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Issue 38, 2017
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Weld formation during material extrusion additive manufacturing

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Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical performance relative to those from traditional means; moreover, fundamental knowledge of the factors leading to development of inter-layer strength in this highly non-isothermal process is limited. In this work, we seek to understand the development of inter-layer weld strength from the perspective of polymer interdiffusion under conditions of rapidly changing mobility. Our framework centers around three interrelated components: in situ thermal measurements (via infrared imaging), temperature dependent molecular processes (via rheology), and mechanical testing (via mode III fracture). We develop the concept of an equivalent isothermal weld time and test its relationship to fracture energy. For the printing conditions studied the equivalent isothermal weld time for Tref = 230 °C ranged from 0.1 ms to 100 ms. The results of these analysis provide a basis for optimizing inter-layer strength, the limitations of the ME process, and guide development of new materials.

Graphical abstract: Weld formation during material extrusion additive manufacturing

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Publication details

The article was received on 11 May 2017, accepted on 10 Aug 2017 and first published on 11 Aug 2017

Article type: Paper
DOI: 10.1039/C7SM00950J
Citation: Soft Matter, 2017,13, 6761-6769
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    Weld formation during material extrusion additive manufacturing

    J. E. Seppala, S. Hoon Han, K. E. Hillgartner, C. S. Davis and K. B. Migler, Soft Matter, 2017, 13, 6761
    DOI: 10.1039/C7SM00950J

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