PET-Hair Generating Mechanism of Laminated Steel in Forming Process of DI Can

Abstract

On application of polyethylene terephthalate (PET) film laminated steel to Drawn and Ironing (DI) process, it is necessary to control the PET-hair that we named shaving or breaking film at formed can edge due to no flange making in process. We previously reported the PET-hair was controllable with lower yield stress of steel substrate and stronger adhesion between PET film and the substrate. In this study, to demonstrate cause and mechanism of the PET-hair generation, we investigated the film adhesion to the substrate and the film peeled-off length at upper edge of formed can, and found a correlation between the two properties. The film peeled-off strength over 15N gets the film peeled-off length considerably shorten, resulting in difficulty in the PET-hair generation. Furthermore, we checked effects of ironing rate on the strain in the film during can-forming, and found the following mechanism. While ironing rate of 10% provides fracture strain in the film, strong adhesion could achieve no PET-hair generation even at the rate of over 10%. However, in case of the rate of over 15%, fracture of the film can’t be avoided, resulting in the PET-hair generation.