Traditional Culture Encyclopedia - Traditional culture - Principle of physical foaming mold

Principle of physical foaming mold

Simply put, it is to foam plastics by physical means. There are usually three methods:

(1) Firstly, the inert gas is dissolved in the plastic melt or paste under pressure, and then the gas is released under reduced pressure to form pores in the plastic foam;

(2) foaming by evaporating the low boiling point liquid dissolved in the polymer melt;

(3) adding the hollow ball into the plastic to form foam for foaming.

The cost of physical foaming agent used in physical foaming method is relatively low, especially carbon dioxide and nitrogen, which are flame retardant to pentahydrate and have high application value; In addition, the physical foaming agent has no residue after foaming, which has little effect on the performance of the foaming mold. However, it requires special injection molding machines and auxiliary equipment, which is technically difficult. Chemical foaming method

Chemical foaming method is to foam plastics by using gas produced by chemical methods: heating the chemical foaming agent added to plastics to separate the gas and release foam; In addition, the gas released by the chemical reaction between various plastic parts can also be used for foaming.

The injection process of chemical foaming agent foaming mold is basically the same as the general injection process. The heating, mixing, plasticizing, foaming and expansion of plastics are all completed in the injection molding machine.

In a word, no matter which plastic raw material is selected and which foaming method is adopted, the foaming process generally goes through the stages of foam core formation, foam core expansion, foam body curing and molding.

Structural foaming molding

Structural foaming is a chemical foaming method and a revolution of injection molding technology. It retains many advantages of traditional injection molding technology and avoids the problems of insufficient product strength, long production cycle and low molding rate encountered by traditional injection molding technology.

In addition, structural foaming technology can also be used to mold large and complex products, and multiple cavities can be operated simultaneously with low-cost molds, thus reducing the production cost of products. Structural foamed product is a kind of conjoined foamed material with dense surface layer, and its strength and stiffness per unit weight are 3~4 times that of similar unfoamed materials.