Influence of temperature on deformation behavior of copper during microextrusion process

Abstract

Micro scale deformational behavior of metals is improved upon increasing the room temperature. Further, the drawbacks of micro forming caused by size effects are reduced significantly. In the current work, investigation on the material behavior of copper at elevated temperature ranging from room temperature to 200 ℃ is conducted. On the experimental part, a novel micro extrusion die set assembly has been developed along with temperature assistance, where the specimen is heated within the die assembly to study deformation behavior. When the forming temperature is raised, an enlargement of the forming limits is achieved along with a significant reduction in extrusion force. Further, the flow of material inside the die orifice was more uniform, and the micro pin showed a good replication of the die dimensions with homogeneous material deformation. During the increase of extrusion temperature and lubrication conditions (diamond-like carbon coating), the micro pin is more complete with higher dimensional accuracy and surface finish. The investigation on the influence of temperature showed that there is a reduction in microhardness of samples compared to the hardness of samples extruded at room temperature. However, there is a significant reduction of scattering due to homogenizing effect.

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

“…Further, friction increases significantly due to the non-appearance of lubricant and surface coating, which results in the lowest pin length. In the case of servo lubricant being used, it could not be retained inside the die cavity as it is easily squeezed out from the die wall surface [7]. But when the extrusion die is coated with diamond-like carbon (DLC), the flow of material inside the die cavity is more uniform with minimum resistance resulting in the most significant pin length.…”

“…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. Qin [8] describes the dimension of microparts varying from sub millimeters up to a few millimeters used extensively in electronics and micromechanical products.…”

“…This causes troubles, such as non-uniform deformation and large scatter, resulting in restrictions on product reproducibility. The effect of elevated temperature on extrusion force, force resistance, microhardness, and surface finish of pure copper was investigated by Nandhakuar et al [7]. Bhupatiraju et al [21] investigated the punch pressure in a cold extrusion process.…”