ISBN 978-3-8396-1320-7 1 March 2018, Berlin / Germany www.ddmc-fraunhofer.de © Fraunhofer / DDMC 2018 Inkjet Printings on FFF printed curved surfaces Christian Wögerer* 1 , Michael Mühlberger 2 , Markus Ikeda 2 , Julia Kastner², Naresh Chowdary Chitturi², Andreas Pichler 2 1 PROFACTOR GmbH, Graumanngasse 7, 1150 Vienna, Austria 2 PROFACTOR GmbH, Im Stadtgut A2, 4407 Steyr-Gleink, Austria * Corresponding Author: Christian.woegerer@profactor.at Abstract We used robot guided inkjet printing to print graphical patterns on the surface of 3D freeform objects printed by Fused Filament Fabrication (FFF) Fused Filament Fabrication (FFF, also known and trademarked as "Fused deposition modeling", FDM [0]). Material tests as well as process development for robot guided inkjet printing on curved surfaces was carried out and evaluated. System concepts and intermediate results are presented. 1 Introduction Surface finishing of 3D printed objects is an important topic and many different methods and approaches have been taken using e.g. lasers [0][2], hot air [3], chemical [4][5][6] or mechanical means [7]. We want to use the method of inkjet printing to additively deposit functional materials to the surface of 3D printed objects. The use of inkjet printing is also motivated by the fact that both 3D printing and inkjet printing are digital methods and it is therefore easy to inkjet print a different pattern for each 3D printed object. In a first step we are investigating graphical patterns but at a later stage printing organic electronic devices is also envisioned. 2 Inkjet printing on 3D printed surfaces In the framework of the addmanu project [8][13] PROFACTOR [9] is developing the basics for a multi- material hybrid manufacturing technology based on InkJet printing. The main challenge is InkJet printing on 3D curved surfaces of parts which are pre-manufactured using additive manufacturing technologies. The goals are divided into 4 different parts:  Development of UV (ultra violet) curable inks for multi-material hybrid manufacturing technologies, which is done by project partner TIGER Coatings [8] and is not covered in this paper.  Research on printing processes using InkJet printing on FFF pre-manufactured free-form parts.  System and process development of free-form printing using a robot based InkJet printing system.  Development of a non-destructive quality control system using machine vision, which is a topic for an additional publication. To design a pilot system several challenges have to be met. Especially the robot based InkJet application of the print material to the right spot is based on existing and extensive Know-How of PROFACTOR. This includes 3D machine vision [10] extended robotics [11][12] that allows object position invariant print head positioning above the 3D-printed surface. Figure 1 shows a robot moving a surface inspection system across the 3D surface of a carbon fibre part for automotive applications. 3 First Results The first results include inkjet printing tests on flat 3D printed substrates, setting up of the robot assisted inkjet printhead and printing test with the robot on flat and curved objects. 3.1 Inkjet Printing on flat FFF printed substrates First InkJet printing trials were done on 3D printed surfaces (FFF) using a Heavy Duty Ink from TIGER Coatings. Used substrates were FFF printed parts without any pre-treatment. The material was white PLA (Polylactides from Orbi-Tech) [20], which was printed with a HAGE 3Dp-A2 printer in the labs of Figure 1: Photograph of a robot during surface inspection