During the wear time, due to the speed of surfaces, the two levels of friction coefficient and the roughness of the surface of the wearing parts are constantly changing to remain intact. Therefore, the operating conditions of the parts during wear will play an important role on the performance of contacting parts, such as gears, bearings, pins, cam, and so on. This project has two distinct phases. In the first phase, a series of experiments was performed using a pin-on-disk device on ST37 specimen in the presence of lubricant. The input parameters of these experiments are speed, force, and surface roughness and the wear volume and friction coefficient are measured. The results show that by increasing the applied load for 2-folds, the weight loss is increased by 54% and the friction coefficient slightly decreases. A model was developed to predict the friction coefficient in the point and line contacts for the lubricated case. The outcome of this model was used in a different model which was developed to evaluate the wear coefficient based on the continuum damage mechanics.There was an acceptable agreement between the predicted wear coefficient and the experimentally-obtained values. Key words: Wear, Pin-on-disk, Damage Mechanics, Point Contact, Line Contact, Mixed-Lubrication
