Design methodology for optimized die coatings: The case for aluminum pressure die-casting - Invited paper B7-1-1, ICMCTF, presented Monday May 2nd, 2005, San Diego

The overriding philosophy proposed in this paper is that of specifically designing an optimized die coating system, or range of systems, to meet each material forming application, rather than trying to make one coating or an available range of coatings fit a specific application. Many different die coatings are being used in material forming processes such as aluminum pressure die casting, metal stamping, plastic molding, and glass forming, with different levels of success. This paper presents an optimized design methodology that is based on a multi-layered and graded coating system that first identifies the most appropriate working layer that has minimal chemical interaction with the material being formed, an intermediate layer that accommodates the residual thermal stresses induced by the forming cycle, and an engineered adhesion layer that provides strong adhesion of the coating system to the substrate. In addition the substrate can also be subjected to a surface modification treatment that will provide an improvement in the mechanical properties of the substrate surface to better support the coating system. This methodology is achieved using laboratory testing, simulated and in-plant die casting trials, and modeling in an effort to generate a fundamental understanding of how such optimized die coating systems may be designed. In order to achieve this objective, a fundamental understanding of how such die coatings degrade and fail is also of importance. This methodology has been specifically applied to design optimized coating systems for aluminum pressure die-casting dies. (c) 2006 Elsevier B.V. All rights reserved.