Characterization of in-field additively manufactured polymer composites – hot and dusty environment

As part of the European Defence Agency (EDA) Operational Budget (OB) study “Additive Manufacturing Feasibility Study & Technology Demonstration” (EDA contract no. 16.ESI.OP.144), in-field 3D printing of objects, i.e. using additive manufacturing, has been demonstrated. The two contractors are Fundación Prodintec (Spain) and MBDA (France). A (self-sustained) container, containing different printers, as well as tools for design, pre- and post-processing of the printed objects has been established and transported (on land) to an air base in Zaragoza, Spain. Moreover, the container has been put onto a transport aircraft, airborne, and finally brought back to the same air base. The demonstration aims to show military personnel, in particular, the possibilities and current capabilities of in-field production of spare parts and objects using additive manufacturing (AM). A more detailed presentation of the project and its different strands (state of the art, demonstration and AM exhibition/conference), including more details about the experiences from the demonstration, as well as recommendations for further research and development within this area, can be found in the reports from the project. Part of the AM demonstration is related to the material properties of the objects when printed outside the regular (and stationary) factory or workshop. The printing conditions in field, such as temperature, humidity and sand/dust/particles will typically be different from factory/workshop conditions, and may not be possible to control or set. Such factors may influence the quality and properties of the printed objects, which will influence on the object’s performance and area of use. In this study performed by FFI, which supported the work done in the current EDA study on AM, the mechanical properties of standardized test specimens manufactured in the workshop/factory and in field have been characterized. In total, eight types of test specimens were produced by Prodintec. Four types of standardized test specimens were produced at Prodintec facilities in May 2017 in factory/workshop conditions. The same four types of test specimens were printed in the container in field during the exercise “European Advanced Airlift Tactics Training Course for 2017” (EAATTC17-3) in Zaragoza, Spain, in June 2017. As an overall conclusion, based on the test results from this study, no significant reduction or change in mechanical properties are experienced for the objects printed in field compared to those printed in more controlled workshop/factory conditions. It should, however, be noted that the produced specimens are not fully dense; the specimens have a cell-like internal structure. As the real cross-sectional area of the fracture surface is challenging to measure, the crosssectional area of a dense specimen is applied in the calculations. Again, as a result of this, the obtained parameter values included in the study for the specimen sets are much lower than what is reported by the material manufacturer and in other studies. Still, a comparison of printing under different conditions and locations, i.e. factory versus in-field, is relevant, and the overall conclusion is still valid.