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Residual stresses in the surface layer exert a significant impact on functional aspects of machined parts. Their type and value depend on the workpiece and tool material properties, cutting parameters and cooling and lubrication conditions in the tool-chip-machined surface interface. As the effects of material properties and cutting parameters have been widely studied, the influence of cooling and lubrication conditions, especially minimum quantity lubrication (MQL) on the surface layer residual stresses and the relationships between them have not been investigated. In this paper the effects of dry, MQL cutting and cutting with emulsion conditions together with cutting parameters on residual stresses after turning AISI 316L steel were investigated. X-ray diffraction method was used for measuring superficial residual stresses in the cutting (hoop) and feed (axial) directions. Tensile residual stresses were detected in both directions and the values in the cutting direction turned out to be higher than in the feed direction. The effects of cooling and lubrication conditions largely depend on the selected cutting parameters, whose influence is linked to the cutting zone cooling and lubrication mode. Elaborated regression functions allow calculation and optimization of residual stresses in turning AISI 316L steel, depending on cooling and lubrication conditions as well as cutting parameters.

The mode of application of cutting liquids in cutting processes determines the properties of the produced surface, workpiece dimensional accuracy, and tool wear, as well as the physical phenomena which occur during cutting. However, their application causes many ecological and social problems connected with environmental pollution and operator health. Their elimination or significant reduction demands a comparable machined surface quality in dry cutting conditions or with a minimized quantity of lubricant. The current paper presents results of research into the cutting process, describing the topographical surface properties obtained in dry and with minimum quantity lubrication (MQL) turning of AISI 316L steel, which have been compared with those obtained after a conventional supply of emulsion. Previous investigations performed on the impact of cutting environment on machined surface quality were usually made in dry or wet conditions. The surface texture was analysed on the basis of the surface roughness parameter Ra, neglecting other important surface features. For this reason surface hybrid roughness profile parameters and the Abbott-Firestone curve as well as the surface topography have been used in the present paper. The experimental results showed a considerable influence of the cutting zone environment and parameters on the cutting force, surface roughness, profile bearing ratio, and the occurrence of surface defects. The presented regression functions allow a calculation and prediction of surface roughness values as a function of cutting zone cooling and lubrication conditions and selected values of cutting parameters in the turning of AISI 316L steel.

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W artykule zaprezentowano wyniki badań, wraz z ich analizą, wpływu warunków wiercenia w materiale kompozytowym włók-nistym, stosowanym do budowy czołownic pojazdów szynowych, na wartość współczynnika delaminacji. SŁOWA KLUCZOWE: delaminacja kompozytów, materiały kompozytowe włókniste, wiercenie w kompozytachThe original research results and their analysis of delamination phenomena during drilling in fiber composite material, used to build headstocks rail vehicles were presented and discussed in this article.