The Research On 3D Printing Forming And Post Processing Of PS Powders

3D printing technology has exhibited widespread application in the fields of space flight&aviation,biomedicine,automobiles and ships,because of its many excellent properties,such as three dimensional modeling,light weighting,dieless forming,integration of complex parts,Job shop-Customization or personalization and short productive cycle.This research investigated on the post-processing reinforcement process of resin/fibre cloth with the complicated parts by selective laser sintering technology(SLS technology),which was brought forward to prepare these structural parts for practical engineering application.Based on the project finance of Shanghai Science and Technology Committee“Applied research of 3D printing technology in the ship’s model testing”,this article studied on the complicated parts printed successfully by SLS sintering technology with the amorphous polystyrene(PS)powder as raw materials,and investigated the effect of various influence factors on the performance of the structural parts and the reinforcement of resin/fibre cloth post-processing,such as epoxy resin,the type of curing agent,dosage of curing agent and diluent.In addition,various analytic technologies,e.g.,SEM(scanning electron microscopy)and DSC(differential scanning calorimetry),and mechanical properties testing were adopted to evaluate and compare the difference of microstructure and comprehensive performance for SLS sintering parts before and after post-processing,and the main results are as follows:(1)By comparison testing,the optimum process parameters of SLS sintering for PS powders obtained as follows:the laser power at 11 W,scanning speed of 2500 mm/s,scanning interval at 0.15 mm and a powder-bed depth on 0.2 mm under preheat temperature at 90℃.(2)Through evaluating and comparing the mechanical properties of post-processing parts in four types of epoxy resin curing system(E-51/5772 curing system,E-51/548curing system,E-51/593 curing system and E-51/651 curing system),it can conclude that the optimum curing agent is 651 epoxy curing agent,and the optimum dosage of 5749reactive diluter is 15%.In addition,the optimal choice E-51/651 curing system has the excellent enhanced performance for 3D printing parts of PS powders,and the tensile strength,bending strength and impact strength of parts after curing reaction are 22.81 MPa,3.67 kJ/m~2 and 37.81 MPa,respectively.Furthermore,it can be found that the new compound system with the introduction of 6350 flexible epoxy resin can significantly improve the impact strength and bending strength of post-processing 3D printing parts with these new resin systems,which reach to 4.61 kJ/m~2 and 43.00 MPa,respectively.However,the tensile strength reduces slightly to 22.21 MPa.(3)Comparing the 3D printing parts reinforced by post-processing of E51/651/6350curing system,the impact strength,bending strength and tensile strength of 3D printing parts reinforced by the post-processing of nylon fiber cloth synergistic epoxy resin have been improved 42%,46%and 21%,respectively.However,the impact strength,bending strength and tensile strength of 3D printing parts reinforced by the post-processing of carbon fiber cloth synergistic epoxy resin have been improved dramatically 151%,200%and 290%,and it can satisfy the engineering application requirement of various structural parts(such as the ship’s model parts).(4)To compare the SEM fracture morphology of 3D printing parts before and after fibre cloth collaborative epoxy resin post-processing,it can be concluded that the original irregular voids of pristine 3D printing parts have been fully filled of penetrated epoxy resin after epoxy resin post-processing.It is attributed to the synergistic effects between PS particles and epoxy resin through high adhesion performance of epoxy resin,which can form a new composite by bonding closely.In addition,the infiltrating effect has been better among epoxy resin and nylon fibre cloth or carbon fibre cloth.This article proposed a superior method for fiber cloth synergistic curing enhancement with epoxy resin to 3D printing parts,and it was a post-processing that through resin infiltrating in SLS printing parts and then bonding in the surface of printing parts with fibre cloth to enhance curing effects synergistically.Compare with common impregnation resin and permeability wax post-processing,it can better improve the strength and comprehensive performance of 3D printing parts.