The structure of the injection mould is determined by factors such as the form of the injection moulding machine and the complexity of the parts. Regardless of its complexity, all injection moulds can be divided into two modes: movable mould and fixed mould. The fixed mould is installed on the fixed plate of the injection machine, while the movable mould is installed on the movable plate. During injecting, the movable and fixed moulds close the cavity and the gating system, and then open the moulds , separate the fixed and movable moulds, and take the parts out at last.
According to the role of each component on the scientific molding process, it can be subdivided into the following parts:
1. Forming parts of injection mould
Forming parts refer to the parts that make up the cavity of the fixed and movable moulds. Usually, it consists of punch (or core), die, insert and etc.
2. The gating system of injection mould
The gating system is the channel through which resin plastic flows from the injection moulding machine and goes into the cavity. It consists of the main runner, the branch runner, gate and the cold well.
3. The guiding mechanism of injection mould
The guiding mechanism can be divided into two categories: the one between the movable mould and the fixed mould and the one of the ejector mechanism. The former is to ensure that the movable mould and the fixed mould are accurately connected when the mould is closed, so as to ensure the precision of the shape and size of the parts.
4. Ejection mechanism of injection mould
The device used to eject the plastic parts from the mould when the mould is opened, also known as the ejector mechanism. It has a variety of structures. But the common ones are ejector pin, ejector plate and ejector tube.
5. Side-parting and core-pulling mechanism of injection mould
When there are bumps and holes or lug bosses on the side of the parts, a punch or core is required to form the shape. Before opening the mould and pushing parts out, the side punch or core must be pulled out or ejected from the parts, so that the plastic parts can be ejected smoothly. The mechanism that help move the side punch or core is called the side-parting and core-pulling mechanism.
6. Heating and cooling system of injection mould
In order to meet the temperature requirements of the precision moulding and moulds, the temperature of the injection mould must be under controlled. In that case, a cooling system is often equipped, and heating devices are installed in or around the mould. The cooling system usually is realized by setting up cooling waterways on the mould.
7. Exhaust system of injection mould
In order to discharge the air in the cavity during injection, to set up an exhaust system is of necessity. Generally, a number of air vents are purposely opened on the parting surface. Besides, gaps created by the pins, plates and tubes of the mould can be used to exhaust. Due to its small exhaust volume, the small parting surface can be directly used to exhausted air without air vents.
8. Other components of injection mould
Components used to fix and support the shaped parts as well as those play the role of positioning and limiting.