In this paper, the hydrophobic polymer surface with regular and controllable micro-textured structures was effectively and rapidly fabricated by micro-injection molding using a novel micro-textured mold machined by wire electrical discharge machining (WEDM). The phase constitutions of smooth and micro-textured mold surfaces were compared along with machined surface roughness of molds. The surface topographies of micro-textured molds and micro-injection molded polymers were characterized. The machining accuracy of WEDM for micro-textured mold and the replication rate of micro-injection molding for micro-textured polymer were calculated and analyzed. The wetting behaviors of smooth and micro-textured polymer surface were investigated together with the static contact angle and contact angle evolution versus time. The experimental results show that the maximum contact angle on the micro-textured polymer surface can reach to 127.5°, which was improved by about 71.6% compared with smooth polymer surface. It is shown that the highest machining accuracy of mold and the maximum replication rate of micro-injection molding can reach to 0.153% and 99.455%, respectively.

Precise micro-grinding machining was proposed to fabricate regular and controllable micro-grooved array structures on the surface of mold cores to realize the mass production and manufacturing of micro-structured polymer components by micro injection molding in this paper. First, the 3D topographies and section profiles of micro-ground mold cores and micro-formed polymers with different micro-structure parameters were presented. Then, the surface roughness of mold cores and polymers were compared. Next, the relationships between machining accuracy of mold core ground by micro-grinding and filling rates of micro-structured polymer formed by micro injection molding were investigated. Finally, the influences of micro injection molding parameters on the filling rate of micro-structures polymer were investigated. It is shown that the micro-structured polymer can be effectively and rapidly fabricated using the proposed method. The experimental results indicate the highest form accuracy of the micro-grooved mold core and the filling rate of micro-structured polymer can reach to 4.05 µm and 99.30%, respectively. It is found that the filling rate of the micro-structured polymer roughly increased with increasing machining accuracy of the mold core. The injection pressure had the greatest influence on the filling rate of the injection formed polymer, while the melt temperature had the least influence.