Pre-rolling Friction Moment Measurements of Corundum and Silica Balls on K8 Glass Surface

Ultraprecision positioning to better than nanometer in accuracy is of a great interest in various applications. The paper reports on recent pre-rolling experimental measurements of the moment friction during the phase of pre-rolling, i.e., at the start and at the finish. To discuss the case properly, the experiments are set for pure rolling without any external effect nor any slippage at the contact patch. The pendulum was designed to secure pure pre-rolling without slippage. Beside the fact that the experiments have shown extremely low values of rolling coefficients in the order of (× 10^–7), it is possible to establish the appearance of real hysteresis curves showing the dependance of the friction moment on the displacement. The sensitivity of the measurement of rolling friction moments is in the order of 10^–10 Nm, the measurement error does not exceed 10% with 125 nm minimum displacement of the ball peel adhesion density evaluated as 2.2 × 10^–4 J/m².