Prediction and optimization of dimensional accuracy of inclined structures fabricated by laser powder bed fusion

Abstract

In this paper, the dimensional accuracy of inclined structures formed through laser powder bed fusion (LPBF) was predicted by a developed theoretical model. The investigated dimension of an inclined structure in this study includes the dimensions in thickness direction and in length direction. The thickness direction is inclined to the substrate, while the length direction is parallel to the substrate. According to the model, the dimension in thickness direction is not only related to the track width and solidification shrinkage, but also to the stair effect and laser penetration effect. However, the dimension in length direction is only related to the track width and solidification shrinkage, and is hardly affected by the laser penetration effect. A batch of Ti6Al4V inclined samples was fabricated by LPBF to test this model. As a result, the experimental and predicted results correspond well. Furthermore, the effect of contour scanning strategy with different process parameters on the dimensional accuracy was assessed. The results show that the irregular contour scanning line is proved to be good for the dimensional accuracy in thickness direction, while the dimension in length direction is directly affected by the width of the contour scanning line. Finally, an optimization window of the process parameters for the contour scanning strategy is established. Under the optimal process parameters, the dimensional accuracy is improved.