Development of tribolojical properties of a diesel fuel pump cam follower

System pressure in fuel injection system are required to be increased due to the fact that diesel engines are obligated to follow tighten emission standards. This means increase of hydraulic forces on the components that are subjected to pressure in fuel injection system. The increase of hydraulic forces on especially moving components that has friction surfaces, causes tribological problems. One of these problems is encountered in cam follower mechanism of a fuel pump which produces the pressure in fuel injection system. The reason of the problem is considered as fatigue and adhesion wear based on metal to metal contact according to the microscope investigations. Therefore, some alternative coatings for the solution of the problem are investigated within the content of this thesis. The coatings are, thin film coatings; TiN, CrN and three different DLC forms; and MoS2 and PTFE coatings. Tests are performed in a test bench designed and produced within the content of this study. All coatings are tested under the same test conditions and assessed according to the test results as friction coefficient, component temperatures at high speeds, surface roughness change of wear region, wear depth and wear mechanism. According to all the assessments, TiN and CrN coatings are found better compared to the others. Additionally, the results from MoS2 coating are considered as positive but it seems necessary to investigate operation life of the coating. As a result, the outcome of this thesis, TiN and CrN coatings have better potential as the solution of the problem and TiN and CrN coatings can be applied to the real components in order to test their real performance on real test conditions.