On the reduction of gloss property of organic coated sheet metals after forming (vol 4, pg 1, 2010)

Organic coated sheet metals (OCSM) are widely used in many industrial applications such as automobile or electrical appliances because of their corrosion resistance and satisfaction of ecological requirements. Nevertheless, original functions of the very thin coating layer in OCSM products may be altered after being formed which consequently leads to a reduction of the product's quality. This paper deals with the reduction of gloss property of OCSM products. A forming limit diagram (FLD), a forming limit diagram of the coating layer (FLDC) of OCSM and a forming diagram for the prediction of gloss reduction are determined by using Nakajima tests. The Nakajima tests are performed with predefined strain states of the specimen. The experimental results show the dependency of the FLDC curve and the gloss reduction on both the equivalent strain and the strain ratio. Deep-drawing tests prove the applicability of the determined forming diagrams to predict coating fracture and gloss properties of OCSM after sheet metal forming and, thus, their potential as a tool for the process design for OCSM products.