Flat receptacle, which is used in extruding the large aluminum profiles, is in harsh work conditions. Due to the irregularity of inner hole of flat receptacle, inconsistent resistance of shrinking fitting affects the inner hole within which nonuniform deformation occurs. If the nonuniformity exceeds the specified dimension accuracy, tiresome work including mould repairing and structure optimization has to be done. ANSYS is used to simulate the flat receptacle. It is shown that the maximum stress appears in the arc area of inner hole. Therefore, we present one new method using the preloaded layer with changeable shrinkage to replace the preloaded layer with uniform shrinkage. Considering the processing and assembling factors, we adopt the elliptical outer layer and circular inner layer as the new structure. Then the optimizations of flat receptacle with uniform and changeable shrinkage are implemented using the optimizing module, receptively. The optimized results show the maximum equivalent stress in the corner of inner-hole decreases about 5.47% if adopting the changeable shrinkage. The numerical simulation results show that the feasibility of changeable shrinkage and elliptical preloaded layer.

With the rapid development of MEMS and electronic industry, the demands for micro-parts are increasing gradually. However, size effects make the traditional forming theories and deformation mechanism not suitable in micro forming field. In this paper, we introduced the classification of the size effects. It pointed out that the size effects can be divided into the first order and the second order size effects in the micro-forming. For the first order size effects, the theory model was established based on the surface layer model. It also clarified the phenomenon that flow stress of the blank reduced with the increase of the ratio of grain size and thickness (t decreases or d increases). Finally, the model was verified with the experimental results of the first order size effects in the references, confirming the effectiveness of the theoretical model. It provides a method to theoretically and experimentally study the micro-plastic forming.

The rapid market need of MEMS (Micro Electromechanical System) and metal microparts are increasing gradually. The plastic microforming has received more interests and applications in MEMS because it ensures high precision and manufacturing efficiency. However, it raises the higher demand on the microforming and plastic processing technology. Here we present one new process to micro-extrude microparts with laser-aided heating method. The new process is to selectively heat the workpiece with the laser radiation method to the suitable temperature that is between room temperature and recrystallization temperature, and to extrude the workpiece. This process is characterized by decreasing the influence of strain strengthening and lowering the resistance to deformation, and increasing the uniformity of material flow. The key elements of the approach concerning the warm micro-extrusion and temperature control, such as process parameters, laser heating system, micro-extrusion die structure, have been advanced. Furthermore, an important aspect of the research is that the developed system and theory of micro warm extrusion based on laser heating can be explored for further investigation and understanding of plastic microforming.