Pin-on-disk tribometer

Classical, macroscopic devices to measure friction forces under well-defined loads are called tribometers. To determine the dynamic friction coefficient, the most direct experiment is to slide one surface over the other using a defined load and measure the required drag force. Static friction coefficients can be measured by inclined plane tribometers, where the inclination angle of a plane is increased until a block on top of it starts to slide. There are numerous types of tribometers. One of the most common configurations is the pin-on-disk tribometer (Fig. 11.6). In the pin-on-disk tribometer, friction is measured between a pin and a rotating disk. The end of the pin can be flat or spherical. The load on the pin is controlled. The pin is mounted on a stiff lever and the friction force is determined by measuring the deflection of the lever. Wear coefficients can be calculated from the volume of material lost from the pin during the experiment. 

The pin-on-disk tribometer experiments in this work have thus revealed that the Mctirmal properties of the SAM films observed by AFM could be reprmluced on a macros scopic contact scale by employing a hydrophilic elastomeric slider. 

Figure 7. Friction force versus load plot (pin-on-disk tribometer) of buffer solution only (0)> PLL(IO) in buffer solution (Q), and PLL(10)-g[2.9]-PEG(2) in buffer solution ( ) (ball = steel (6 nun in diameter), disk = glass, buffer solution = 10 rriM HEPES (pH 7.4), concentration of the...

Figure 3. A schematic illustration of the pin-on-disk tribometer and the location of the two different fluorescently labeled PLL-g-PEG copolymers (fluorescein isothiocyanate (FITC-PLL-g-PEG), pre-coated onto both pin and disk, RBITC-PLL-g-PEG, in the lubricant solution, dissolved in HEPES buffer).

A pin-on-disk tribometer (CSM Instruments, Switzerland) was employed to investigate the lubricating properties of the polymer solutions under pure sliding conditions. 

To evaluate the lubricating properties of PLL-g-dex copolymer solutions and compare them with other standard aqueous solutions, including HEPES buffer solution, dextran solutions (dex(5.2)), as well as PLL(20)-g-PEG(5) solutions, coefficient of friction (fi) versus speed plots were acquired under both sliding and mixed sliding/rolling conditions using a pin-on-disk tribometer and MTM, respectively. 

After the preparation of the PMAA brushes, their lubrication ability under low contact pressures was tested in a neutral aqueous solution. It was shown that the macroscopic friction between polyelectrolyle bmshes of different molecular weights and soft, hydrophilic ox-PDMS pins was below the detection limit of the employed pin-on-disk tribometer over the entire speed range tested. While the PMAA bmshes could not be distinguished with n vs sliding speed plots, the long-term stability of short 15 nm PMAA bmshes was shown to be inferior to long bmshes (240 nm dry thickness). A further comparison between... 

Pin-on-disk tribometers (CSEM, Neuchatel, Switzerland) were used to measure macroscopic frictional forces under pure sliding conditions. Two tribometers operating in different speed ranges were employed to enable the sliding speed to be varied over a wide range. The slower tribom-eter measures frictional forces in the speed range of 0.1-20 mm/s and the faster tribometer from 25 to 400 mm/s. A fixed pin that holds the steel ball (diameter = 6 mm, DIN 5401-20 G20, Hydrel AG, Romanshom, Switzerland) was... 

Fig. 6 Coefficient of friction (fi) versus number of laps for sliding contact between a steel pin and a glass disk in a pin-on-disk tribometer. a For HEPES solution as lubricant fluid b For 50 vol.% glycerol in HEPES as lubricant fluid. Case II concerns the tribopair pre-incubated in an aqueous-polymer-containing glycerol solution, while the solution in the cup does not contain any dissolved polymer. In Case ID, the surface was also pre-coated with polymer in a similar way, and also the solution in the cup contains the polymer at a concentration of 0.25 mg/ml. Case IV represents surfaces that are similarly pre-coated with polymer but the polymer concentration of the solution in the cup is changed from 0 to 0.25 mg/ml following the injection of the polymer solution into the cup at the 13th lap (load = 2 N, sliding speed = 5 mm/s and track radius = 3 mm)...

The pin-on-disk tribometer can be modified by replacing the rotating disk motor with a one-directional reciprocating table as shown in Fig. 2.19. This arrangement reproduces the reciprocating motion typical in many real-world mechanisms. The configuration of... 

Figure 2.17 Pin-on-disk tribometer equipment. Photo courtesy of Nanovea Corporation.

Figure 4.1. Progressive loading test on a pin-on-disk tribometer with U = 0.19 m/s pin compound material (sintered bronze/PTFE with lead additive) disk steel...

A pin on disk tribometer was used to evaluate the wear of the treated and untreated regions. The disks were set on the turntable driven at 12 mm/second for 10 minutes. A constant normal load of 50 grams was applied by JIS G3539SWCH10R pin material. 

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