characteristics of plastic bearing materials with those of graphite, wood, and mbber which find use in somewhat similar appHcations. 

The effect of such operating parameters as load and rubbing speed on the quantitative relation of dry and lubricated wear is neither simple nor obvious. Table 13-4 shows two direct comparisons one of data from the work of Kerridge and Lancaster [15] and the other of unpublished data... 

Limited data is available on the wear rate of CVD diamond [90,91]. A recent study has been conducted in order to investigate the basic tribological properties of bulk and thin-film CVD diamond. The sliding wear characteristics of a number CVD diamond materials have been evaluated using a modified Denison T62 abrasion [92] pin-on-disc test rig, operated in dry and lubricated sliding wear conditions, and compared with a typical hardened steel which is often used for wear part components. 

The temperature rise associated with both the dry and lubricated wear tests did not exceed 90°C. Such a temperature rise can be associated with the low coefficients of friction (and carrier mechanisms during the lubricated tests). Such increases are not sufficient to noticeably alter the properties of the CVD diamond or to breakdown the mineral oil lubricant. 

KetaSpire KT-820 SL30—Very good wear resistance, dry and lubricated... 

Applications for PEEK in the aerospace industry include critical engine parts as the polymer can withstand high temperatures and the tribological interaction of dry and lubricated material contacts. In aircraft exterior parts, PEEK provides excellent resistance to rain erosion, while for aircraft interior components, its inherent flame letardancy and low smoke and toxic gas emission reduce hazard in the event of a fire. In aircraft electrical systems, the polymer is used for manufacture of convoluted tubing to protect wires and fibre optic filaments. PEEK is also used to protect the wire harnesses used in commercial aircraft engines. 

The boundaiy between the dry and lubricated parts of the contact is illustrated by fringe interferograms for the 5 m/s case [1], and comparison is made with corresponding numerical results in Figure 7. For the numerical result the area for which the contact remains dry is coloured black. 

A transient munerical analysis has been carried out of the EHL start-up conditions examined experimentally by Glovnea and Spikes [1]. The results show considerable differences when detailed film profile comparisons are made. The transient behaviour of the front between dry and lubricated contact is reproduced, and the numerical results are closely aligned with a simple entrainment transport model. The differences between experiment and theory show an over entrainment of oil into the experimental contact compared to that calculated using the Reynolds equation. A possible explanation for this effect based on an initial sticking of the presumed slipping surfeces is suggested. 

Figures 4a) and 4b) show the variation of forces and coefficient of friction (p) with modulation amplitude, respectively, for A1 6061. Results are shown for both dry and lubricated cutting. The force and p values for a modulation amplitude of 0 pm correspond to the case of conventional cutting. It is seen m Figure 4a) that the cutting and friction...

Figure 4. Variation of a) forces and b) coefficient of friction (p) with modulation amplitude for dry and lubricated cutting of A16061. Modulation amplitude of 0 pm corresponds to conventional cutting. Modulation frequency 75 Hz.

SESSION XXII Tribological Studies of Dry and Lubricated Surfaces (4)... 

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