Tribology of Stamping; The Influence of Designed Steel Sheet Surface Topography on Friction
Doktorsavhandling, 2006

Tribology is the science of friction, wear, and lubrication; the interaction of surfaces in relative motion. The tribological conditions in sheet metal forming influences the flow of material in forming operations, the strain distributions of sheet material, extent of wear, and thereby the quality of products. The purpose of the thesis is to increase the knowledge of why and how sheet surface topography influence the frictional response in stamping, to characterise the geometrical properties, and make results applicable for industry. The frictional response of different surface topographies have been measured in a Bending Under Tension test under mixed lubricated conditions. The studied materials have been stainless steel sheets and uncoated and coated carbon steel sheets. The results did show the influence of roughness, skewness, and anisotropy of surface topography. The findings could be explained by the theory of pad bearings. A new functional 3D parameter (Sq>0) was developed for pressing performance that is sensitive to the effects of roughness and skewness. The texture-aspect ratio parameter (Str) was found to be correlated to the anisotropical behaviour of the frictional response. The results are very tangible and mean increased control of stamping operations. An initial step was taken to introduce more advanced tribological models in FE simulation of sheet metal forming operations. The aim is to decrease the trial-and-error time in the design process of dies and tools. A friction model considering surface topography (Sq>0), sliding velocity, lubricant viscosity, and apparent pressure, was successfully implemented. Simulations of a part were evaluated with real stamping try-outs. The results did show the potential of improving the precision in forming simulations with more advanced tribological models. Finally, theory and characterisation methods of active micro-oil pockets in the contact zone of tool and sheet were investigated. The real contact area was shown to be the critical feature to determine. Therefore, two topographical methods and one microscope-imaging processing technique were studied, but no method was found to be viable. However, the experimental results did not confirm the importance of micro-oil pockets in mixed lubricated regime.

10.00 KB-salen, Kemigården 4
Opponent: Professor, Hassan Zahouani, Ecole Centrale de Lyon, France


Daniel Wiklund

Chalmers, Material- och tillverkningsteknik, Tillverkningsteknik

Frictional Mechanisms in Mixed Lubricated Regime in Steel Sheet Metal Forming

10th International Conference on Metrology and Properties of Engineering Surfaces, Saint-Étienne, France, 4-7 July 2005,; (2005)

Paper i proceeding

The Influence of Lubricants Kinematic Viscosity and Steel Sheet Surface-Topography in a Bending Under Tension Friction Test

Proceedings of The 2nd World Tribology Congress, Vienna, Austria, 3-7 September 2001,; (2001)

Paper i proceeding

Evaluation of surface topography parameters for friction prediction in stamping

Wear,; Vol. 257(2004)p. 1296-1300

Artikel i vetenskaplig tidskrift

Surface Indentation Test (SIT) for Friction Prediction in Mixed Lubrication of Coated Sheets

Proceedings of The 28th Leeds-Lyon Symposium on Tribology, Vienna, Austria, 3-7 September 2001,; (2001)

Paper i proceeding

Frictional properties of different austenitic stainless steel sheet surface topographies: Industrial trials at Alfa Laval

IDDRG 2006 Conference, Porto, Portugal, 19-21 June,; (2006)

Paper i proceeding

A Comparative Surface Topography Study of FEM Simulation and Surface Indentation Tests (SIT) on Friction Prediction in Steel Sheet Forming

Proceedings of The 10th Nordic Symposium on Tribology, Stockholm, Sweden, 9-12 June 2002,; (2002)

Paper i proceeding

On the Implementation and Evaluation of a Roughness Based Friction Model in FE simulations of Sheet Metal Forming

Proceedings of The 12th Nordic Symposium on Tribology, Helsingör, Denmark, 7-9 June 2006,; (2006)

Paper i proceeding


Bearbetnings-, yt- och fogningsteknik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 2526

10.00 KB-salen, Kemigården 4

Opponent: Professor, Hassan Zahouani, Ecole Centrale de Lyon, France