Effects of Initial Slug Design on the Earring of a Rectangular Battery Case During Impact Extrusion

충격압출 공정에서 초기 슬러그 디자인이 사각 배터리 케이스의 이어링에 미치는 영향 분석

Lim, J. H.;Choi, S.;Chung, W. J.;Shin, J. H.;Lee, J.

  • Received : 2015.10.06
  • Accepted : 2015.11.19
  • Published : 2015.12.01


In the current paper, the effects of initial slug design on the earring of an Al rectangular battery case manufactured by impact extrusion were studied. During impact extrusion, non-uniform metal flow between the long and the short sides of the battery case leads to earring, which is subsequently trimmed. Process parameters such as friction, aspect ratio of the battery case, the die shape and the forming temperature tend to induce earring because they cause greater non-uniform metal flow. Large aspect ratio of the battery case and high friction between slug and die can greatly affect the earring of a rectangular battery case. To make a rectangular battery case without earring, it is necessary to control metal flow uniformly during impact extrusion. One of the ways to reduce the earring is to control the metal flow of slug at the initial upsetting stage. To analyze the effects of the initial slug design on earring, FE analysis was conducted using DEFORM 3D. Two types of initial slug designs were evaluated where volume was removed along either the width or thickness directions. The results show that the initial slug design can be effective in adjusting the uniformity of metal flow.


Impact Extrusion process;Initial Slug Design;Metal Flow;Earring


  1. E. Romhanji, M. Dudukovska, D. Glisic, 2002, The Effect of Temperature on Strain-rate Sensitivity in High Strength Al-Mg Alloy Sheet, J. Mater. Process. Technol., Vol. 125-126, pp. 193~198.
  2. S. H. Kim, S. W. Chung, S. Padmanaban, 2006, Investigation of Lubrication Effect on the Backward Extrusion of Thin-walled Rectangular Aluminum Case with Large Aspect Ratio, J. Mater. Process. Technol., Vol. 180, Issue 1-3, pp. 185~192.
  3. T. Watanabe, M. Motomura, A. Hagiwara, G. Konishi, 2012, Investigation on Defects Generation Mechanism and Method for Reducing Defects in Impact Extrusion of Battery Cases for Vehicles, Jpn. Light Metal., Vol. 62, No. 10, pp. 363~369.
  4. J. Danckert, 2004, The Influence of the Punch Land in Backward can Extrusion, CIRP Annals, Vol.53, Issue 1, pp. 227~230.
  5. S. H. Kim, S. W. Chung, 2005, Investigation of Sectional Aspect Ratio on the Backward Extrusion Process of Aluminum Container, Kor. CAD/CAM, Vol. 2005, No.1, pp. 950~956.
  6. S. H. Kim, S. H. Kim, H. Huh, 2001, Finite Element Inverse Analysis for the Design of Intermediate Dies in Multi-stage Deep-drawing Processes with Large Aspect Ratio, J. Mater. Process. Technol, Vol. 113, No. 1, pp. 779~785.