Effects of induced periodic surface structure technology on polymer filling flow and molded parts wettability in micro injection molding

In micro-injection molding, the specific cavity surface texture as well as its roughness directly influences the polymer flow and the heat transfer between polymer melt and mold. In this work a Nonlinear Laser Lithography (NLL) technology was employed to study its impact on the obtainable flow length in micro injection molding. A complete investigation of the surface treatment effect on the polymer flow was obtained comparing the performance of an untreated cavity surface with surfaces modified by NLL. The phenomenon was analyzed using different channels for melt separation and taking advantage of localization of weld lines for differential characterization. Several cavity inserts were developed by varying the NLL process parameters in order to generate surfaces with different micro-structures direction and periodicity. In this work, a further task regards the study of the hydrophobicity achieved on the micro molded surfaces, replicated from the mold inserts that were treated with different NLL process parameters. Both the mold inserts surfaces, NLL treated, and the molded parts were analyzed by means of optical profilometry and scanning electron microscopy to characterize the cavity surfaces replication and to localize the weld lines on the micro injection molded parts.