Papers by Keyword: Roller Burnishing

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Authors: A.A. Ibrahim
Abstract: Roller burnishing process was applied to Al2O3/A356 composite specimens. The process was carried out on vertical milling machine. Effects of the burnishing process with varying process parameters on the characteristics of the machined surface and sub-surfaces were investigated. Residual stress distribution at different depths beneath the burnished surfaces, microhardness distribution, surface roughness were used as criteria to obtain the optimum burnishing conditions that give burnished surfaces with high integrity for the Al2O3/A356 composite. Results showed an improvement in surface characteristics of Al2O3/A356 composites using burnishing process. The better surface roughness was obtained with double passes burnishing, depth of penetration of 0.12 mm, and burnishing speed of 72 mm/min. Increase of number of burnishing passes increases the value of residual compressive stress and the microhardness at the burnished surface and subsurface. The microhardness slightly decreased with the increase of burnishing speed.
Authors: Werner Menk, Sabine Tunzini, Torsten Rieck, Christoph Honsel, Konrad Weiss
Abstract: A lot of innovations in molding and casting technology and also simulation techniques have made ductile iron more and more competitive and it even competes meanwhile against steel forgings. A successful substitution of steel forgings for example is the wheel carrier for a high volume car with the Georg Fischer new ductile iron material 'SiboDur', a ductile iron family with high strength and high elongation at the same time. But there is still a great potential for ductile iron castings to substitute steel forgings, in particular in the automotive industry. One example is the crankshaft for the engine: Quite a lot of gasoline engines are equipped with ductile iron crankshafts, but for instance most of the diesel engines are still running with forged steel cranks. The reason is mostly the belief of design engineers that it is not possible to get similar fatigue limit with castings com-pared to forged steel. This belief may often be correct, but using local strengthening technologies, such as roller burnishing of bearing fillets or inductive hardening of highly stressed areas can raise the fatigue limit of casted crankshafts dramatically. The paper presents studies which show that using the right ductile iron material and optimized roller burnishing conditions can raise the fatigue limit of cast crankshafts to values even higher than forged steel ones (material 38MnVS6). But even quenched and tempered forged steel crankshafts are in the focus to be substituted by castings. It is well known that ductile iron also can be induction hardened, but the induction hardening of ductile iron is still an empirical technology. This leads to the second part of the paper: In a cooperation of Georg Fischer and RWP a research project was carried out to develop a simulation technology to predict the residual stresses in a cast crankshaft due to induction hardening under different condi-tions. The results are very encouraging and enable us today to predetermine the induction hardening conditions to get optimized fatigue behavior of ductile iron crankshafts. Of course, the findings can also be used for other applications than crankshafts.
Authors: Yuki Nakamura, Masaki Nakajima, Hiroaki Masuda, Toshifumi Kakiuchi, Yoshihiko Uematsu
Abstract: Roller burnishing (RB) and friction stir processing (FSP) were applied to a cast aluminum alloy, AC4CH-T6 (equivalent to A356-T6), to improve the fatigue properties. In roller burnished specimens, Vickers hardness was increased until the depth of 60μm compared with that of the as-cast specimens, resulting in work-hardening by RB. The compressive residual stress on the surface of the roller burnished specimens was also increased from 35MPa to 132MPa. In order to investigate the effect of RB on the fatigue properties, rotary bending fatigue tests have been performed using the roller burnished and the as-cast specimens. The roller burnished specimens exhibited higher fatigue strength than the untreated specimens. It is due to the increase in hardness and compressive residual stress by RB. In addition, plane bending fatigue tests have been performed using the friction stir processed and untreated specimens. Fatigue strengths of the friction stir processed specimens were highly improved compared with untreated specimens as the results of the elimination of casting defects by FSP. However, the crack growth rates of the friction stir processed specimens were faster than those of untreated specimens. It is due to the softening of the material by heat input during the FSP.
Authors: Masato Okada, Takuma Hirokawa, Naoki Asakawa, Masaaki Otsu
Abstract: The influence of burnishing conditions on the burnishing force in the inclined roller burnishing method, which was developed by the authors, is investigated. The wear behaviors of non-coated and TiN- and Diamond-Like-Carbon-coated rollers and the effect of the coated roller on the inclined roller burnishing were also investigated. A round bar of carbon steel and an aluminum-based alloy were used as the workpiece material. The burnishing force was measured by a strain-gauge type 3-component dynamometer. The burnishing force component, which acts in the circumferential direction of the workpiece, increased with increasing inclination angle of the roller. Improvement of the tool life of the roller was obtained with a TiN-coated roller on which nitriding treatment of the base roller was performed prior to TiN coating. A satisfactory burnished surface was obtained by burnishing with the DLC-coated roller.
Authors: Janny Lindemann, Anja Kutzsche, Michael Oehring, Fritz Appel
Abstract: The effect of shot peening and roller burnishing on the fatigue performance of the γ(TiAl) alloy Ti-45Al-9Nb-0.2C was investigated over a wide range of processing intensities. At optimized conditions shot peening and roller burnishing can markedly improve the fatigue strength at ambient temperatures. For temperatures above 650 °C, the residual compressive stresses induced by shot peening and roller burnishing quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become more important for the fatigue performance of mechanically surface-treated components. Roller burnishing leads to much lower surface roughness than shot peening, resulting in more effective improvement of high temperature fatigue performance. However, surface strengthening by shot peening can also be beneficial for the fatigue performance at elevated temperatures, when the surface roughness is reduced by subsequent polishing.
Authors: Feng Lei Li, Wei Xia, Zhao Yao Zhou, Tian Zhang
Abstract: Burnishing, an ultra-precision superficial plastic deformation process, is used increasingly as a surface enhancement finishing treatment after machining operations not only to give a mirror-like and work-hardened surface but also to impose favorable compressive residual stress in it. To analyze the feasibility of turning-burnishing hybrid process, the Taguchi’s L27(313) orthogonal array method with the analysis of variance (ANOVA) were used to analyze the influence of the initial turning process on surface integrity of roller burnished AISI 1045 steel such as surface roughness, surface microhardness. three turning parameters, namely the cutting feed, cutting depth and cutting speed, three burnishing parameters, namely the burnishing feed, burnishing depth and burnishing speed were selected as the experimental factors in Taguchi’s design of experiments to determine which one has the dominant influence and how it works on burnishing effects, namely the surface roughness and surface microhardness, the interactions between cutting feed, burnishing feed and burnishing depth were considered. The experimental results agreed well with the theoretical analysis and the conclusion is cutting feed has dominant influence on burnished surface integrity.
Authors: Masato Okada, Yuki Miyagoshi, Masaaki Otsu
Abstract: This paper proposes a roller burnishing method that controls the sliding direction of the burnishing tool on the surface of cylindrical workpiece. In this study, the sliding direction was set by inclining the axis of the burnishing tool with respect to the axis of the workpiece and by actively rotating the roller of the burnishing tool. The workpiece was a cylindrical aluminum alloy bar, which was rotated in a bench lathe. The burnished surfaces at several sliding angles between 15º and 90º were evaluated. The sliding direction, which is set according to a theoretical equation, was experimentally obtained for every sliding angle in the range of 15-90º with respect to the circumferential direction of the workpiece. The sectional profile was flattened and surface roughness was decreased with increasing sliding angle. As a result, the burnished surfaces obtained in this work were superior to those obtained in an earlier study by the authors, in which the burnishing tool was not actively rotated.
Authors: Janny Lindemann, Maria Glavatskikh, Christoph Leyens
Abstract: Surface conditions are of significant importance for the fatigue performance of rotating components for aircraft and automotive applications. Compared to the electropolished reference state the fatigue performance of gamma titanium aluminides at ambient temperature can be significantly improved by shot peening, while the fatigue strength after roller burnishing is hardly affected. Fatigue strength improvements after shot peening are mainly caused by cyclically stable residual compressive stresses in the near-surface region. Notably, also conventional turning operations generate high dislocation densities and residual compressive stresses in the near-surface region resulting in fatigue strength improvements similar to shot peening. Surface strengthening by shot peening or machining leads to subsurface fatigue crack nucleation and overcompensates the detrimental influence of the high surface roughness on fatigue. However, for temperatures above 650 °C, residual compressive stresses induced by shot peening and machining quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become increasingly important for the fatigue performance of components.
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