Tanaka, A. and Sato, I., "Development of Improved Method for Magnetically Formed Decorative Painting," SAE Int. J. Mater. Manf. 8(1):187-206, 2015, doi:10.4271/2014-32-0045.
Currently, there is a growing demand for application of plastic coverings for motorcycles in the market. Accordingly, decorative features for plastic coverings are increasingly important to enhance the attractiveness of exterior designs of those motorcycles.Under these circumstances, the magnetically formed decorative painting had been adopted to a mass-production model sold in Thailand in 2008.Magnetically formed decorative painting is a method in which the design patterns are formed by painting a material that contains flakes movable along with magnetic fields, while applying magnetic sheets in the ornamenting design shapes underneath the part being painted. It offers a three-dimensional appearance even though its surface has no protrusions or indentations.The degree of three-dimensionality on the paint surface appearance was defined as “plasticity”  (a term used in pictorial arts). In our development, a challenge was made to create higher plasticity compared to the painting developed in 2008.It was understood that the orientations of the flakes had significant influences on the plasticity and our development goal was set to create a method that makes the flakes easily movable and yet discontinues the movements after the flakes settled at the desired orientations.The controllability of the flakes was realized by using the flakes with high magnetic permeability (Appendix 5) and by applying high-molecular-weight resin to the paint resin. In addition, by making the optimized selection of the thinner, movements of flakes were controlled during the drying process.By implementing those measures, high-plasticity design patterns was successfully realized for mass production.