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사출성형에서 사출속도, 수지의 종류 및 금형 형상에 따른 젯팅 현상에 관한 고찰

Investigation of the Jetting Phenomena in Injection Molding for Various Injection Speeds, Resins and Mold Shapes

  • 류민영 (서울산업대학교 금형설계학과, 정밀기계기술연구소) ;
  • 최종근 (순천대학교 기계자동차공학부) ;
  • 배유리
  • 발행 : 2003.02.01

초록

The formation of surface defects associated with Jotting in injection molding is related to the geometries of cavity and fate, operational conditions and the rheological properties of polymer. In this study we have examined jetting phenomena in injection molding process for the throe kinds of PCs which have different molecular weights and structures, PBT and PC/ABS alloy with several injection speeds. We have used various cavity shapes those are tensile, flexural and impact test specimens with various gates and cavity thicknesses. Through this study we have observed that the jetting is related to the dic swell of material. This means that the jotting is strongly affected by the elastic flow property rather than the viscous flow property in viscoelastic characteristics of molten polymer. Different resins have different elastic properties, and elastic flow behavior depends on the shear rate of flow, i.e. injection speed. Large die swell would eliminate jetting however, the retardation of die swell would stimulate jetting. In the point of mole design, reducing the thickness ratio of cavity to gate can reduce or eliminate jetting regardless of amount of elasticity of polymer melt.

키워드

참고문헌

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피인용 문헌

  1. The Relation between Injection Molding Conditions and Gloss of ABS Molding vol.14, pp.11, 2013, https://doi.org/10.5762/KAIS.2013.14.11.5352