Application of an Oleophobic Coating to Improve Formability in the Deep-Drawing Process

Abstract

The competition among sheet-metal-forming manufacturers in recent years has become more severe. Many manufacturers have survived by cutting their production costs. Increasing the formability, which could reduce the production costs, is the focus of many manufacturers and engineers. In the present research, to increase the formability over the limiting drawing ratio (LDR) in the cylindrical deep-drawing process, the application of oleophobic coating is proposed. An SUS304 (JIS standard)-stainless-steel cylindrical deep-drawn component was used as the investigated model. First, we applied the oleophobic coating in the sheet-metal-forming process, and tribology tests were carried out to examine the friction coefficients, which were reduced by approximately 60% compared with those of standard lubricant use (Iloform TDN81). Next, deep-drawing tests were performed to investigate the drawing ratio (DR). The LDR recommended in the past could be overcome, and it increased by approximately 12% with the oleophobic coating use. Finally, the deep-drawing mechanism using an extremely low friction coefficient was clarified as well. Based on these results, an oleophobic coating could be applied in the cylindrical deep-drawing process to increase the LDR. The results also clearly expose the multidisciplinary approach that combines an oleophobic coating application and the sheet-metal-forming process.

Comparison of Friction Properties of GI Steel Plates with Various Surface Treatments

“…The formability of steel plates and the shape of the final parts made from them depend on factors such as the material (its mechanical properties and surface microgeometry) [1,2]; the forming die geometry (die clearance, radii of the punch and die) and microgeometry (roughness of contact surfaces) [3][4][5]; the technological parameters (temperature, strain rate, blank holding forces, contact pressure, etc.) [6][7][8]; the properties of the tool's material (hardness, chemical composition, structure) [9]; and the type and amount of lubricant used [10]. During the deep drawing process, the individual parameters change and their mutual interaction has an influence on the formability, which is largely influenced by the lubricant or lubrication strategy.…”