Design for Additive Manufacturing

It is common for additive manufactured parts to show anisotropy in all mechanical properties, including strength, stiffness and fatigue life. This is caused by the intrinsic directionality of AM processes. When setting up parts for manufacture, often the designer will choose to orientate the parts to fit the most on a single run, or for surface finish. However, this orientation is critical to the structural performance of the design and should be considered from the concept stage of design development.

​The graph below shows that under a moderate 20MPa cyclic stress, the part will handle 1,000,000 cycles in the X direction but only 3,500 cycles in Z. Without considering the anisotropy as part of the design process the part will either fail early or weigh more than is required for the application.

It all starts with material characterisation at Engenuity’s on-site test lab. We test the 3 orthogonal axes, plus other angles to check our assumptions. Tests are repeated to ensure the validity of the results. This data is input into material cards for analysis software. During the analysis development we align the critical load paths with the strongest axis of the material and explore different concepts to realise the optimal geometry. The process is completed with a verification step – new parts are printed and go back to the test lab for component level testing.

Engenuity offers support for all stages of the design development process for additive manufactured parts. Including material selection and characterisation, producing the materials cards for analysis and component optimisation with our experienced team of engineers.