Experimental and simulation studies of micro blanking and deep drawing compound process using copper sheet

Microforming process is a promising micromanufacturing technology for producing microparts due to its high efficiency, low production cost and good product quality. The occurrence of size effect in the process, however, leads to the uncertainties in process determination, tooling design and product quality control and renders the design full of challenges. In-depth study of material deformation behavior in microforming process is thus crucial for development of quality microparts. In this research, the micro compound blanking and deep drawing of copper sheet is conducted. To investigate the size effect, the similarity theory is employed in die design and deformation process simulation. The grain size effect is studied by preparing the copper sheets with different grain sizes, while the feature size effect is also studied via using different punch radii. Based on the analysis of experimental results, it is found that the deformation load decreases with the increase of grain size, but this decrease is not significant when there are only a few grains in the cross section of the sheet metal. The deformation becomes inhomogeneous with the decrease of formed part size and the increase of grain size. This further leads to the irregular geometry and rough surface finish of the formed part. Furthermore, the simulation is carried out to reveal the entire deep drawing process. The deformation loads predicted by simulation have the same trend as the experimental ones, but the difference exists in-between. This indicates that the simulation of microforming process needs to consider the inhomogeneous deformation of material in the process.