Numerical analysis and experimental investigation of surface defects in die hemming process


Hemming is the main assembly process used for auto-body panels. Surface defects resulting from the hemming operation may significantly influence the appearance aesthetics of an automobile. The formation of surface defects can be forestalled, and the process can be optimized and compensated by the numerical simulation method during the process design stage. In this study, the hemming assembly of a fuel tank cap is chosen as the research object, and the specimen is made of DX54D + Z deep drawing steel sheet. Numerical simulation and forming experiments have been carried out. It was found that the surface defect index can be expressed as the weighted sum of the design variable effects by simulation and orthogonal design. In addition, the magnitude of each effect can be ranked from the most significant to the least significant. Using this information helps to obtain an optimal hemming process plan. However, process parameter optimization cannot completely eliminate surface defects. The surface compensation of tool geometry based on the continuity of curvature was used to eliminate the surface lows and the hemming test results indicated that the obtained component was of the required quality.

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The authors are grateful to FAW Tooling Die Manufacturing Co., Ltd. for their valuable help in the experimental part.


This study was funded by the Technology Development Program of Jilin Province (20160204058GX).

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Correspondence to Gang Wang.

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Wang, G., Gu, Z., Xu, H. et al. Numerical analysis and experimental investigation of surface defects in die hemming process. Int J Mater Form 13, 91–102 (2020).

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  • Surface defect
  • Die hemming
  • Numerical simulation
  • Process optimization
  • Surface compensation