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Characteristics of surface integrity generated by oblique machining of steel parts

Grzesik W.

Advances in Manufacturing Science and Technology

2012

Vol. 36, nr 3

5-18

In this study the surface integrity produced by oblique turning of a C45 carbon steel was quantified by means of 2D and 3D surface roughness parameters, strain-hardening effects and associated residual stresses. Surfaces were produced by a special straight-edged cutting tool with large inclination angle of 55 degrees equipped with carbide cutting tool inserts. It was documented that oblique machining performed with relatively higher feed rate allows to obtain lower surface roughness and, in general, better bearing characteristics. Moreover, compressive stresses with the maximum value located close to the machined surface and with parabolic profile can be induced into the surface layer. The magnitude of stresses depends on the strain-hardening rate of the surface layer.

W pracy scharakteryzowano stan technologicznej warstwy wierzchniej wytworzonej w ukośnym toczeniu stali C45. Stosowano kryteria parametrów chropowatości powierzchni 2D i 3D, efektu umocnienia odkształceniowego i naprężeń własnych. Powierzchnie kształtowano specjalnym narzędziem z węglików spiekanych, w którym prostoliniowa krawędź skrawająca ma duży kąt pochylenia 55 stopni. Analiza wyników badań pozwala stwierdzić, że ukośne skrawanie prowadzone z dużą wartością posuwu pozwala uzyskać powierzchnię o mniejszej chropowatości i lepszej nośności. Dodatkowo w warstwie wierzchniej są wytworzone ściskające naprężenia własne o maksymalnej wartości w pobliżu powierzchni i profilu parabolicznym. Wartość maksymalna naprężeń ściskających zależy od stopnia umocnienia odkształceniowego materiału warstwy wierzchniej.

Investigations of surface textures produced by oblique machining of different workpiece materials

Grzesik W., Żak K.

Archives of Materials Science and Engineering

2011

Vol. 52, nr 1

46-53

Purpose: The intention of this research is to test the applicability of oblique cutting tools for improving surface textures produced in turning operations on parts made of popular steels (carbon, low- and high-alloy) with different chemical compositions and microstructures as well as P-F ductile iron. The aim of the research is to quantify the surface roughness and lays produced under practical working conditions. Design/methodology/approach: The objectives were achieved by the characterization of machined surfaces using 2D and 3D scanning techniques and typical LOM examinations. The surface profile and surface topographies were characterized and compared for optimal machining conditions. Findings: This investigation confirms that oblique machining allows producing surfaces with lower surface roughness and, in some cases, with attractive service properties. The main conclusion is that oblique cutting operations can reduce machining times and partly eliminate grinding operations, especially in the machining of hardened materials. Research limitations/implications: The basic limitations concern the measurement of residual stresses and microstructural alterations. Another important problem is to optimize the surface integrity including surface roughness and sublayer properties. Practical implications: One practical outcome is selecting the machining conditions which guarantee the demanded surface finish together with bearing properties. In particular, surfaces with characteristic plateau can be produced instead of special abrasive finishing operations. Originality/value: Original value of the paper is the presentation of new cutting tools and their effects in turning operations. Experiments were performed under the conditions combining low surface roughness with attractive service properties. This knowledge can support the design of technological processes of steel and NDI parts.