Geometric Form Errors in Hollow Cylindrical Parts Manufactured by Powder Bed Fusion

Powder bed fusion (PBF) fabricated parts contain residual stresses and exhibit anisotropic mechanical properties due to rapid cooling rates and layered manufacturing. The residual stresses lead to part distortion. A stand-alone hollow cylindrical part may be preferred to be manufactured in a build orientation with its axis vertical to minimize geometric distortions. However, when the cylindrical hole or protrusion feature is only a part of a component of complex geometry governing the build orientation, the feature may have its axis in any direction. In the present work, the geometric form error, namely the cylindricity error, is investigated in a hollow cylindrical part with its axis perpendicular to the build direction. To reduce the residual stresses and homogenize the microstructure, necessary heat treatment is required. Numerical simulation is used to predict the distortions in the PBF fabricated parts and the effect of the heat treatment on them. This simulation helps to optimize the PBF process’s parameters and heat treatment cycle time. Necessary validatory experiments are conducted to verify the results of the simulation. A transient thermal model coupled with structural is used to predict the distortions of the PBF manufactured components. Geometric form errors of the hollow cylindrical components made by PBF with and without heat treatment are estimated using numerical and experimental techniques, and the results are compared.