Influence of Dry Film Lubricant on Press Formability of Steel Sheets

We have developed a new dry film lubricant with friction properties superior to those of conventional dry film lubricants by optimizing the glass transition temperature of the binder resin and adding polyethylene wax and inorganic lubricants. As described in this paper, the new dry film lubricant was applied as a coating on hot rolled steel sheets and galvannealed steel sheets in thicknesses ranging from 1.5 to 2.5 μm. The influence of the dry film lubricant and a rust preventive lubricant oil on the press formability of these steel sheets was investigated. A comparison of the press formability of high strength steel sheets with the dry film lubricant and sheets with the rust preventive lubricating oil suggested that application of the new dry film lubricant expands the use of high strength steel sheets and galvannealed steel sheets in automotive body panels. Furthermore, these steel sheets with the dry film lubricant showed the same alkaline degreasability, phosphatability and spot weldability as steel sheets with rust preventive lubricating oil. These results suggested also that steel sheets with the dry film lubricant can be used widely in automotive body panels.