Application Of Additive Manufacturing Technology In The Manufacturing Of Lost Foam Patterns

Lost foam casting can form complex high-precision castings,without the need for parting surfaces,sand cores,draft angles,etc.,which can simplify the casting production process to reduce production costs and improve labor productivity,etc.,and the production process can be pollution-free,in line with the current development direction of green casting.However,the preparation process of the foam pattern of the lost foam casting is complicated and requires pre-foaming and curing steps,which has the limitations of mutiple manufacturing cycles and long process.For different castings,different molds need to be designed during the production process,resulting in problems such as long manufacturing cycles,high production costs,large mold costs,and large storage space.In view of the above-mentioned production and processing problems of traditional lost foam casting foam patterns.In the paper,we use fused deposition modeling(Fused Deposition Modeling,FDM)technology to study and improve the traditional foam pattern manufacturing methods in lost foam casting.Finally verify the feasibility of the process through casting experiments.Firstly,FDM is one of the fastest manufacturing technologies with the lowest application cost.However,the molded parts of FDM technology are poor in terms of dimensional accuracy,surface roughness and mechanical properties.This paper has studied the main factors affecting the quality of the sample.The study focuses on the main influencing factors that restrict the quality of parts.The results show that: within the printing temperature range of PLA wire 190 ?-210 ?,when the printing temperature is 210?,the sample is completely formed,the surface is smooth and free of defects.The factors that have the greatest influence on the surface roughness of the sample are the layer thickness and the printing forming angle.When the layer thickness is 0.1mm,the sample surface roughness is the smallest,and the forming angle is 20° or 30°.Filling rate has no obvious effect on surface roughness.The factor that has the greatest impact on dimensional accuracy is the layer thickness,followed by the fill rate,and the smallest is the printing speed,but the printing speed will affect the forming integrity of the sample.The surface hardness of the FDM printed sample is in the range of 60HD-80 HD.The biggest influencing factor is the thickness of the top / bottom,and it increases with the increase of the thickness of the top / bottom.Secondly,this paper studies the influence of wall thickness,filling rate the top /bottom thicknessand other parameters on the mechanical properties of the sample.The research results show that when the filling rate is 0%-4%,the compressive strength of the sample increases with the wall thickness increase.At 25%-50%,the filling rate has the greatest impact on the compression properties of the sample.For the tensile properties of the sample,the top / bottom thickness is the most influential factor,followed by the wall thickness.Finally,the FDM printed mold was applied to lost foam casting and verified the feasibility of this process in lost foam casting.Based on the actual casting results of castings such as insufficient casting and surface carbonization,the reasons for these problems were analyzed,and some specific improvements were proposed,such as using traditional foam of the pouring system with materials replacing PLA materials,the cutting method at the end of the inner runner of the casting,and the use of the top-injection pouring system,etc.,which provided reference and suggestions for subsequent research.