OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 2 2025 was used to record the displacement of the pin, which is correlated to measure the wear of the material. Additional attachments, such as a pin heater and environmental chamber, are provided for conducting experiments that simulate actual working conditions. Fig. 2 shows the complete experimental setup of the pin-on-disc tribometer. Figs. 2, a–c depict the attachments for pin heating, the testing setup, and the controller with software, respectively. The setup specifications allow for testing within a load range of 0 N to 200 N and a rotational speed range of 200 rpm to 2000 rpm. The pin diameter can range from 3 mm to 10 mm. The accuracy of the LVDT is ± 1 % of the measured wear in µm, and the least count is 1 µm, which helps to measure wear from 3 µm to 1,200 µm. The heating temperature can be raised up to 400 °C. The wear track diameter varies from 55 mm to 154 mm. In the present study, it is held constant at 100 mm. a b c Fig. 2. Pin-on-disc tribometer (a) pin heater, (b) experiment setup and (c) controller and Windcom software A suitable track diameter was selected corresponding to the disk rotation to finalize sliding velocities according to the CCRD (central composite rotatable design) experiment framework. This experimental design provides consistent prediction variance at equidistant points from the center of the design space. CCRD allows the input variable levels to be determined by using an alpha value calculated using (2K)×0.25, where K is the number of input variables. In the present study, three variables (pressure, rotational speed, and temperature) were considered, which results in an alpha value of ± 1.682. Initially, the minimum and maximum range of variables was established based on actual working constraints and assigned values of −1.682 and +1.682, respectively. The intermediate levels were determined using linear interpolation and a linear equation (Alpha value = a + b × variable value). These derived intermediate levels ensure even distribution within the minimum and maximum range. Table 2 shows the levels of parameters selected for the experimentation, and Table 3 shows the alpha values and corresponding intermediate levels of the variables.
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