日本金属学会誌

J. Japan Inst. Metals, Vol. 70, No. 7 (2006),
pp. 568-571

Evaluation of Pore Defects in Die Casting Using Fractal Dimensions

Yoshihiko Hangai1, Shunsuke Yoshida1,, Soichiro Kitahara2 and Shigeyasu Amada1

1Department of Mechanical System Engineering, Faculty of Engineering, Gunma University, Kiryuu 376-8515
2Gundai Co., Ltd., Isesaki 372-0854

Abstract:

The pore defects inside die casting have an influence on the mechanical properties or air leakage efficiency of products. In these days, the classification of these pore defects is not clearly determined, and accurate measures to reduce these pore defects in the production field are carried out by trial-and-error processes. The accurate classification of pore defects leads to the accurate clarification of the direct cause of these defects. For this purpose, it is necessary to estimate pore defects quantitatively, instead of qualitatively. We propose the fractal dimension as the quantitative indicator of the classification of pore defects. In this study, we examined the fractal analysis of the shapes of ``blow hole'' and ``shrinkage porosity'', and the validity of applying fractal dimensions to pore defects is investigated. The fractal dimensions for shapes of boundary lines for ``blow hole'' and ``shrinkage porosity'' are about 1.05∼1.09 and about 1.15∼1.17, respectively. Therefore, it is shown that the quantitative classification of ``blow hole'' and ``shrinkage porosity'' using fractal dimensions is definitely feasible.


(Received 2005/10/25)

Keywords:

fractal dimension, die casting, ADC12 aluminum alloy, blow hole, shrinkage porosity


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