Skf Sverige Ab

Gothenburg, Sweden

Skf Sverige Ab

Gothenburg, Sweden
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Lofgren B.,Skf Sverige Ab | Tillman A.-M.,Chalmers University of Technology | Rinde B.,Skf Sverige Ab
Journal of Cleaner Production | Year: 2011

Modern industrial environmental management encompasses life-cycle thinking. This entails considering not only the emissions and resource use of the company's production processes, but also the environmental consequences of all processes related to a product's life cycle. However, no single actor can influence the whole life cycle of a product. To be effective, analysis methods intended to support improvement actions should therefore also consider the decision makers' power to influence. Regarding the life cycle of a product, there are at least as many perspectives on life-cycle thinking as there are actors. This paper presents an approach with which manufacturing decision makers can sharpen the focus in life-cycle assessment (LCA) from a conventional 'products or services' emphasis to a company's manufacturing processes. The method has been developed by combining knowledge gained from earlier LCA studies with new empirical findings from an LCA study of an SKF manufacturing line. We demonstrate how system boundaries and functional units in an LCA can be defined when adding the perspective of a manufacturing decision maker to the product life-cycle perspective. Such analysis helps manufacturing decision makers identify improvement potentials in their spheres of influence, by focusing on the environmental consequences of energy and material losses in manufacturing rather than merely accounting for the contributions of individual stages of the life cycle to the overall environmental impact. The method identifies and directly relates the environmental consequences of emissions or raw material inputs in the product life cycle to manufacturing processes. In doing so, the holistic systems perspective in LCA is somewhat diminished in favor of the relevance of results to manufacturing decision makers. © 2011 Elsevier Ltd. All rights reserved.


Lofgren B.,Skf Sverige Ab | Tillman A.-M.,Chalmers University of Technology
Journal of Cleaner Production | Year: 2011

To meet the increasing need for practical life-cycle thinking in manufacturing, this paper proposes a method that includes the life-cycle perspective in manufacturing decision making. This method combines discrete-event simulation (DES) - commonly used for the conceptual evaluation of manufacturing systems - with life-cycle assessment (LCA). This combination captures the dynamic interrelationships between manufacturing processes in order to analyse systemic responses to configuration changes, something static LCA modelling cannot do. The method evolved when a bearing production line at SKF was being examined to relate manufacturing decision making to environmental consequences. This was done using DES to investigate how parameters normally used to optimize traditional manufacturing system performance influence energy use and material losses in manufacturing systems. The environmental consequences of this material loss and energy use are further calculated using LCA methodology. Results indicate that while the combination of the two methods increases the data collection workload, it uncovers previously hidden environmental consequences of manufacturing decision making and introduces a way to assess an industrial actor's manufacturing system using relevant LCA scenarios. © 2011 Elsevier Ltd. All rights reserved.


Sherif M.Y.,SKF Corporation | Han B.,SKF Corporation | Kahlman L.,Skf Sverige Ab
ASTM Special Technical Publication | Year: 2012

The current paper presents the results obtained from testing of high-nitrogen martensitic stainless steels and a cobalt-based alloy using an accelerated railing contact fatigue tester, the Polymet test rig. Although demineralised water is not a good lubricant in terms of, for example, its capability of building up a sufficient film thickness, it was possible to rank the tested alloys according to their performance. Corrosion products were observed on the over-rolled tracks, and the materials' resistance to pitting corrosion was assessed. Copyright © 2012 by ASTM International.


Gabelli A.,SKF Corporation | Lai J.,SKF Corporation | Lund T.,Skf Sverige Ab | Ryden K.,Skf Sverige Ab | And 3 more authors.
International Journal of Fatigue | Year: 2012

The dynamic load ratings and life rating standard for rolling bearings, ISO 281:2007, makes use of a fatigue limit stress of hardened bearing steels as a parameter in the estimation of the fatigue life of rolling bearings. Part I of this paper series presented an analytical-probabilistic model that provides a unified prediction of fatigue strength corresponding to various fatigue regimes including the very high cycle fatigue (VHCF) regime. Based on the fatigue model, Monte Carlo simulation of rotating bending and push-pull tests of bearing steels indicates the existence of a horizontal asymptote in the S-N curve in excess of 10 12 cycles, which corresponds to the fatigue limit. Prediction of fatigue limit associated with certain reliability can be realized using the developed model and methodology. In the present paper (Part II of the paper series), the application of a fatigue limit stress in the standard fatigue load ratings of rolling bearings is described. The up-to-date interpretations and standard definition of the fatigue limit stress are discussed in relation to the very long stress cycling. The recent developments and results in the area of VHCF testing of hardened AISI 52100, SUJ2, 100Cr6 bearing steels are also reviewed. The fatigue limits predicted using the model from Part I, are compared with the VHCF data of bearing steels available from both the in-house tests and those in the literature. Good correlation is observed between the fatigue limit model and the experimental results. Plotting the experimental data on top of the predicted fatigue limit shows that the S-N data approaches asymptotically the predicted fatigue limit in the VHCF regime. It is found that the predicted fatigue limits and the VHCF testing data correlate well with the fatigue limit value set in the ISO 281:2007 standard for life rating of rolling bearings. © 2011 Elsevier Ltd. All rights reserved.


Lai J.,SKF Corporation | Lund T.,Skf Sverige Ab | Ryden K.,Skf Sverige Ab | Gabelli A.,SKF Corporation | Strandell I.,Skf Sverige Ab
International Journal of Fatigue | Year: 2012

Bearing steels and other high strength steels exhibit complex fatigue behavior in excess of 10 7 cycles due to their sensitivity to defects like inclusions. Failure occurring in the very high cycle fatigue regime and the lack of an asymptote in the measured S-N data raise the questions as to the existence of fatigue limit and prediction of the fatigue strength of the high strength steel components. A series of two papers are written to discuss on the characteristics of the very high cycle fatigue and their implication for engineering applications. In the present paper (Part I) a deterministic defect model is developed to describe the fatigue crack growth from de-bonded hard inclusions. The model is shown to provide a unified prediction of fatigue behavior in different regimes, i.e. low cycle fatigue regime dictated by the tensile strength, high cycle fatigue regime obeying Basquin's law and the very high cycle fatigue regime featured by the fish-eye and ODA (optically dark area) surrounding an interior fatigue-initiating inclusion on the fracture surface. The model predictions agree well with experiments. A combination of the deterministic model with a stochastic model that describes the inclusion size distribution allows prediction of fatigue strength and fatigue limit associated with certain reliability of a steel component. It is found that very high cycle fatigue, associated with interior inclusions, is attributed to the very slow crack propagation in vacuum condition, and that an asymptote for fatigue limit observed for mild steels also exists for high strength steels such as bearing steels, but extends beyond the very high cycle fatigue regime normally measured to-date. Monte Carlo simulation shows that such a fatigue limit asymptote becomes clearly visible in excess of 10 12 cycles, which is difficult to measure with today's testing devices. Furthermore, the effects of steel cleanliness and specimen type and shape are studied by means of Monte Carlo simulations. © 2011 Elsevier Ltd. All rights reserved.


Ryttberg K.,Chalmers University of Technology | Knutson Wedel M.,Chalmers University of Technology | Recina V.,Skf Sverige Ab | Dahlman P.,Skf Sverige Ab | Nyborg L.,Chalmers University of Technology
Materials Science and Engineering A | Year: 2010

This paper concerns the development of microstructure and texture during cold ring rolling of 100Cr6 steel rings with starting rectangular cross-sections. By interrupting the rolling process at pre-defined intervals expansion ratios ranging from 1.05 to 1.5 were achieved resulting in varying degrees of deformation of the rings. Results for rings with a simple rectangular cross-section were compared with results for a cold rolled ring with a more complex cross-section. By combining results from optical and scanning electron microscopy with hardness measurements the two different ring shapes were shown to display similar material flow during cold ring rolling. The deformation was most severe near the inner diameter of the rings decreasing towards the area of the outer diameter. By employing electron back scatter diffraction (EBSD) the ring rolling process was shown to change the {1 1 1}-fibre texture of the ring blanks to a {1 1 0} texture. This implies a mixture of both shear and compressive deformation during rolling. © 2009 Elsevier B.V. All rights reserved.

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