Manufacturing Signatures of Injection Molding and Injection Compression Molding for Micro-Structured Polymer Fresnel Lens Production

Dario Loaldi*, Danilo Quagliotti, Matteo Calaon, Paolo Parenti, Massimiliano Annoni, Guido Tosello

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Injection compression molding (ICM) provides enhanced optical performances of molded polymer optics in terms of birefringence and transmission of light compared to Injection molding (IM). Nevertheless, ICM requires case-dedicated process optimization to ensure that the required high accuracy geometrical replication is achieved, particularly especially in the case of surface micro-features. In this study, two factorial designs of experiments (DOE) were carried out to investigate the replication capability of IM and ICM on a micro structured Fresnel lens. A laser scanning confocal microscope was employed for the quality control of the optical components. Thus, a detailed uncertainty budget was established for the dimensional measurements of the replicated Fresnel lenses, considering specifically peak-to-valley (PV) step height and the pitch of the grooves. Additional monitoring of injection pressure allowed for the definition of a manufacturing signature, namely, the process fingerprint for the evaluation of the replication fidelity under different process conditions. Moreover, considerations on the warpage of parts were related to a manufacturing signature of the molding processes. At last, the global part mass average and standard deviation were measured to correlate local geometrical replication performances with global part quality trends.
Original languageEnglish
Article number653
JournalMicromachines
Volume9
Issue number12
Number of pages21
ISSN2072-666X
DOIs
Publication statusPublished - 2018

Keywords

  • Manufacturing signature
  • Process fingerprint
  • Fresnel lenses
  • Injection compression molding
  • Injection molding
  • Micro structures replication
  • Confocal microscopy
  • Optical quality control
  • Uncertainty budget
  • Optimization

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