Survivability of Laminated Polymer Lubricant Films in Ironing©

Abstract

Polymer-coated steels are of interest in the production of food and beverage containers because of their potential utility as solid lubricants and because of the potential elimination of a post-forming polymer spray operation which is time consuming and produces environmentally hazardous emissions. Unfortunately, little work has been done regarding formability of polymer-laminated steels in metal-forming operations, and this is especially true of the ironing process. This paper presents an experimental and theoretical investigation into the ironing formability of polymer coated steels. A strip ironing simulator is used to perform ironing tests at a large number of tooling geometries and thickness reductions. From the experiments, it is found that polymer coated steels will either iron successfully or will be shaved off of the substrate, and that the active mechanism depends most strongly on the die angle. An upper bound model is developed which predicts the circumstances under which successful ironing and shaving will occur and is supported by the experiments. This model allows base-stock providers to design better coatings for improved formability of polymer-coated steels. Presented at the 53rd Annual Meeting in Detroit, Michigan May 17–21, 1998