Influence of the linear tip relief modification in spur gears and experimental evidence

In this paper issues about tip relief modification and its effect in terms of surface loading of the tooth flank are investigated. The linear tip relief modification is considered. This kind of modification is considered to be potentially dangerous for contact pressure which is the primary reason of micro-pitting activation. Indeed the nominal tip relief topography does not provide further continuity than only C and then gives rise to a sharp edge. In the paper an effective profile is defined on the basis of direct measurements and more realistic contact pressure at start relief profile modification is determined. Numerical results are compared to experimental evidence.