Microinjection molding of substrates with graded micropillars

A. Almalki, A. Rajhi, A. Kundu, J. Coulter
Lehigh University,
United States

Keywords: microinjection molding, micropillars, bulk metallic glass, MoldFlow


In this research, a commercially available zirconium-based bulk metallic glass (BMG) material was utilized as a tooling insert for microinjection molding (μIM) of substrates with graded micropillars. The Zr-BMG alloy has the composition of Zr67 Cu10.6 Ni9.8 Ti8.8 Be3.8. The primary objective was to investigate the capability of the BMG tooling to produce such surfaces. Additionally, the influence of selected processing parameters on the molded parts was investigated. A focused ion beam (FIB) was utilized to mill circular microcavities with several depths on the BMG insert to achieve the graded surface. It has nominal depths ranging from 5 µm up to 60 µm with an increment of 5 µm. MoldFlow simulations were conducted before initial molding trials and the results of selected parameters from molding trials were compared with the simulation results. In this research two polymeric materials were utilized: thermoplastic polyurethane (TPU) and polystyrene (PS).