3-D printing of complex structures by selective deposition is currently dominated by direct write and inkjet technologies (as utilized in Stratasys, Objet, ZCorp, Voxeljet, and Solidscape systems). Dry toner systems, despite their high productivity and maturity in 2D digital printing, have only been used indirectly for Additive Manufacture (AM) of objects above the micro scale. For over 3 years a European consortium has sought to overcome the inherent challenges of multilayer printing by electrophotography to enable its use in mainstream AM which promises increased deposition efficiency and a means of utilizing materials not amenable to liquid ink formulations. This paper reviews the challenges addressed and demonstrates the progress made including development of a bespoke thermoplastic elastomer toner and the specialized hardware configuration used to print and fuse it into tensile specimens over 50 layers thick which elongated over 500% before failure. Additionally, seeking to reduce oxidation during toner fusing, electrostatic printing and fusing was unsuccessfully attempted in a vacuum and in argon; while printing in a partial vacuum (above 50 kPa) and nitrogen was possible.
Jason Jones, David Wimpenny, Greg Gibbons, Chris Sutcliffe, "Additive Manufacturing by Electrophotography: Challenges and Successes" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP26), 2010, pp 549 - 553, https://doi.org/10.2352/ISSN.2169-4451.2010.26.1.art00046_2