Increasing Productivity with X-Ray Systems Quality Management of Additively Manufactured Components Used in Formula 1

| Author / Editor: Gabriele Mäurer / Isabell Page

3D printing is becoming more and more relevant and widespread, especially when it comes to lightweight components in automotive or aerospace. Quality assurance for safety-crucial parts is of utmost significance. Thanks to X-ray and CT technology, even the smallest faults in 3D printed parts can reliably be detected and evaluated.

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This image shows the anodized aluminum oil pump housing as an additive component produced for Formula 1.
This image shows the anodized aluminum oil pump housing as an additive component produced for Formula 1.
(Source: Yxlon)

Additive manufacturing is particularly suitable for the production of small series, small quantities, prototypes or spare parts. With 3D printing, complicated designs can be produced that are extremely difficult or very expensive to produce as cast parts. In addition to plastics and (light) metals, hybrid materials are also suitable. Nowadays, the use of additive manufacturing in mass production is still comparatively expensive, but it also has a lot of long-term potential.

An important criterion for the manufacturing of additive components is quality assurance, which is particularly important for safety-relevant parts such as those used in the automotive and aviation industries. Typical errors in the 3D printing process include blowholes and bonding defects between layers. In addition, powder residues, contaminations, inclusions or distortions on the printed parts can impair the quality.

The use of industrial X-ray technology, i.e. digital X-ray and computer tomography (CT), provides additional information and offers decisive advantages in the detection of defects. Even with complex components, CT can be used to precisely determine external and internal structures. This information is essential, especially for prototype qualification.

CT for Additively Manufactured Formula 1 Components

3D printing is playing an increasingly important role, especially in lightweight design. In the following, three additive components for Formula 1 - from an anodized aluminum oil pump housing, a plastic air intake diffuser to a titanium hydraulic component - will be presented and analyzed by means of CT.

The first example of the anodized aluminum oil pump housing shows how beneficial the use of computer tomography is. The anodized coating provides a very hard and scratch-resistant surface to withstand the particularly high stresses during a Formula 1 race. At that time, the housing was considered acceptable by the optical appearance assessment. The CT scan (radiography of the rotating component with a 225kV X-ray tube, reconstruction of the digital 3D volume, and incorporation of a virtual cutting axis through the component) revealed two cracks that were not visible through the coating. With the help of CT, the oil pump housing could be identified as a faulty component.

The CT scan revealed two cracks that were not visible through the coating.
The CT scan revealed two cracks that were not visible through the coating.
(Source: Yxlon)

The use of computer tomography also proved to be advantageous for the plastic air intake diffuser. In a material analysis, two different diffusers with different material mixtures were examined for pores and inclusions. In the analysis, diffuser 1 made of heat-resistant polyamide showed isolated pores with a size of 1.1 m³ up to 0.04 m³. The second diffuser showed a uniform distribution of inclusions in the component (size 0.034 m³ to 0.3 m³), which were introduced specifically to change the material properties and, for example, to increase the strength of the component. The subsequent target/ actual comparison serves to prove the reproducibility of the parts. The CAD design drawing is superimposed with the measured values (CT volume file) and deviations are displayed in color. The comparison of both diffusers shows the red and violet areas as deviations from the tolerance values, while green areas meet the standard. The target/ actual comparison by means of CT is particularly useful for the measurement of internal structures, as this is currently not possible with other non-destructive measurement methods.

The CT can also provide valuable information on the 3D printing process when examining the wall thickness of a titanium hydraulic component. The pipe diameters along the longitudinal direction and at the rounded ends were examined. While the wall thicknesses in the longitudinal area are within the tolerance, the round area shows deviations, i.e. irregular diameters and insufficient wall thicknesses (up to -0.1 mm). The following questions arise: What influence does the 3D printing direction have on the wall thickness? Is the flow behavior impaired by walls that are too thin? Do very thin walls lead to cracks or fractures under high stress? These questions would possibly not have arisen without the use of computer tomography. One thing is for sure: In order to answer these questions, further investigations must be carried out.

CT - A Useful Tool for Quality Control of Printed Parts

Computer tomography allows a view into the interior of the additively manufactured components. With virtual sections of the 3D volume, the detected defects can be displayed directly in a three-dimensional space. Apart from the representation of specific additive manufacturing defects, such as powder residues, inclusions or delaminations, internal structures can be measured and deviations from the standard can be highlighted. In addition, conclusions about the 3D printing process can be drawn.