Increased use of forging tools in mass production causes their increased wear and creates pressure to design more efficient renovation process. Renovation is complicated because of the identification of cracks expanding from the surface to the core material. Given that the production of forging tools is expensive, caused by the cost of tool steels and the thermo-chemical treatment, it is important to design forging tool with its easy renovation in mind. It is important to choose the right renovation technology, which will be able to restore the instrument to its original state while maintaining financial rentability. Choosing the right technology is difficult because of nitrided and heat-treated surface for high hardness and wear resistance. Article discusses the use of non-destructive method of detecting cracks taking into account the size of the cracks formed during working process.

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Residual stresses significantly affect the life of parts material, especially in bearing manufacturing, where the stress introduced into the material in the manufacturing process affect the component throughout its whole operating life. It is therefore important to know the size and orientation of these stresses and to optimize the production process of the bearing rings, in order to eliminate as many of these undesirable stresses. The subject of the article is chosen at demand of practice and has to correlate coating cutting tool for residual stress and microstructure in turning the outer bearing rings made of material 1.3520, which is widely used in bearing production. Turning cutting tool WNMG 080408E-M was used with two different coatings. We conducted measurements on a X-ray diffractometer. We measured normal stress parameter and the FWHM (full width half maximum at), which is decisive, and it is related to the grain size of the material. We found that the residual axial stress approaching the zero value, depending on the etched layer.

This paper is focused on analysis of residual stress of functional surfaces and subsurface layers created by precision technologies of hard machining for progressive constructional materials of forging tools. Methods of experiments are oriented on monitoring of residual stress in surface which is created by hard turning (roughing and finishing operations). Subsequently these surfaces were etched in thin layers by electro-chemical polishing. The residual stress was monitored in each etched layer. The measuring was executed by portable X-ray diffractometer for detection of residual stress and structural phases. The results significantly indicate rise and distribution of residual stress in surface and subsurface layers and their impact on functional properties of surface integrity.

Experiment includes the study and identification of monolithic ceramic mining tools by machining the Domex 700 steel that belongs to the group of tough metals with high tensile strength. During the process of machining, the substandard high cutting speeds were used. Identification of ceramic mining tools included the analysis of cutting edge wear and the construction of map of surface roughness parameter Rz dependence on the change of cutting conditions for a given range (machine and material).