Types of injection molding

From Plastics Wiki, free encyclopedia

The are many types of injection molding.

Contents 1 Reaction injection molding 2 Liquid injection molding 3 Gas assist injection molding 4 Co-injection molding 5 2-Shot Injection Molding 6 Fusible core injection molding 7 Rapid injection molding

Reaction injection molding

Process for molding polyurethane, epoxy, and other liquid chemical systems. A mixture of two to four components in the proper chemical ratio is accomplished by a high-pressure impingement-type mixing head, from which the mixed material is delivered into the mold at low pressure, where it reacts (cures).

Liquid injection molding

Process that involves an integrated system for proportioning, mixing, and dispensing dual-component liquid resin formulations and directly injecting the resultant mix into a mold which is clamped under pressure. See Injection molding.

Gas assist injection molding

Plastic molding process in which a high-pressure gas is co-injected along with the plastic part to produce discrete internal hollow sections. It differs from blow molding in that one large hollow product is not created; rather, a solid piece with hollow sections is produced.

Co-injection molding

This is a process that creates a skin and core material arrangement in a molded part. The skin material is injected first into the mold cavity, and is immediately followed by a core material. As the skin material flows into the cavity, the material next to the cavity walls freezes and material flows down a center channel. When the core material enters it displaces the skin material in the center of the channel by pushing the skin ahead. As it flows ahead it continues to freeze on the walls producing the skin layer

2-Shot Injection Molding

This technology produces a part with two different raw materials or colors in a single operation. The machine has two injection units: one vertical and one horizontal. By using a rotating mold, the machine automatically produces a substrate of one resin or color and overmolds the part with the second resin or color.

Fusible core injection molding

It is used in the manufacture of molded components with cavities or undercuts, which would not be possible with tools having demoldable cores.

Rapid injection molding

Rapid Injection Molding allows us to make prototype injection molded parts in a production thermoplastic resin in 2-5 weeks. These parts may be used for full functional and fit testing as well as test marketing.