What are the main components of an plastic injection mold?

Injection mold is a kind of mold that must be made before producing plastic products. Each plastic product design has its own mold. Injection molding refers to the injection of heated and melted plastic materials into the mold cavity at high pressure and high speed by an injection molding machine, and after cooling and solidification, a molded product is obtained.

Although the structure of the injection mold varies due to the type of plastic, performance, shape and structure of the plastic product, and the type of injection equipment, but the basic structure is the same.

The basic structure of the injection mold can be divided into seven parts: molding parts, gating system, guiding mechanism, ejector device, lateral parting and core pulling mechanism, cooling and heating system and exhaust system.

1, Molding parts

It refers to the parts that constitute the mold cavity, mainly including: punch, die, core, forming rod, forming ring and inserts and other parts.

2, Gating system

It refers to the plastic flow channel in the mold from the injection molding machine nozzle to the cavity, which ensures the appearance and internal quality of the plastic part, improves the molding speed and shortens the molding cycle. Ordinary gating system is composed of main runner, branch runner, gate, cold material hole and so on.

1) Definition of the main channel: The main channel refers to the section from the contact between the nozzle of the injection machine and the mold to the runner.

2) Definition of branch runner: the section between the main runner and the gate, it is the transition section where the molten plastic flows from the main runner into the cavity, and it is also the transition section in the gating system through the change of cross-sectional area and the plastic turning, which can make the plastic get smoothly

3) Gate definition: Gate is also called feed port or inner runner. It is the narrow part between the runner and the plastic part, also known as the shortest part of the gating system.

4) Cold material hole structure: The cold material hole is used to store the cold material head generated during the injection interval, to prevent the cold material from entering the cavity and affecting the quality of the plastic parts, and to enable the molten material to fill the cavity smoothly. The hole is also called the cold material well.

3, Guiding mechanism

In the plastic mold, the main function of the guiding mechanism is to guide, to ensure the normal closing and separation of the movable and fixed molds, to avoid the collision between the movable and fixed molds, and to ensure the accurate clamping of the movable and fixed molds. The mold will generate lateral pressure during molding, which will cause dislocation of the movable and fixed molds. Especially in large-scale, thin-walled plastic parts or molds with asymmetric shapes of plastic parts that require high injection molding accuracy, when the sides of the cavity and core are subject to greater pressure, it is easy to cause the cavity or core to be offset. In order to ensure the relative position accuracy of the movable and fixed molds during injection molding, and to prevent lateral displacement of the movable, fixed molds and molding parts; Both the movable and fixed molds must have a positioning structure, and their functions are as follows:

1) Positioning function: maintain a certain orientation between the movable and fixed molds when the mold is closed, and maintain the correct shape of the mold cavity after the mold is closed.

2) Guiding function: When the mold is closed, the movable mold is guided to close in sequence to prevent damage to the core and to bear a certain lateral force.

3) Bearing effect: The ejector plate is used for demoulding or the three-plate mold structure, and the guide post can bear the heavy load of the pusher plate and the fixed mold cavity plate.

4) The function of maintaining smooth movement: For the demolding mechanism of large and medium-sized molds, it has the function of keeping the movement of the mechanism flexible and stable.

4, The ejector device

It mainly plays the role of ejecting the parts from the mold, and is composed of ejector rod or ejector pipe or push plate, ejector plate, ejector pin fixing plate, reset rod and pulling rod.

The ejection mechanism of the injection mold is also called the demoulding mechanism. In each cycle of injection molding, the plastic part must be taken out from the mold cavity, and the mechanism that completes the action of taking out the plastic part is the ejector mechanism.

The main function has the following two points

• When the mold is opened, it ensures that the plastic parts and the pouring system condensate can be smoothly released from the mold without deformation; The mechanism resets correctly.
• After the plastic parts and condensate are taken out from the mold, make sure that the ejector mechanism is correctly reset when the mold is closed.

5, Lateral parting and core pulling mechanism

The function of the lateral parting and core-pulling mechanism is to release the lateral punch or extract the lateral core, which usually includes inclined guide posts, bent pins, inclined guide grooves, wedge blocks, inclined sliders, and inclined guides. slots, gear racks and other parts.

6, Cooling and heating system

It consists of cooling system (cooling water hole, cooling water tank, copper pipe) or heating system. The function is to adjust the temperature of the mold process, and the temperature of the mold directly affects the quality and efficiency of the molding of plastic parts.

Plastic parts with low melting point and good fluidity can be cooled to shorten the production cycle. For some plastics with poor fluidity, in order to improve the fluidity, the mold can be heated.

7, Exhaust system

Its function is to remove the gas in the cavity, which is mainly composed of exhaust grooves and matching gaps.

In some large plastic parts or plastic parts with a relatively large injection volume, the injection mold is closed because there is air in the mold cavity. In the injection plastic, the pressure generated inside the cavity is too large, which will cause some parts of the plastic part to be damaged. The effect of air pressure causes the incomplete plastic parts to be missing. At this time, exhaust devices should be made at these corresponding positions to facilitate the removal of air!

Guangzhou Yijiada Plastic Products Co., Ltd. is a professional plastic mold design and production factory, dedicated to the design, development and production of molds for plastic parts, plastic packaging containers, electronic products, household appliances, household products, industrial applications, agriculture, medical equipment and other products. For a long time, we have won unanimous praise from customers at home and abroad by providing customers with services of low price, good quality and fast delivery. You can contact us to inquire about mold opening and product production for your custom molds such as plastic mold products, plastic injection molding products, plastic blow molding products, etc.

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