elchemPP (Land NÖ + WK NÖ)

A survey conducted in spring/summer 2018 on behalf of ecoplus (KC/MC) (Mag. (FH) DI Klaus Hitzenberger) revealed that the quality of 3D-printed metallic components, particularly regarding achievable tolerances and surface finishes, does not yet meet the expectations of potential customers. This finding aligns with the results of a study commissioned by the Lower Austrian Chamber of Commerce (WK NÖ) in autumn/winter 2017 (DI Ewald Babka) and with the insights gained by FOTEC from operating the LMI for 3D printing of metals. Information from Airbus DS, stating that post-processing costs for 3D-printed metallic components account for 30–40% of total manufacturing costs, further confirms the need for action, as this proportion is too high. The elchemPP project, co-financed by the European Regional Development Fund, is the logical and consistent further development of the "LMI for 3D Printing of Metals" at the consortium leader FOTEC Forschungs- und Technologietransfer GmbH. Its aim is to solve the problem of achievable surface finishes, as identified in the survey and study cited above, and to significantly reduce post-processing costs. To this end, a novel and automatable (and therefore industrially acceptable) electrochemical post-processing method will be tested in collaboration with consortium partners Fachhochschule Wiener Neustadt GmbH and Aerospace & Advanced Composites GmbH. This requires developing the technical and scientific foundations necessary to post-treat metals, which are crucial for 3D printing, while meeting high quality requirements.

Currently, the state of the art involves mechanically removing support structures from the component and then smoothing the surfaces, either mechanically or using various blasting techniques. The following methods are typically used for this purpose:

• Breaking away support structures at predetermined breaking points
• Milling (flat surfaces)
• Turning (cylindrical components or elements)
• Drilling (holes)
• Manual grinding and polishing
• Sandblasting
• Shot peening

This type of post-processing is extremely time-consuming and expensive, and especially with complex components, simply clamping the part securely in the machining centers can be a challenge. The achievable surface finish is also limited. Shot peening, while an effective smoothing process, typically achieves a roughness of still around 6-7 μm (Ra). Therefore, alternative post-processing methods are increasingly being tested, such as chemical/physical processes like laser polishing and electrochemical polishing. These methods promise lower labor costs and better smoothing results. Only electrochemical polishing allows access to internal surfaces within components. Support structures on or within complex geometries cannot be effectively removed using either conventional electropolishing or other methods. However, it is possible that component geometries can only be manufactured additively with high quality using such difficult-to-access support structures. Currently, such geometries often cannot be realized due to the described technical limitations of post-processing. The automated electrochemical post-processing method to be tested in this project is expected to largely eliminate or significantly reduce these limitations.

Project ongoing.

Interim results: The electrochemical post-processing system has been procured and commissioned. Basic parameters for the treatment of aluminum components have already been developed, and insights into average material removal rates have been gained.