Influence of grain size on deformational behavior in microextrusion process

Abstract

Miniaturization drives the need for developing appropriate technology for microproducts of extremely small geometric features with high tolerances. In this work, the authors have investigated the material behavior and size effect in microextrusion of pure copper and aluminum with different grain sizes. A forward microextrusion assembly has been developed in the first phase of work to investigate the grain size effects. The experimental results are then compared to finite element simulation to quantify force displacement response. It has been found that the simulated deformation load is comparable with experimental results. The influence of size effect in both copper and aluminum showed that the extrusion load and average microhardness of 38 μm and 34 μm are higher when compared to 204 μm and 124 μm. In the second phase of work, an attempt has been made to fabricate the copper microgear (m = 0.416 mm) by the developed extrusion setup. The findings of this work are essential for further development of micro-formed parts and will facilitate in introducing microextrusion for mass production of industrial components.

Experimental investigations of influence on grain size and cold deformational behavior of AL6063 during the microforming process

“…Many grain boundaries necessitate a higher deformation load and flow stress, resulting in higher hardness. The grain size is smaller at a significant number of grain borders [1,5,12,22].…”

“…To reduce the extrusion force, extrusion at elevated temperatures can experiment with, leading to lesser extrusion force and better forming. It is due to the dislocation of thermally activated grains at elevated temperatures [1]. In this view, further research actions are needed, leading to better results and understanding.…”

“…Manufacturing industries focus on mass production of micro parts, which are difficult to process using conventional methods due to high tooling costs and a lack of available tools for miniature products. Nanthakumar et al [1] and Rahman et al [2] fabricated a micro-stepped pin using miniature machine tools, and the problem faced with tool-based micromachining is the workpiece deflection. One of the micromanufacturing processes is micro-forming (Joo et al; Chern and Chuang; Rajenthirakumar et al; Razali et al; Nanthakumar et al) [3][4][5][6][7] and its cost-effective process for mass production of micro metallic parts which includes micropin, microgear, microstepped shaft, microbulged pin, micro screw, IC chips, facial implants, clavicle implant, and knee plate.…”

“…Liu et al [13] examine the size effect of H62 brass with the uniaxial tension experimentations, and the results show both the grain size effect and the feature size effect. The material behaviour and size effect in microextrusion of pure copper and aluminium with dissimilar grain sizes are investigated by Nandhakumar, and Rajenthirakumar [1]. Vollertsen [14] has classified the size effects into three categories as density effect, shape effect, and microstructure.…”

“…FE simulation was done by Rosochowska1 et al [18] to identify the process design before engaging in expensive experimental trials. Nanthakumar et al [1] and Zhengyi Jiang et al [19] investigated the behaviour of pure copper at elevated temperatures and highlighted the micro-scale deformational behaviour of the selected metals.…”