Influence of injection molding parameters on the quality of structured surfaces

Schaible, Tobias; Schönlein, R.; Bonten, Christian

doi:10.1063/5.0029147

Cited by 5 publications

(1 citation statement)

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“…Form filling and adequate demolding, already challenging in the molding of microfeatures, become even more delicate when replicating features at the submicron level. While the filling of cavities is attributed to the melt injection temperature and mold temperature [ 9 , 10 , 11 ], these replication-enhancing parameters also affect the demolding forces [ 12 ]. Acting forces in injection molding are the thermal contraction force related to the polymer, friction forces, adhesive forces and stiction, as well as a deformation force during the ejection stage [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Direct Processing of PVD Hard Coatings via Focused Ion Beam Milling for Microinjection Molding

2023

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Hard coatings can be applied onto microstructured molds to influence wear, form filling and demolding behaviors in microinjection molding. As an alternative to this conventional manufacturing procedure, “direct processing” of physical-vapor-deposited (PVD) hard coatings was investigated in this study, by fabricating submicron features directly into the coatings for a subsequent replication via molding. Different diamondlike carbon (DLC) and chromium nitride (CrN) PVD coatings were investigated regarding their suitability for focused ion beam (FIB) milling and microinjection molding using microscope imaging and areal roughness measurements. Each coating type was deposited onto high-gloss polished mold inserts. A specific test pattern containing different submicron features was then FIB-milled into the coatings using varied FIB parameters. The milling results were found to be influenced by the coating morphology and grain microstructure. Using injection–compression molding, the submicron structures were molded onto polycarbonate (PC) and cyclic olefin polymer (COP). The molding results revealed contrasting molding performances for the studied coatings and polymers. For CrN and PC, a sufficient replication fidelity based on AFM measurements was achieved. In contrast, only an insufficient molding result could be obtained for the DLC. No abrasive wear or coating delamination could be found after molding.

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