An efficient scanning algorithm for improving accuracy based on minimising part warping in selected laser sintering process

Abstract

ABSTRACTIn the selective laser sintering (SLS) method, layers of powder are scanned by a laser beam and sintered. The thermal gradients created by laser heating and the subsequent cooling of the sintered sections results in thermal stresses and part warping in the final part. Thermal gradients are dependent on the scanning algorithm, in particular, the scan vector length. In this work, an efficient scanning algorithm for the SLS process is presented with the aim to minimise the part warping in the final part due to thermally induced residual stresses, while maintaining the production time at a minimum. The proposed algorithm is implemented in a finite element simulation and scanning parameters including the number of offsets and scanning length are optimised at constant laser parameters and chamber conditions. The FE model is verified by testing a few samples on SLS machine and comparing the parts made by the proposed algorithm with those made using conventional scan algorithm is the same as parallel-line scan algorithm. It is shown that part warping in the parts made by the proposed algorithm is reduced by up to 35% while the production time, part accuracy and surface properties are improved.