Research And Analysis On Mechanical Property And Quality For 3D Printing Workpiece Based On FDM Molding Technology

As one emerging adding material manufacturing technology, the 3D printing rapid proto-typing technology is developing and growing rapidly. At the same time, it is regarded as manufacturing technology which has significance of the industrial revolution. The 3D Printing is gradually sweeping the world with its unique advantages. Up to now, humans have successfully produced a number of products with the use of 3D printing technology. Nevertheless, there is a big problem and defect with the products quality molded by 3D printing. For example, the part mechanical properties are insufficient to meet the practical application. So, this thesis is aimed at researching and enhancing the mechanical properties of the workpiece and molding quality through improving 3D printing crafts based on fused deposition modeling technology.The specific work contents in this thesis is expounded as follows:(1) The mechanical property results of PLA and PA B330 material are analyze and presented through diagrams and tables respectively with the six processing parameters(printing temperature, fill density, vertical shells, layer height, fill angle and fill pattern). Finally, the influence effect of the change of each parameter on the mechanical property is investigated, and the best printing value of every parameter is obtained.(2) Comparing the variation tendency detailedly between PLA and PA B330 with the six processing parameters(printing temperature, fill density, vertical shells, layer height, fill angle and fill pattern). As for every parameter, the similarities and differences between the two materials are compared. And the inner reasons causing this differences are analyzing deeply. The results indicated that, the higher printing temperature, the larger ultimate strength of PLA and PA B330, however, the smaller Young modulus of PLA and the larger Young modulus of PA B330. The more vertical shells, the larger ultimate strength and Young modulus of PLA and PA B330, however, the smaller ultimate elongation. The lager layer height, the smaller ultimate strength and the lager Young modulus of PA B330, and it is not obvious to PLA. The fill density plays an important rule on mechanical property of the two materials, the higher fill density, the lager ultimate strength and Young modulus of them. When the fill angle changes from 0° to 45°, the ultimate strength of PA B330 becomes lager and Young modulus becomes smaller. The influence between rectilinear and honeycomb fill pattern of PLA and PA B330 is just opposite.(3) Setting up mathematical model and computing theory results. Nonrepresentational analytical model is established based on some certain assumptions, the specimen is divided into a lot of elements one by one, and every element is divided into four sections as well. The force of every section and the adhesive force between the neighboring beads are computed. Finally, the young’s modulus and ultimate strength of specimen are obtained.(4) Analysis and comparison between the experimental data and the results of the analytical model. Take the vertical shells and fill density as examples. The ultimate strength and young’s modulus with different vertical shells are computed and compared with experimental data respectively, and the conclusion that this mathematical model is suitable for simulating the elastic deformation stage in specimen tensile test is obtained. At the same time, as for the different fill density, the acreage covered by material in the cross section are computed, and the conclusion that the adhesive force between the neighboring beads is increasing with the increasing fill density is obtained.