In Fused Deposition Modeling (FDM) manufacture, adjustment of the object printing direction can improve the surface accuracy of the manufactured model, and can effectively reduce the printing time and printing material. However, the existing algorithm seldom takes account of all these factors. Considering these three factors and analyzing the people's subjective perception of the precision of the salient features and the damage caused by removal of the supporting, we propose the relationship functions among printing direction, support structure material, model surface printing supplies, printing time, model surface accuracy, salient features of precision and the processing cost of the model. According to these functions of the six evaluation indexes, the optimal printing direction objective function is constructed, and is solved to obtain the optimal printing direction. Experimental results show that the algorithm can be used to calculate the optimal printing direction of the object in various conditions, optimize the accuracy of the surface of the object, save the printing material and printing time, and avoid the damage caused by the post processing.
