How to solve the problem of porosity in lost foam casting 1

Lost foam casting is a new process with almost no margin and molding, which can greatly reduce the cost of machining. Compared with traditional sand casting methods, it can reduce the machining time by 40% to 50%, but many users are lost foam casting. The stomatal problem is troubled, the editor of Luoyang Liu's Mold will give you a brief summary of the inspection method, so that you will never be troubled by the stomatal problem.

1. Select the appropriate model material

Copolymer foam is used as the model material. Since the copolymer is decomposed by zipper type, the degree of gasification at one time is high, the proportion of liquid phase is small, and small molecule gas is easy to overflow from the coating. The density of the white mold is as small as possible under the premise of ensuring the strength and smoothness to reduce the total amount of gas generation. The pouring system uses a hollow straight sprue and a filter to mechanically block the liquid alloy and adsorb the comb flow to make the filling. More stable.

2. Use of pouring system and insulation riser

The opening of the inner runner should be conducive to the smooth, stable and rapid filling of the alloy without forming a dead zone. At the top of the casting, an atmospheric pressure insulation riser is set up to collect slag and shrink into one body. The castings are solidified in sequence, and the gas, slag quality and gasification residues in the alloy are floated to the riser part, reducing the probability of generating air holes, slag holes and shrinkage holes. Practice has proved that the feeding effect of the pulp feeder and the floating bead feeder is better than that of the foam spherical feeder, and the feeder covering agent can be used comprehensively.