Auswirkung der Schneidkanteneigenspannungen auf das Verschleißverhalten PVD-beschichteter Zerspanwerkzeuge

To increase the tool life, tools are coated with hard material layers. One of the most important coatings for universal use is the (Al,Ti)N-PVD coating. Residual stresses are one of the most important properties for the quality, operating behaviour and tool life. It is generally known that residual compressive stresses have a positive effect on the fatigue life of a component subject to alternating loads, as they counteract crack formation and propagation. Residual tensile stresses, on the other hand, shorten the fatigue life because they promote the formation and propagation of cracks.

However, the known direct measurement methods for residual stress measurement cannot be applied to the cutting edge, as the cutting edge provides a very small measurement range. Raman spectroscopy offers potential for the measurement of residual stresses in optically transparent materials. The sample to be investigated is irradiated with monochromatic light and the incoherently scattered light is analysed. With a laser as a light source, very high intensities and a strong localization of the measurement in micrometre scale can be achieved. Raman spectroscopy is calibrated on flat samples using the X-ray in the scattering vector mode. The residual stresses in the cutting edge of inserts are measured and the tool life is determined by field tests. By comparing the measured residual stresses and wear behaviour, the influence of the residual stress state on the tool life can be determined and an empirical model established.