Basic structure of injection mold

Basic structure of injection mold

The structure of the injection mold is determined by factors such as the form of the injection machine and the complexity of the part. Regardless of its complexity, all injection molds can be divided into two parts: the movable mold and the fixed mold. The fixed mold is mounted on the fixed template of the injection machine, and the movable mold is mounted on the moving template of the injection machine. During the injection, the molding cavity and the casting system are closed by the movable mold and the fixed mold, and the mold is separated when the mold is opened, and the plastic parts are taken out.

According to the role of each component on the injection mold, it can be subdivided into the following parts:

(1) Molded parts

Molded parts are parts that define the cavity in the specified and movable part. It usually consists of a mold punch (mold core), mold cavity, an insert, etc.

(2) Gating/Feeding system of injection mold

The gating system is the passage through which the molten plastic flows from the nozzle of the injection molding machine into the cavity of the mold. It consists of the mainfold, the branch runners, the gate and the cold material hole.

(3) Guide mechanism of injection mould

The guide mechanism is divided into two types: the guide mechanism between the movable mold and the fixed mold and the guide mechanism of the ejector mechanism. The former is to ensure that the movable mold and the fixed mold are accurately aligned when the mold is closed, so as to ensure the accuracy of the shape and size of the plastic part.

(4) Demolding mechanism of injection mold

A device for removing a plastic part from a mold when the mold is opened, which is also called an ejection mechanism. There are many structural forms, such as a ejector release mechanism, a push plate release mechanism, and a push tube release mechanism.

(5) Lateral parting and core-pulling mechanism

When a hole or boss having a concave-convex shape on the side of the plastic part is required, a lateral punch or core is required for molding. Before the mold is opened, the lateral punch or the lateral core must be taken out or withdrawn from the plastic part, and the plastic part can be demoulded smoothly. The mechanism that moves the lateral punch or the lateral core is called a lateral core pulling mechanism.

(6) Heating and Cooling System

In order to meet the mold temperature requirements of the injection molding process, the mold temperature must be controlled, so the mold is often provided with a cooling system and a heating element is installed inside or around the mold. The cooling system typically has a cooling water channel on the mold.

(7) Eject system of injection mold

In the injection molding process, in order to discharge the air in the cavity, it is often necessary to open an exhaust system, usually by purposely opening a plurality of grooves on the parting surface, or using a mold push rod. Or exhaust the gap between the core and the template. The displacement of small plastic parts is not large, so the parting surface can be directly used for venting without having to provide a separate venting groove.

(8) Other parts

such as parts used to fix and support molded parts or  parts to position and limit.

2019-04-09T12:25:18+00:00 April 9th, 2019|About mold making|