1998 Fiscal Year Final Research Report Summary
Pheology and Heat Transfer Control of Microscale Instability Phenomena on Injection Molded Polymer Surfaces
| Project/Area Number |
09450086
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | UNIVERSITY OF ELECTRO-COMMUNICATIONS |
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Principal Investigator |
KUROSAKI Yasuo University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (70016442)
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| Co-Investigator(Kenkyū-buntansha) |
FUSHINOBU Kazuyoshi Tokyo Institute of Technology, Faculty of Engineering, Research Associate, 工学部, 助手 (50280996)
SATOH Isao Tokyo Institute of Technology, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10170721)
UCHIDA Yutaka University of Electro-Communications, Faculty of Electro-Commnications, Associat, 電気通信学部, 助教授 (00017336)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Injection Molding / Skin Layer / Super Precision Molding Technique / Biretringence / Surface Transcribability / Molding Limit / Flow Mark / Cooling Control |
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| Research Abstract |
The widely varying and still speculative nature of existing flow mark generation hypotheses indicated that there was no clear understanding of the generating mechanism yet. Based on the results of the literature study. two main research questions were formulated : (1) Provide a description of flow mark generation : Where, and how do wavelike flow marks generate? (2) Provide an explanation for flow mark generation : Construct an hypothesis for the mechanism by which wavelike flow marks are caused. Experiments were done to obtain the following information : (1) determination of the point of generation of flow marks, i.e., before, after, or at the contact line between the melt and the mold, and (2), observation of the actual generation process. This was accomplished using an injection molder equipped with a specially designed mold with an observation window. (3) Microscopic surface profile analysis after molding also played an important part in the experimental investigation. Specific attention was given to the effect of the thermal boundary conditions on the micro-geometry of flow marks. Analytical and numerical methods were used to model the heat transfer in the flow front and contact line areas. Phenomenological and mathematical models for explaining the flow mark generation mechanism were developed. The models are based on presumed thermal deformation of the solidifying layer in the area immediately behind the contact line. The mathematical model could be correlated with experimental data over a wide range of operating conditions and for three different materials. The main conclusion is that non- uniform thermal contraction in the solidifying layer behind the contact line appears to be the dominating factor in the mechanism by which wavelike flow marks generate.
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