Dr Simon Altenburg adjusts the camera aperture on a laser beam melting device used for optical tomography.

Dr Simon Altenburg adjusts the camera aperture on a laser beam melting device used for optical tomography.

Source: BAM

Additive manufacturing methods enable complex components to be constructed and manufactured with precision and in a cost-efficient manner. This is particularly useful when parts are only needed in small amounts. However, as this technology is still relatively young, suitable methods for quality control during manufacturing have been lacking to date. Scientists at the Bundesanstalt für Materialforschung und -prüfung (BAM) are thus investigating the process: They are developing methods that can monitor whether any defects occur within the component during production. In this way, complex post-production quality testing and rejects can be minimised in the future. The manufacturing of components – for applications within aerospace and medical technology, for example – would become quicker and more cost-efficient as a result.

In its project ‘Process monitoring in additive manufacturing’ (ProMoAM), BAM is focusing on examining the manufacturing of components from metallic feedstock materials. Among these components, there are those produced by selective laser melting in a powder bed process. The questions that arise are, for example: do gas pores or cracks form? And if yes: what causes them and how can we stop these quality defects from emerging?

In order to tackle this issue, the project team is developing spectroscopic and non-destructive testing methods to monitor the manufacturing process. “As the components are manufactured in layers during the powder bed process, each layer forms the surface at some point along the manufacturing process.” explains project leader Dr Simon Altenburg. “We use this opportunity for so-called in-situ monitoring.” For this application, approaches such as thermographic and optical methods are used.

The individual measurement results are then merged to form a 3D data set which corresponds with the component’s geometry. The complete data set provides scientists with comprehensive information concerning the interior of the component, and therefore also its quality. In addition, conclusions can be drawn as to where the additive manufacturing process can be improved.

For their work, the project team uses BAM's extensive experience within the research-based and industry-oriented development of non-destructive and chemical analysis methods in industrial processes.
The quality of additively manufactured parts must be assured, particularly if they play an important role in the safe operation of industrial plants or engines. “Our goal is to monitor the production of components during the process in such a reliable way that no further tests are required following production in the future," says Altenburg.

Quality control while the process is ongoing will make the additive manufacturing of complex parts easier and quicker. It is in this way that BAM expertise is supporting the successful use of additive manufacturing processes in practice.

Where to find BAM at the Hannover Messe 2019

The main theme of BAM’s exhibition this year is additive manufacturing. Under the slogan "We add Safety to Additive Manufacturing" visitors will be able to gain insight into BAM's research in this area. BAM is also presenting its commitment to promoting spin-offs (stand C51 in the Research & Technology area in hall 2).

BAM will provide information on the quality assurance of offshore wind turbines in the same hall at the BMWi trade fair stand (hall 2, stand C28).

The publication "Additive Manufacturing at BAM - Safety in Focus" provides an overview of the wide range of our research in this area: www.bam.de/am-broschuere