Experimental Determination of the Coefficient of Friction in Rotational Sliding Joint

Abstract

The friction processes as the most often physical phenomena cause many negative effects in production systems, and man try to minimize them. Coefficient of friction is one of the fundamental parameters which characterizes the process of friction between two parts, which perform mutual sliding of movement. Its measurement is realised using the experimental methods. In our experiments motion of samples is enforced motorically and various measurement sensors that monitor variables characterizing the process of friction are used. Experimentally obtained values of the coefficient of friction for the bushing aluminium - steel pairs are analysed in the paper. During the run up the value of the coefficient of friction sharply decreased from 0.8 to size 0.1 and then was stable till the end. Experimental tests were realised on the equipment Tribotestor M' 89, which was used for determination of the tribological parameters of bearing bushings. Following input variables were adjusted: the sliding speed, loading of rotanional sliding joint and duration of the test. The temperature in the contact surface of bushings and the roughness parameters (Ra, Rz) were also monitored before and after the tests.

The Size of the Friction Coefficient of the Sliding Pair Depending on the Lubricant Used

“…Parameters of oils Castrol Manual EP 80W and Madit PP90 are listed in Table 2. On the base of measurement of the friction force, the known loading force and the other necessary parameters, the friction coefficient µ is calculated by the software of the experimental equipment [11]: Each pair of bushings was subject of three tests during which the input and output parameters were measured. Value of sliding speed v was constant during whole duration of the test t, always (v = 0.8 ms -1 , t = 1620 s).…”

The Dependence of the Friction Coefficient on the Size and Course of Sliding Speed

“…2) and the motion of samples (internal bushing) is caused motorically. Load force is limited by step-driven electromotor and screw gear [4,5]. F n -loading force, F t -force of friction, a -arm, r -outer radius of the internal bushing, Q -sensed force of friction…”

Investigation of Stress State and Contact Pressures in Contact Area of Journal Bearing by Numerical Simulation

“…It changes with change of materials and operating conditions. For example a hard steel surfaces under atmospheric conditions have value of the friction coefficient approximately f = 0.6, while in the vacuum can be the friction coefficient more than twice greater [1,4,7]. If between friction surfaces is no lubricant or it is not ensured a sufficient lubrication we can say that this condition of the friction is boundary.…”