Journal of the Society of Materials Science, Japan
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
Effect of Closing Speed on Flow State of BMC
Tuneo HIRAITutao KATAYAMATeruo KIMURAToshikazu ISHISEHiroyuki HAMADA
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Keywords: BMC
JOURNAL FREE ACCESS

1979 Volume 28 Issue 315 Pages 1218-1224

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Abstract

In the field of composite materials, such as glass fiber reinforced plastics, the molding process using a matched die is attracting wide attention as a mass production technology. BMC has been developed for the process, but it seems to have some troubles. One of them is a surface appearance with thin wall. Another one is brittle weakness at the bottom of a fin portion caused by a stress concentration in the resin rich fillet part.
In order to prevent these troubles, it is necessary to investigate the flow state of BMC during the molding process. In BMC glass fibers are randomly oriented at the initial state. However, in order to prepare a specimen with fibers oriented initially in the flow direction, a block of BMC is prepressed from 50mm to 6mm in its height. So, the flow of BMC shows an anisotropic nature, such as different fluid resistances in normal and parallel directions to the flow, as reported in the previous paper.
In this paper, the dependence of flow state of BMC on the closing speed and the influence of temperature were considered. At first, the experiments were carried out at room temperature so as to avoid the effect of polymerization and obtain only the effect of closing speed. Then the experiments were made at 110°C, which is close to the actual product condition.
The results indicate that the flow state of BMC shows more anisotropic nature with increasing closing speed. With decreasing closing speed, the troubles described above disappear at room temperature but at 110°C only a limited closing speed prevents the troubles. And the“surge phenomenon” appears remarkably with increasing speed.

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