Lost foam casting accords with the general trend of casting technology development and has a broad development prospect. Its superiority is undeniable, but it has specific applications. So what are the main characteristics of lost foam casting?
The characteristic of lost foam casting is that it uses foam plastic that disappears when it encounters metal as a mold, no need to mold, no parting surface, no core, so the casting has no flash burr, which reduces the size error caused by the combination of the core.
The dimensional accuracy and surface roughness of castings are close to the level of investment precision casting.
Due to the use of dry sand, defects due to moisture, binders and additions are eradicated, the casting rejection rate is significantly reduced, and the casting quality is significantly improved. This process does not require high level of operation of workers and is very attractive to the foundry industry.
At low temperature, polystyrene (EPS) is completely harmless to the environment, and the organic matter discharged during pouring is also less. EPS organic matter emissions only account for 0.3% of the mass of the molten iron, while the self-hardening sand is 0.5%.
At the same time, the production time of organic emissions is short, the location is concentrated, and it is easy to collect. It can be treated by negative pressure suction combustion purification. After purification, the combustion products have no pollution to the environment, and the recycling rate of used sand is above 95%.
Compared with the traditional casting method, the lost foam aluminum casting method has significantly reduced noise, carbon monoxide gas and silica dust hazards, greatly reduced labor intensity of workers, significantly improved labor environment, and easy to achieve mechanized and automated clean production.
The components that were originally processed and assembled from multiple parts can be cast as a whole by the method of split molding and then bonding after using the EPC process, and the core can be omitted, and the holes can be directly cast, which greatly saves processing and assembly costs.
At the same time, the investment in processing equipment can also be reduced. Generally speaking, compared with the traditional casting process, the investment in lost foam casting technology equipment and casting costs can be reduced.
The flow front of the molten metal is the lost foam product (gas and liquid) of pyrolysis, which reacts with the molten metal and affects the filling of the molten metal.
If the pyrolytic products can not be eliminated smoothly in the process of metal filling, it is easy to cause defects such as porosity, wrinkled skin and carburization, which requires the technologist to master the principle of lost foam casting, correctly design the pouring system and formulate a reasonable process scheme.
The manufacturing cost of the mold is high, and a certain production batch is required, otherwise it is difficult to obtain good economic benefits.