Correlation between surface topography and lubricant migration in steel sheets for the autobody manufacturing process

Abstract

Material for the production of autobody panels is usually dispatched in the form of coils. Because of their weight, they tend to `compress' the lubricant applied for rust protection and some of it leaks from the coil. Those areas affected by lubricant starvation are known as `dry-spots' and are a cause of a number of product rejections during the subsequent forming operation. A test was deployed with the combined work of Ocas, CORUS IJmuiden and Renault that proved that surface topography controls, amongst other factors, affects lubricant migration. The test consists of compressing a stack of lubricated steel sheets at known pressure for a known time using different lubricants in different amounts. It was observed that, because of the `compression', the lubricant tends to migrate to the side of the sheet, and its migration was quantified using a Fischer Betascope MMS module. Analysis consisted of analysis of variance on several designs of experiments and subsequent correlation with surface topography 3D parameters. These experiments showed the importance of standard amplitude surface parameters and new closed area surface parameters to characterize lubricant migration under pressure.

Physical Modeling of the Steel Sheet Topography in Skin Pass Rolling and Its Influence on Susceptibility of Sheets to Deep Drawing

“…One of the aims of skin passing is to ensure suitable surface topography of steel sheets that should facilitate further processing of sheets and should provide the best surface quality of formed parts . This task is carried out with the use of skin pass mill with work rolls of properly prepared surface topography.…”