Compared with traditional sand casting, lost foam casting has many advantages. Its advantages are as follows:
(1) High dimensional accuracy of castings
Lost foam casting process, the casting is formed at one time. Because it does not need to take the shape as in sand casting, nor does it need to have parting surface and sand core, the produced castings have no dimensional deviation, burr, flash and draft angle. It is a forming process with high dimensional shape accuracy and surface finish.
(2) It has high production efficiency
Because there is no need for sand mixing and sand mixing in the traditional sand mold casting process, the molding cycle is short; When molding, there is no parting surface and sand core, which not only simplifies the process, but also reduces the operations such as box splitting, box closing, core lowering and mold turnover, but also realizes the pouring of multiple parts in one box. Therefore, for those castings with large production batch and complex geometry, this advantage is more prominent.
(3) The freedom of product design is large
The lost foam casting can improve the overall performance of the product, because the foam pattern can be used for subsequent bonding process to make the parts with complicated geometry can be produced at once by using lost foam casting process. Moreover, lost foam casting does not need parting surface and sand core, which also increases the design freedom of products with complex shapes.
(4) So that cleaner production can be realized
We know that some foam plastics can be foamed at low temperature and no harm to the environment. The filling of molten metal causes the combustion of foam pattern to decompose, the amount of gas generated by decomposition is short, the emission time is short, and it is easier to burn and purify, and the product after purification has no harm to the environment. Because the lost foam casting mold uses negative pressure to compact dry sand, the labor intensity of cleaning falling sand is reduced, and the recovery rate of old sand is also very high, which makes the working environment of the foundry industry better improved.
(5) The casting quality is improved and the scrap rate is reduced
Due to the advantages that lost foam casting does not need parting surface and mold taking, defects such as wrong box, burr and flash can be avoided. Moreover, lost foam casting uses dry sand and does not need to use binder, moisture and various additives like ordinary sand casting, which also reduces the defects of castings. Moreover, vacuum negative pressure pouring is used in lost foam casting, which improves the density of casting structure, because the negative pressure improves the mold filling ability and feeding ability of liquid metal.
(6) Wide applicability
Lost foam castings are suitable not only for cast iron and steel castings, but also for aluminum and copper castings; In terms of casting shape, castings with simple geometry and castings with complex geometry are applicable. Of course, there are many advantages of lost foam casting, but it also has its limitations. Compared with the traditional sand casting, lost foam casting eliminates the process of core making and core lowering, but lost foam casting has one more design and manufacture of foam forming mold, and it takes a long time; Moreover, the internal sprue size of lost foam casting is large, which leads to the complexity of cleaning; Moreover, the reaction of metal liquid and foam pattern reduces the temperature of the front of metal liquid, which reduces the fluidity of molten metal and affects the quality of castings. Because of the low strength, the foam pattern tends to deform in the process of compaction of dry sand, which leads to the deviation of casting shape.