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Mitigation and control of the overcuring effect in mask projection micro-stereolithography

O'Neill, Paul and Kent, Nigel J. and Brabazon, Dermot (2017) Mitigation and control of the overcuring effect in mask projection micro-stereolithography. In: 20th International ESAFORM Conference on Material Forming, 26-28 Apr 2017, Dublin, Ireland. ISBN 9780735415805

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Abstract

Mask Projection micro-Stereolithography (MPμSL) is an additive manufacturing technique capable of producing solid parts with micron-scale resolution from a vat of photocurable liquid polymer resin. Although the physical mechanism remains the same, the process differs from traditional laser-galvanometer based stereolithography (SL) in its use of a dynamic mask UV projector, or digital light processor (DLP), which cures each location within each 3D layer at the same time. One area where MPµSL has garnered considerable attention is in the field of microfluidics and Lab-on-a-Chip, where complex multistep microfabrication techniques adopted from the semiconductor industry are still widely used, and where MPµSL offers the ability to fabricate completely encapsulated fluidic channels in a single step and at low cost [1–3]. However, a significant obstacle exists in the prevention of channel blockage due to overcuring of the polymer resin [4, 5]. Overcuring can be attributed to the so-called ‘back side effect’ [2] which occurs during the build process as light from successive layers penetrates into the resin to a depth greater than the layer thickness. This effect is most prevalent in channels or features oriented horizontally (in a parallel plane to that of the build platform). Currently there are two main approaches in controlling the cure depth; 1. the chemical approach, which involves doping the resin material with a chemical light absorber [6–8]; and 2. by improving the system's hardware and optical elements to improve the homogeneity of the light dosage and control the cure depth [9]. Here we investigate a third approach through modification of the 3D CAD file prior to printing to mitigate for UV light leakage from successive build layers. Although used here in conjunction with the MPμSL technique, this approach can be applied to a range of SL techniques to improve printer resolution and enable production of internal features with higher dimensional accuracy.

Item Type:Conference or Workshop Item (Paper)
Event Type:Conference
Refereed:Yes
Uncontrolled Keywords:Additive Manufacturing; 3D printing; Stereolithography; Process control
Subjects:Engineering > Mechanical engineering
Mathematics > Mathematical models
DCU Faculties and Centres:Research Initiatives and Centres > Advanced Processing Technology Research Centre (APTRC)
DCU Faculties and Schools > Faculty of Engineering and Computing > School of Mechanical and Manufacturing Engineering
Published in:Proceedings of the 20th International ESAFORM Conference on Material Forming. AIP Conference Proceedings 1896(1). American Institude of Physics. ISBN 9780735415805
Publisher:American Institude of Physics
Official URL:http://dx.doi.org/10.1063/1.5008249
Copyright Information:© 2017 The Authors
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
Funders:Science Foundation Ireland (Grant Nos. 12/IA/1576 and 12/RC/2289, Naughton Foundation (Naughton Graduate Fellowship)
ID Code:22081
Deposited On:23 Oct 2017 14:30 by Mr Paul O'Neill. Last Modified 23 Oct 2017 14:30

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