The basic principle of fusible core injection molding is to first cast a fusible core using a low melting point alloy, then put the fusible core into the mold as an insert for injection molding, remove the part containing the core from the cavity after cooling, and then heat the core to melt it to form a hollow product.
When injection molding plastic parts that are structurally difficult to release from the mold, such as automobile oil pipes and intake and exhaust manifolds, and other hollow products with complex shapes, fusible core injection molding can be used.
The process of fusible core injection molding technology is as follows.
Casting the core with low melting point metal → putting it into the mold for injection → taking out the part with the core → heating and melting the core → cleaning the part → product.
At present, the fusible core injection molding technology
only in PA66 has accumulated some experience, preliminary experimental research shows that PA6, PBT, PET, PPO, etc. are also suitable for fusible core injection molding.
The fusible core materials often used are Sn-Bi and Sn-Pb low melting point alloys. Melting cores are generally heated by oil and induction coils.
The advantages of fusible core injection molding are
1, especially suitable for the production of complex shape, hollow, not suitable for mechanical processing of composite products.
2、 Precise internal dimensions and smooth surface of hollow plastic parts, which cannot be achieved by usual methods.
3、 Compared with blow molding and gas-assisted injection molding
, although the equipment for casting fusible cores and melting cores have to be increased, the existing injection molding machines
can be fully utilized, and the freedom of molding is larger.
Notes on melt core injection molding process.
1. The core cannot be melted when the plastic part is injected.
2. The molten metal for the core and the medium used to melt the core will not corrode the plastic.
3、 Under the temperature of the melting core, the part will not be deformed.