More than just time savings Automated reworking of 3D-printed parts

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Fotec Research and Technology Transfer at the University of Applied Sciences Wiener Neustadt has succeeded in making the reworking of additively manufactured components more economical with the help of a process known as ‘Hirtising’.

Fotec Research and Technology Transfer, the research company of the University of Applied Sciences Wiener Neustadt, has developed essential elements for the integration of additive manufacturing into industrial process chains as part of the international joint project ‘Ad-Proc-Add II’. The focus was on automated post-processing using Hirtising. This is a combination of chemical, dynamic electrochemical and hydrodynamic processes that does not require mechanical processing. Hirtising, which is based on liquid media, also treats deep cavities and undercuts on printed components. This means that support structures can also be removed. Many components can be Hirtised simultaneously in the machines.

Hirtising has been further developed

A highlight of Fotec’s contribution, it goes on to say, was the further development of Hirtising. Building on the results of a previous project, targeted machining strategies were developed for materials such as Ti6Al4V and 1.4404 (stainless steel). By adjusting the PBF-LBM process parameters (PBF: powder bed fusion; LBM: laser beam melting), machining allowances of only 180 to 550 micrometres could be defined. This is considered an important step towards material-saving, automated post-processing of 3D-printed parts. At the same time, surface roughness values of Ra ≤ 5 micrometres were achieved, enabling precise functionalisation of such components. The project also pursued the characterisation of additively manufactured surfaces and the development of databases for process optimisation.

Surface investigations and data management

Fotec conducted extensive investigations into the surface integrity of additively manufactured components. The aim was to analyse how different PBF process parameters, build orientations and intermediate treatments affect the final surface properties. A particular focus was placed on the interaction with processes such as shot peening (blasting), heat treatment and CNC form grinding. The resulting surface matrix provides a sound basis for the targeted combination and optimisation of additive and subtractive process steps.

As emphasised, a significant contribution to digital consistency in this area was the development of a cross-process data management system, which was created in the current project by the Institute for Manufacturing Technology and Photonic Technologies at TU Wien in collaboration with project partners. A prototype hybrid CAM system was supplied with multi-sensor-supported real-time data, which was used to automatically generate tool paths. The integration of sensor technology, material data and geometry information has enabled the development of an ‘intelligent’, adaptive CAM control system, which represents a milestone in the automation of complex ASM (additive-subtractive manufacturing) process chains.

Practical results through research funding

The Fotec results were characterised by a high degree of application orientation. During the course of the project, test specimens and use cases were manufactured and analysed from materials such as Ti64, 316L and AlSi10Mg. Close cooperation with the 15 industrial partners — including companies from the aerospace, toolmaking and medical technology sectors — ensured that the processes developed can be directly transferred to real manufacturing scenarios, according to the project team.

The project, funded by the Austrian Research Promotion Agency (FFG), the German Federal Ministry for Economic Affairs and Climate Action (BMWK) and the Flanders Agency for Innovation & Entrepreneurship (Vlaio) — coordinated by the ecoplus Mechatronics Cluster, FKM and KU Leuven — aimed to make additive-subtractive manufacturing chains economically viable, even for small and medium-sized enterprises (SMEs). Fotec acted as a leading player in the field of laser powder bed fusion (PBF-LB/M) and electrochemical and mechanical post-processing.

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