Tribological interferences on the cylinder head union associated with the seal and its effects on the bolted joint tightening process

The automotive industry has a lack of knowledge when the subject comes to screw joint technique, especially regarding tribological interferences. These themes are not commonly explored together on studies to comprehend the behavior between contacting surfaces. When there is a specific goal, as the one proposed in this paper: to ensure all control levels to eliminate sealing deficiency risks inside combustion chamber in a low investment cost, these needs are even higher. The tribological analysis between diesel engine block and its cylinder head is essential to understand the minimum requirements to achieve the best possible sealing, mostly when it comes to assembly tightening process routines. In this sense, this work puts forward a methodology to set best tightening conditions in order to guarantee the sealing to whatever surface topography. Additionally, the acquired knowledge can be used to other similar applications associated to bolted joints, such as in other vehicle parts. Even though in other circumstances, when the critical screw joint goal focus is not on sealing efficiency, but for example on extremely high fatigue conditions exposed to external work, the method developed on this work presents a good path to achieve better clamping loads. Also, in many manufacturing processes the surface topographies may range according to the machining parameters, which are defined not considering the effects of tightening and consequently on the clamping results stability. Based on that, this study takes into account this negligence and guides to a tightening specification that increases stability on clamping load losses.