Structural Composition And Function Of Injection Mould

I. Definition of injection mold

The mold used for plastic injection molding is called injection molding mold, or injection mold for short. The injection molding mold can be used to mold plastic products with complex shape, high dimensional accuracy or with inserts at one time.

"Seven points of mold, three points of process". For the injection molding process, the mold and the injection molding machine have a great influence on the quality of the molded products, and it can even be said that the mold plays a greater role than the injection molding machine; if you do not fully understand the mold when injection molding, it is difficult to get excellent molded products.

II. The structure of the injection mold

The structure of the injection mold is determined by the type of plastic injection molding machine and the structural characteristics of the plastic parts. When the mold is separated, the plastic parts or beer parts are left on one side of the moving mold, and then the plastic parts are ejected by the mold release mechanism set in the moving mold. According to the different roles of each part in the mold, a set of injection mold can be divided into the following parts.

1. Molding parts

The parts that give shape, structure and size to the molded material, usually consist of core (convex mold), concave cavity and threaded core, insert, etc.

2. Pouring system

It is the channel that leads the molten plastic from the injector nozzle to the closed mold cavity, usually consisting of main flow channel, diversion channel, gate and cold material well.

3. Guiding parts

In order to ensure the accurate alignment of the moving mold and the fixed mold closure, the guiding parts are set up to play the role of guiding and positioning, it is composed of guide pillar and guide bush, some molds also set up guiding parts on the ejector plate to ensure the smooth and reliable movement of the demolding mechanism.

4. Demoulding mechanism

The device to realize the demoulding of plastic parts and casting system, its structure is in many forms, the most common ones are ejector pin, ejector tube, ejector plate and pneumatic ejector and other demoulding mechanism, generally composed of ejector bar, reset bar, slingshot, ejector bar fixed plate, ejector plate (ejector ring) and ejector plate guide pillar/guide bush, etc.

5. Mold temperature adjustment system

In order to meet the requirements of injection molding process on the mold temperature, there is a mold temperature adjustment system heating rod to adjust the mold temperature.

6. Exhaust system

In order to discharge the gas in the mold cavity smoothly, often in the mold parting surface and the set of inserts to open the exhaust slot.

7. Other structural parts

It refers to the parts set up to meet the structural requirements of the mold (such as: fixed plate, moving / fixed template, support column, support plate and connecting screws, etc.).

III. The structure of the injection mold classification

1. According to the classification of molding method:

(1) injection mold: the mold used on the injection machine. Mainly used for molding thermoplastics, a few varieties of thermosetting plastics are suitable for the mold molding.

(2) Compression mold: It is a mold that uses compression process on hydraulic press to mold plastic parts. It is mainly used for molding thermosetting plastics.

(3) Pressure injection mold: the mold that adopts the pressure injection process on the hydraulic press to mold plastic parts. It is suitable for molding thermosetting plastics.

2. Classified by the number of cavities:

(1) Single cavity mold

It is a mold with only one cavity, molding one plastic part at a time.

(2) Multi-cavity mold

It is a mold with two or more cavities, which can mold multiple parts in one mold.