Vat photopolymerization using pulsed exposure

Abstract

Vat photopolymerization (VP), a subcategory of additive manufacturing (AM), enables the fabrication of custom and intricate 3D structures essential to micro-nano engineering. However, research on VP's main parameters, irradiance and exposure time, remains limited. This study focuses on digital light processing (DLP), a subgenre of VP, to investigate a new way to manufacture samples: the pulsed exposure method. Based on previous work, we expect this emerging technique to i) prevent undercuring, ii) increase edge and corner definitions, and iii) enhance surface appearance. We used a custom-built photo projector that we qualified against a comparable commercial device to investigate the influence of different illumination duty cycles (100 %, 67 %, 50 %, and 33 %) on one-layer samples. The results positively verified our hypotheses, as using the pulsed exposure method prevents undercuring, yields straighter edges and sharper corners, and improves the surface smoothness. Furthermore, we observe a clear trend that a lower duty cycle has a stronger effect. These findings suggest that the pulsed exposure method is a promising new way to manufacture samples using VP. This study is the first to analyse the influence of the duty cycle in pulsed exposure and paves the way for future advancements in scalable, efficient, and precise additive manufacturing of polymer.

Keywords

• VP
• DLP
• Curing method
• Pulsed exposure
• Duty cycle