Statistical prediction of post-processing effort to repair dimensional inaccuracy of support-less horizontal holes in additively manufactured components for assemblability

A distorted horizontal circular hole on vertical walls, which is used for mechanical joint with a bolt, must be repaired in the post-processing. Therefore, it is important to estimate the post-processing effort in the design for additive manufacturing (DfAM) using laser powder bed fusion technique. Using gate-shaped specimens, the dimensional inaccuracy was measured. To calculate the removal volume, probable distorted shapes were generated with the help of discrete Fourier transform by extrapolating the statistically measured data. It was found that the proposed peripheral support that was inserted aside the horizontal holes could reduce the dimensional inaccuracy and post-processing effort. The material-type dependency was another important topic in this study. Three materials with different densities were studied. They were aluminum alloy, pure titanium and maraging steel. The highest post-processing effort was needed for light-weight aluminum alloy. The influence of hole diameter and wall thickness on the dimensional inaccuracy and the post-processing effort was also investigated. It was found that the larger sized holes on thicker vertical walls needed higher post-processing effort.