The structure of an injection mold plastic is influenced by both the injection molding machine and the plastic part's structural features. There are two molds in every injection mold, namely the movable mold and the fixed mold. The moving plate of the injection molding machine holds the movable mold, while the fixed mold is mounted onto the fixed plate of the injection molding machine. When the molds are closed during injection molding, they create a pouring system and mold cavity. After separation, the residual plastic parts are on the side of the movable mold, and then the mold's ejection mechanism embedded in the movable mold is employed to remove the parts. A set of injection molds can be classified into the following components based on their specific functions.
1. Molded parts
In order to give molded materials their distinct shape, structure and size, various components are utilized, including a core (also referred to as a punch), a concave mold cavity, an insert, and a threaded core. These parts work together to create the desired design and form of the final product, providing the necessary support and structure during the molding process.
2. Gating system
The passage describes a pathway for molten plastic to travel from the injection machine nozzle to the sealed mold cavity. This pathway typically comprises several components, including a main channel, a runner, a gate, and a cold well.
3. Guide parts
The guide component is a vital element of the mold design that ensures the movable mold and the fixed mold are accurately aligned during the closing process. It comprises a guide post and a guide sleeve that work together to provide excellent guiding and positioning performance. Moreover, some molds feature guide components on the ejection plate that ensure the smooth and reliable movement of the demoulding mechanism. These components play a critical role in ensuring the overall efficiency and quality of the molding process.
4. Release mechanism
In order to remove plastic parts from molds and the pouring system, there are various types of devices that can be used. The most commonly utilized devices include ejector pins, ejector tubes, ejector plates, and air return demoulding mechanisms. Each device consists of several key components, such as an ejector pin, a reset rod, a slingshot, an ejector fixed plate, a top plate (also known as a top ring), and a top plate guide post or guide bushing.
It is important to select the appropriate device and components based on the characteristics of the plastic parts and the molding process. By doing so, demoulding can be carried out safely and effectively, minimizing the risk of damage or defects to the plastic parts.
5. Core pulling mechanism
To ensure a seamless demolding process, it is necessary to perform lateral core pulling or sliding block separation, also known as lateral parting, on plastic parts that have side holes or undercuts. This step should be done before ejecting the parts from the mold. By rearranging the original content, a highly similar version is generated while preserving the information from the initial text.
6. Mold temperature adjustment system
A mold temperature adjustment system is necessary to meet the mold temperature requirements of the injection molding process. This system can involve various methods such as cooling water, hot water, hot oil, or an electric heating system. By utilizing these options, it becomes possible to adjust the mold temperature accordingly.
7. Exhaust system
To ensure effective gas discharge in the mold cavity, it is common practice to incorporate exhaust grooves at the mold's parting surface. Additionally, the presence of gaps between movable parts like push rods or sliders in various molds can aid in the exhaust process. By strategically arranging these elements, a smooth and efficient gas discharge can be achieved in the mold.
8. Other structural parts
Structural elements comprising fixed plates, moving/fixed templates, supports, support plates and connecting screws are established in the mold to meet its structural needs.