Strategic surface topographies for enhanced lubrication in sheet forming of stainless steel

Strategic stainless steel surfaces have been developed for which the tribological properties are significantly improved for sheet-metal forming compared with the as-received surfaces. The improvements have been achieved by modification of the surface to promote Micro-Plasto Hydrodynamic Lubrication (MPHL) by increasing the ratio of closed lubricant pockets and modifying the pocket geometry. These factors influence the retention and subsequent escape of lubricant during forming thus enhancing lubricant permeability to the contact between flattened workpiece asperities and contacting tool. The technique, which has been developed, is based on an electrochemical treatment changing the topography of the stainless steel surface. Comparative testing of the new surface topographies in ironing and deep drawing of stainless steel sheet shows significant improvements and possibilities of replacing chlorinated paraffin oils with environmentally friendly plain mineral oil.

[1]  H. Kudo,et al.  An Interpretation of the Speed Dependence of the Coefficient of Friction under the Micro-PHL Condition in Sheet Drawing , 1991 .

[2]  Jan Lasson Andreasen,et al.  Major process parameters affecting limits of lubrication in deep drawing of stainless steel , 1997 .

[3]  Hajime Takada,et al.  An Investigation into Plasto-Hydrodynamic Lubrication with a Cold Sheet Drawing Test , 1982 .

[4]  N. Bay,et al.  A Study of Mechanisms of Liquid Lubrication in Metal Forming , 1998 .

[5]  Jan Lasson Andreasen,et al.  A strip reduction test for measurement of lubricity in ironing , 1996 .

[6]  T. Mizuno,et al.  Effects of Lubricant Viscosity at Pressure and Sliding Velocity on Lubricating Conditions in the Compression-Friction Test on Sheet Metals , 1982 .

[7]  Niels Bay,et al.  Entrapment and escape of liquid lubricant in metal forming , 1999 .

[8]  Jan Lasson Andreasen,et al.  A Basic Study of the Influence of Surface Topography on Mechanisms of Liquid Lubrication in Metal Forming , 1998 .

[9]  Manfred Geiger,et al.  New Developments for the Qualification of Technical Surfaces in Forming Processes , 1997 .

[10]  H. Kudo,et al.  Direct Observation of Contact Behaviour to Interpret the Pressure Dependence of the Coefficient of Friction in Sheet Metal Forming , 1995 .

[11]  Dieter Schmoeckel,et al.  Topography Deformation of Sheet Metal during the Forming Process and Its Influence on Friction , 1997 .

[12]  Mpf Sutcliffe,et al.  Characterisation of pit geometry in cold-rolled stainless steel strip , 2002 .