Research On Accuracy And Mechanical Property For Fused Deposition Modeling Part

Fused deposition modeling(FDM) process is one of the rapid prototyping technology most widely used at home and abroad. Nowadays, it plays an increasingly important role in the manufacturing industry. In the FDM process, the accuracy and mechanical property of molded part will be directly affected by the choice of the process parameters, which affects the scope of application of this technology. Bearing the above observations in mind, on the basis of theoretical analysis, through a lot of experimental investigations, the processing parameters would be configurated optimally in order to improve the accuracy and mechanical property of FDM part. The main works are illustrated in the following aspects:(1) The formation mechanisms and main influence factors for the Principle errors, manufacturability errors and the post-processing errors have been analyzed systematically. And then, the theories foundations and instructional criteria will be provided for subsequent processing experimental research.(2) The surface roughness and dimensional accuracy of the molded part are selected as the accuracy criteria in this thesis. A theoretical model of the surface roughness of molded part is established. Based on this model, a series of experiments have been done in order to investigate the effect laws of molding orientation and layer thickness on the surface roughness of FDM part. A compensation model of the width of ideal contour line for PLA filament on the molding orientation is established; on the basis of this model, a series of experiments has been done to study the effect laws of molding orientation on the dimensional accuracy of FDM part.(3) Taking the distortion of FDM Part for research object, the equivalent relationship between temperature load and mechanical load can be obtained. A theoretical model based on the theory of elastic thin plates in thermo elasticity is established. And then, the effect laws of several process parameters on the distortion are analyzed. On the basis of theoretical analysis, a special specimen is designed and a orthogonal experiment with five factors and three levels has been implemented. By using of analytic method of statistics, the effect laws and degree of the selected process parameters can be achieved. Moreover, the optimal process parameters minimizing the part distortion can be obtained.(4) Using tensile strength, bending strength and impact strength as evaluation indexes characterizes the mechanical property of FDM part. Three groups of orthogonal experiment with five factors and three levels have been designed and implemented. Two statistical analysis methods, Signal-to-noise ratio(S/N) and Analysis of Variance(ANOVA) are applied to reveal the effect laws of several process parameters on the three evaluation indexes. Three sets of optimal process parameters could be get to optimize each evaluation index. Based on the grey relating analysis method and the results of orthogonal experiment, a multi-objective optimization model for the mechanical property of FDM part is established to seek out the combination of process parameters making the mechanical property of FDM part optimally.