Dimensional and geometrical characterization of plastic powder bed fusion parts through computed tomography

Additive manufacturing (AM) can produce parts with undercut surfaces and inner structures, which makes it difficult or even impossible to measure from a dimensional metrology perspective. Powder bed fusion can produce complex and intricate geometric shapes that may be challenging with traditional manufacturing methods. X-ray computed tomography is a comprehensive 3D imaging technology that can generate a point cloud for dimensional measurement. In this research a selective laser sintering (SLS) process with Polyamide 12 material was investigated. During the experiments the effects of the orientation of the manufactured parts in the build chamber and the effectiveness of a compensation to reduce the distortion of the parts during the AM process were analysed. The dimensional characteristics measured by computed tomography were as follows: position, diameter and cylindricity of cylindrical features. As a result, the compensation and the orientation of the parts have significant effect on the position, diameter and cylindricity values.