Thin‐wall injection molding of polypropylene using molds with different laser‐induced periodic surface structures

Research output: Contribution to journalArticle

Authors

Colleges, School and Institutes

External organisations

  • University of Massachusetts Lowell
  • University of Padova

Abstract

In injection molding, high pressure is required to completely replicate the mold geometry, due to the viscosity of thermoplastic polymers, the reduced thickness of the cavity and the low mold temperature. The reduction of the drag required to fill a thin-wall injection molding cavity can be promoted by inducing the strong slip of the polymer melt over the mold surface, which occurs within the first monolayer of macromolecules adsorbed at the wall. In this work, the effects of different Laser-Induced Periodic Surface Structures (LIPSS) topographies on the reduction of the melt flow resistance of polypropylene were characterized. Ultrafast laser processing of the mold surface was used to manufacture nano-scale ripples with different orientation and morphology. Moreover, the effects of those injection molding parameters that mostly affect the interaction between the mold surface and the molten polymer were evaluated. The effect of LIPSS on the slip of the polymer melt was modelled to understand the effect of the different treatments on the pressure required to fill the thin-wall cavity. The results show that LIPPS can used to treat injection mold surfaces to promote the onset of wall slip, thus reducing the injection pressure up to 13%.

Details

Original languageEnglish
Pages (from-to)1889-1896
JournalPolymer Engineering and Science
Volume59
Issue number9
Early online date19 Jul 2019
Publication statusPublished - Sep 2019

Keywords

  • thin-wall injection molding, laser-induced periodic surface structures, wall-slip, reduction of melt flow resistance, mold surface engineering