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Investigation of wave‐like flow marks in injection molding: Flow visualization and micro‐geometry
Author(s) -
Tredoux Louis,
Satoh Isao,
Kurosaki Yashuo
Publication year - 1999
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11611
Subject(s) - materials science , flow (mathematics) , flow visualization , molding (decorative) , geometry , visualization , engineering drawing , mechanics , composite material , mechanical engineering , engineering , physics , mathematics
The wave‐like flow mark phenomenon is one of the surface defects that can occur during the injection stage of the injection molding process. The generating mechanism of this phenomenon is not yet well understood. In this paper the flow mark generation mechanims is investigated by (i) directly observing the behavior of the polymer in the flow front and contact line areas under molding conditions when flow marks are generated, and (ii) studying the micro‐geometry of the flow marks after molding. Specific attention was given to (i) the point of origin of flow marks (relative to the moving contact line, as well as the history along the flow path), and (ii) the effect of thermal boundary conditions on the micro‐geometry of flow marks. These findings and their significance in relation to the flow mark generation mechanism are discussed. It is proposed that the flow marks are caused by nonuniform thermal contraction in the solidifying layer immediately behind the contact line.