Study On Mechanism And Performance Of Large-size 3D Printing Based On Full-color 3DP Technic

3D printing is an intelligential,customized and automated technique based on the theory of additive manufacturing.In recent years,a large number of manufacturing industries and academic institutions have paid attention to 3D printing for its unique virtues including high precision,low consumption,Integrated molding etc.With innovation and improvement of the technique and demand of application industry,full-color large-size and high-precision 3D printing must be the development trend of 3D printing industry in the future.Powder-based3DP technic,one of the few full-color 3D printing,is potential to build large-size models superior to other full-color 3D printing technics in mechanical properties,cost of materials and printing speed.However,they restrict the feasibility of constructing full-color large-size3D printing model that lengthy printing process,unsatisfactory surface color reproduction accuracy and size limitation of 3D printing bin.Therefore,the experiments were carried out in view of the three restriction in this paper.In this paper,the structure and whole printing process of ProJet860 Pro powder-based printer were introduced in detail.Based on the moving characteristics of nozzles as well as fast axis in the forming process,the factors of digital models related to printing time were obtained,and the quantitative relations among Z-axial height,slice area and printing time were summed up to propose a time estimation algorithm before forming process.According to calculated influence factors of each factor,the xyx rotation method was proposed to reduce print time without changing the size of models.Based on the most effective post-processing,impregnation process,for optimizing the color of 3D printing surface,four impregnation combinations were set up to measure and compare the characteristics of color optimization on single or multi surface.Combined with the results of different impregnated surface structure characterization,the effects of structure difference on surface color reproduction were obtained to guide the improvement direction of impregnating methods and impregnants.Cutting-bonding frame(CBF)is a scanty method to build large-size model under the limited size of printing bin.Based on the method,the mechanical properties of powder-based 3D printing components conducted with different impregnation combinations and cutting angles were tested in this paper to select the best parameters to maximize the strength of parts before bonding process.The mechanical properties,gap width and surface chromatic aberration of powder-based components were compared to select the most suitable adhesive for powder-based 3D printing.Finally,a kind of realizable constructing process for full-color large-size powder-based 3D printing object was proposed.The results revealed that the highest weight in all relevant indicators for printing time is Z-axial height,XYX rotation method could effectively reduce the printing time.The printing time was maximally reduced by 65.7%in the verification experiment,so it would availably decrease for tens of hours by XYX rotation method when large-size objects were built.Along with the saturation of 3D printing surface color was greatly increased and the brightness was slightly decreased,the gamut was enlarged after impregnation process.ColorBond and transparent coating spray are the most suitable impregnation combination for powder-based3D printing,which greatly reduces the chromatic aberration of almost all colors(except a few high brightness colors),and also reduces the chromatic aberration between different surfaces.The improvement of surface color after impregnation process is closely related to the change of structure.Surface chromatic aberration shown a decreasing trend with the decrease of surface porosity as well as coating roughness and the increase of coating transparency.The mechanical strength of impregnated components was greatly increased by ColorBond,especially after the impregnated components were coated with two-component epoxy resin,but printing accuracy and surface color would be slightly changed.The best cutting angle is45°to z axis.When the quantity is controlled to 25 mg/cm~2,the mechanical property of bonded component can be as strong as that of uncut powder-based 3D object,and the surface chromatic aberration is almost imperceptible to human vision.