Papers by Keyword: Surface Integrity

Abstract: Properties of workpieces, like residual stress in the rim zone, cannot be predicted for manufacturing technologies reproducible in advance. This lack of predictability shall be solved by a new approach, called Process Signatures. These Process Signatures will combine the material loadings forced by the manufacturing process with the change of state variables, e. g. the variation of residual stress in the surface layer. As the Process Signatures shall achieve comparability for different processes with same physical working principle, it is necessary to describe the transition from material loadings to the change of material properties in a uniform way. Consequently an energy based approach is chosen that considers these transitions by the dissipation of the several kinds of energy brought into the manufacturing process and especially in the respective working area.A first step for the development of such Process Signatures is the identification of all process specific material loadings. This paper presents several material loadings generated during the electrochemical sinking process. In a further step the contribution of the individual material loadings to the material removal process are estimated. Finally first approaches for the combination of the main material loadings and the change of material properties are presented.

Abstract: Today, the study of surface integrity became a growing and multidisciplinary branch of science. Its purpose is to gain such understanding of the surface which can be exploited in real-world applications and in commercial services. The importance of the surface was and continues to be the topic of a number of highly specialized papers. However, the surface has not been yet evaluated in terms of multiple factors in order to obtain a comprehensive picture of its condition and to reveal the interrelationship between the manufacture of the surface and its resulting properties. The paper gives a description of effects of special cutting tools on the structure of the sub-surface region. These structural changes will be explored by means of metallographic observation, hardness measurement and evaluation of residual stresses.

Abstract: Sustainable manufacturing in most developed countries is one of principal goals in today manufacturing industry. The reduction in use of oil-based CLFs is most ecologically important task of machining processes. The paper presents the contribution in engineering of surfaces particularly in surface morphology of Stainless Steels. The objective of the investigation was to determine the surface texture of duplex stainless steel after turning with coated carbide tool point. The investigation included geometrical parameters of Surface Integrity for different cutting parameters in dry turning process of duplex stainless steel.

Abstract: The paper presents the contribution in engineering of surfaces particularly in surface texture of Austenitic Stainless Steels. The objective of the investigation was to determine the surface texture of austenitic stainless steel after turning with coated carbide tool point. The investigation included geometrical parameters of Surface Integrity for different technological cutting parameters in dry turning process of austenitic stainless steel. The article presents the surface roughness parameters with the roughness profiles (irregular slopes). The percentage of isotropic surfaces and Bearing Area of ​​Primary Model. Analyses were performed for variable cutting parameters. An Infinite Focus Measurement Machine (IFM) was used for the surface texture analysis. The study was performed within a production facility during the machining of electric motor parts and deep-well pumps.

Abstract: This study discussed about the influence of the cutting speed and radial depth of cut on surface integrity (microhardness and work-hardening) when performing hard milling of AISI D2 workpiece. By using PVD-TiAlN, nine experimental trials were performed at various cutting speeds of 80, 100 and 120 m/min and various radial depth of cut of 3, 4 and 5 mm as feed and depth of cut remain constant at 0.05 mm/tooth and 0.05 mm. From the result, due to high cutting temperature generated, the cutting speed adversely affects the microhardness value of the subsurface layer. At higher cutting speed of 120 m/min higher hardness values were obtained when compared with lower cutting speed of 80 m/min. As for the effect of the radial depth of cut it is clear that it influences the microhardness beneath the surface. Higher microhardness recorded from the radial depth of cut increment associated with high cutting temperature generated during machining.

Abstract: A series of grinding experiments were carried out with CBN wheel to focus on the surface integrity of titanium alloy TC4-DT in high speed grinding . In order to get the proper process parameters to control the surface integrity of the TC4-DT, surface roughness, subsurface morphology and microhardness variations have been studied. In addition to the use of CBN wheel, scanning electron microscopy (SEM), 3-d contour instrument and microhardness tester was applied. The results show that the surface roughness is decreased obviously when grinding wheel linear velocity rises from 60m/s to 80m/s. While the grinding speed rises from 80m/s to 100m/s, the surface roughness value increases slightly. Moreover, the surface roughness value increases with the grinding depth and the increasing trend is obvious in the process of machining. The microstructure analysis shows that during high speed grinding with CBN wheels, good quality surface with 10μm grinding depth can be obtained. Table feed rate has weak influence on the grinding surface topography. The microhardness analysis indicates that surface microhardness increases sharply with the increasing of grinding wheel linear velocity in high speed grinding.

Abstract: The surface residual stress and integrity of workpiece have significant effects on the precision, the reliability and the fatigue life of the mechanical products. Since the most final surface integrity of workpiece depends on the grinding process mainly in engineering, this paper analyzed the surface residual stress of ground surface through the simulation works. Based on the finite element model and the thermal mechanical coupling field of the surface grinding for 45 steel was simulated and analyzed. The distribution of the residual stress and the effects of grinding parameters on residual stress were discussed. In addition, the measures for improving the residual stress in ground surface were put forward.

Abstract: The study presents the contribution in engineering of surfaces particularly in surface morphology of Austenitic Stainless Steels. The objective of the investigation was to determine the surface morphology of austenitic stainless steel after turning with coated carbide tool point. The investigation included geometrical parameters of SI for different cutting parameters in dry turning process of austenitic stainless steel. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps.

Abstract: The grinding heat directly affected workpiece surface in the grinding process and it might produce some defects such as crack and burn. Meanwhile wear debris generated in the grinding process could easily embed grinding wheel blowhole and caused clogging and passivation. So it was particular important to avoid defects and improve the grinding workpiece surface integrity effectively. This paper established an incompressible turbulent fluid spray model based on the study of the existing airflow and the grinding fluid distribution in the grinding zone. Then according to different grinding fluid supply parameters established the two-phase gas liquid spray flow model by using CFD(computational fluid dynamics), simulated and calculated the model, compared the mass flow rate of the grinding fluid flow field with different spray distances, heights, speeds and spray angles in the grinding zone and determined the most reasonable spraying jet position. At the last, through researching on the workpiece surface integrity experiment, it provided an experimental basis to determine the most suitable spray jet position and verify the rationality of supply parameters selection.

Abstract: In order to generate desired functional properties in the surface layer of machined parts, today several iterative attempts are needed to achieve the specified surface and subsurface properties. Despite progress in simulation and modelling, which is limited to individual processes and investigations, a predictive adjustment of a manufacturing process in terms of a specific state of surface integrity is not possible. In this work, an alternative view regarding manufacturing processes, based on occurring internal physical mechanisms, is presented. It is shown for several processes, that the surface integrity due to material modifications can be correlated with internal material loads occurring during the process. To utilise this method in practical applications, approaches are presented which should enable a reduction in the complexity of the mathematical description of the internal material loading states.