Effect Of Heat Dissipation Conditions On Processing Precision Of FDM And Surface Chemical Polishing Process

Fused Deposition Modeling(FDM)is one of the most widely used additive manufacturing technologies at home and abroad.With the rapid development of the technology,the demand of surface roughness become higher and higher.For this kind of manufacturing technology,temperature control is the basis,but the transient temperature distribution is difficult to control precisely during the forming process,which may lead to surface defects caused by insufficient heat dissipation.This article focuses on the influence of cooling conditions on the FDM precision.Furthermore,chemical polishing mechanism and technology have been studied in polishing material made from Poly Lactic Acid(PLA).The collapse and dislocation between two layers of FDM parts were closely related to the temperature changing process.Then,the main factors influencing the forming precision were summarized and the mechanisms for defects happened on the slope small cross section during molding process were also revealed.The contradictions of opposite demand for hot and cold of different parts area were indicated and the semiconductor refrigeration technology was applied in the forming process of cooling control,which was based on the analysis of the traditional temperature control scheme.The cold air made by semiconductor refrigeration system was acted on the small cross section of printing layer,and the hot end was applied to keep the formed parts under the suitable temperature.It is found that the method could avoid defects of large-slope small-cross section.At the same time,it could reduce the warping deformation of forming parts because of rapid cooling.The PLA was adopt to study chemical polishing processing of fused deposition molding parts.Then the polishing characteristics of different ways were analyzed.Furthermore the reaction mechanism of chemical polishing studied by model hypothesis and its validity was verified by experimental observation.The results show that the model established could reveal the change rule of dissolution and flow between adjacent layers on surface before and after polishing morphology.Also this study could be used to guide the optimization of polishing process.The effect of chemical polishing on tensile properties of FDM parts was studied.Experimental results show that horizontal molding directions have rarely impact on maximum tensile resistance of samples.And tensile performance of samples after chemical polishing has obvious changed,with tensile strength reduced dramatically and toughness improved.