Design & Manufacturing

Korean Society of Die & Mold Engineering (한국금형공학회)
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A study on the effects of polymer core gate sizes on thickness shrinkage rate

폴리머코어 게이트 크기 변화가 두께 방향 수축률에 미치는 영향에 대한 연구

  • Choi, Han-Sol (Dept. of Mechanical Engineering, Dankook University) ;
  • Jeong, Eui-Chul (Dept. of Mechanical Engineering, Dankook University) ;
  • Park, Jun-Soo (Molds and Dies Technology Group, Korea Institute of Industrial Technology) ;
  • Kim, Mi-Ae (Molds and Dies Technology Group, Korea Institute of Industrial Technology) ;
  • Chae, Bo-Hye (Molds and Dies Technology Group, Korea Institute of Industrial Technology) ;
  • Kim, Sang-Yun (Molds and Dies Technology Group, Korea Institute of Industrial Technology) ;
  • Kim, Yong-Dae (Molds and Dies Technology Group, Korea Institute of Industrial Technology) ;
  • Yoon, Kyung-Hwan (Dept. of Mechanical Engineering, Dankook University) ;
  • Lee, Sung-Hee (Molds and Dies Technology Group, Korea Institute of Industrial Technology)
  • 최한솔 (단국대학교 기계공학과) ;
  • 정의철 (단국대학교 기계공학과) ;
  • 박준수 (한국생산기술연구원 금형기술그룹) ;
  • 김미애 (한국생산기술연구원 금형기술그룹) ;
  • 채보혜 (한국생산기술연구원 금형기술그룹) ;
  • 김상윤 (한국생산기술연구원 금형기술그룹) ;
  • 김용대 (한국생산기술연구원 금형기술그룹) ;
  • 윤경환 (단국대학교 기계공학과) ;
  • 이성희 (한국생산기술연구원 금형기술그룹)
  • Received : 2019.12.16
  • Accepted : 2020.03.31
  • Published : 2020.03.31
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Abstract

In this study, the variation of the shrinkage in the thickness direction of the molded parts according to the gate size of the polymer core fabricated through the 3D printer using the SLS method was studied. The polymer cores are laser sintered and the powder material is nylon base PA2200. The polymer cores have lower heat transfer rate and rigidity than the metal core due to the characteristics of the material. Therefore, the injection molding test conditions are set to minimize the deformation of the core during the injection process. The resin used in the injection molding test is a PP material. The packing condition was set to 80, 90 and 100% of the maximum injection pressure for each gate size. The runner diameter used was ∅3mm, and the gates were fabricated in semicircle shapes with cross sections 1, 2, and 3 ㎟, respectively. Thickness measurement was performed for 10 points at 2.5 mm intervals from the point 2.5 mm away from the gate, and the shrinkage to thickness was measured for each point. The shrinkage rate according to the gate size tends to decrease as the cross-sectional area decreases as the maximum injection pressure increases. The average thickness shrinkage rate was close to 0% when the packing pressure was 90% for the gate area of 1mm2. When the holding pressure was set to 100%, the shrinkage was found to decrease by 3% from the standard dimension due to the over-packing phenomenon. Therefore, the smaller the gate, the more closely the molded dimensions can be molded due to the high pressure generation. It was confirmed that precise packing process control is necessary because over-packing phenomenon may occur.

Keywords

Acknowledgement

Supported by : 산업통상자원부

본 연구는 산업통상자원부 산업기술혁신사업 자동차부품기업활력제고사업(20005905(PKM19H110))에 의해 수행되었으며, 이에 관계자 여러분께 감사드립니다.

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