Abstract
Sheet Molding Compound (SMC) products such as one piece panel, have always stiffening ribs. In this product, some defects are observed. They are sink mark, weld lines, warpage and heat cracks. These defects are greatly influenced by the molding condition of SMC, especially material flow. In the design of the mold, the material flow is an important factor. But the material flow of SMC is complex and unsteady. So, CAD system of SMC is needed to design a molding die. Therefore, the present authors are constructing the data base to design the compression molding process of SMC.
In this paper, the flow characteristics and forming defects of SMC products were investigated. In flow characteristics, attention was paid to the branch of material flow around the rib part. To obtain the relation between flow characteristics and defects, the molding processes for T-shaped products were carried out by varying the charge pattern and the shape of the rib. Then the warpage was measured and the heat crack was observed. On the other hand, the data of fibre orientation was taken in the cross section of molding products.
Moreover, to construct CAD system of SMC, the thermal shrinkage in cooling down after the process was calculated by using the deformation model for the numerical analysis where SMC has the anisotropic homogeneity.
