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The press forging of AZ31 magnesium-alloy sheets for producing thin-walled structural components used in the electronics industry was examined by both the finite element analysis and the experimental approach in the present study. The experimental results obtained from the compression tests and ring compression tests were employed in the finite element simulations to investigate the effects of process parameters, such as forming temperature, friction condition, embossment location, and sheet thickness on the formation of embossments in a press forging process. The finite element simulation results reveal that a cost-effective press forging process of AZ31 magnesium-alloy requires an optimum combination of the above parameters. The detailed examination of the effects of the process parameters on the formation of embossments made in the present study could provide a design guideline for a press forging process of AZ31 magnesium-alloy sheets.

Micro-metal forming technologies are mass production methods, net shape forming, low-cost procedures and quality controlled processes. Its scale region is in the range of the margin area between conventional precision manufacturing and silicon-based technology. The first paper to study the field of micro metal forming was written in 1989. Up to now, there have been many papers in this field but the results of the experiments do not reach the same conclusions. It should be noted that it is not possible to apply the know-how of conventional forming processes to the field of micro-metal forming due to the so-called size effects. In this study, two kinds of sheet materials such as C12000 and C26000 copper alloys are used to do a micro-upsetting experiment and micro-tensile experiment. It can be found that the size effects of micro-metal forming in C12000 agree with the description in previously published papers. However, the C26000 alloy has high matrix strength and significant fine grain strengthening that produce different size-effects of micro-metal forming. In this paper, we compare these two materials and suggest explanations for this problem. Therefore, the result can provide a general solution and discussion of micro-metal forming processes in unalloyed copper and brass.

With the ongoing development of product process, there is a growing demand on micro products. Though the macro-drawing process has been well-developed, the design concepts may not be directly applicable to the micro-drawing due to the size effect occurred in the micro-forming processes. In the present study, experiments were conducted first to establish the stress-strain curves, r-values and work hardening exponents of 304 stainless steel sheets with different grain sizes. The experiment results reveal that the stress-strain and r-value become smaller and the work hardening exponent increases for larger grain sizes. The difference between stress-strain curves in various directions of 0°, 45° and 90°, respectively, is significant when the grain size increases. The stamping of a vibration motor shell of cell phone, which bears a circular cylindrical shape, was also examined in the present study. The finite element simulations were performed to evaluate the formability of the multi-stage drawing process with initial die design. The forming characteristics were identified and an optimum die design was then developed with the use of the finite element analysis. The stamping process with multi-stage tooling design based on the finite element analysis was implemented and the actual stamping experiments were conducted to verify finite element analysis. The experimental results confirm the validity of the modified tooling design and the efficiency of the finite element analysis.

Due to the requirement of lightweight in the automotive body structure design, the application of advanced high strength steel (AHSS) has been widely adopted in the automotive industry. However, the technical difficulties are also experienced in the forming process of stamping the advanced high strength steel. One of the major defects is springback. In this study, both the experimental approach and the finite element analysis were adopted to examine the springback phenomenon occurred in the stamping of a front bumper inner made of 590Y advanced high strength steel. The die compensation approach was employed to adjust the amount of springback to make the dimension of the automotive part conforming to the design specification. The accurate dimension of the production part validates the finite element analysis and the die compensation approach adopted in the present study provides a useful guideline for improving the springback defect in the stamping of advanced high strength steel sheets.