An injection molding machine, often abbreviated as an injection machine, is a key device in the plastics processing industry.

An injection molding machine, often abbreviated as an injection machine, is a key device in the plastics processing industry. The following is a detailed introduction to it:

Structure

• Injection Unit: It consists of a hopper, barrel, screw, and nozzle. The hopper is for loading plastic raw materials. The barrel, heated by heating coils, melts the materials. Driven by a motor, the screw rotates to convey, compress, and plasticize the materials in the barrel. The molten material is pushed to the screw head and then injected into the mold cavity through the nozzle.

• Clamping Unit: This unit is responsible for clamping and opening the mold. It mainly includes a fixed platen, a moving platen, and a clamping mechanism. The clamping mechanism generates the clamping force to hold the mold firmly during injection to prevent the mold from opening due to the pressure of the molten plastic.

• Hydraulic System: It provides power for the movement of each part of the injection molding machine, such as the injection, clamping, and ejection actions. It consists of components like oil pumps, valves, and oil cylinders. The hydraulic system can precisely control the pressure, flow rate, and direction of the oil to achieve accurate control of the movement speed and force of each part.

• Electrical Control System: It is the "brain" of the injection molding machine, which controls the entire injection molding process. It includes a programmable logic controller (PLC), human-machine interface (HMI), sensors, and various control circuits. The PLC receives signals from sensors and controls the operation of motors, solenoid valves, and other components according to pre-set programs and parameters.

Working Principle

• Plasticizing: Plastic pellets are added from the hopper into the barrel. The barrel heats the materials, and the screw rotates to shear and mix them, gradually melting and homogenizing the materials to form a molten state, completing the plasticizing process.

• Injection: After plasticizing, the screw, under the thrust of the injection cylinder piston, injects the molten material in the material storage chamber into the mold cavity at high speed and pressure through the nozzle.

• Cooling and Solidification: The molten material in the mold cavity is cooled and solidified into the shape of the mold cavity. The cooling time depends on factors such as the type of plastic, the thickness of the part, and the cooling efficiency of the mold.

• Ejection: Once the plastic part is cooled and solidified, the mold opens, and the ejection system, consisting of ejector pins and an ejector plate, pushes the plastic part out of the mold cavity.

Types

• Horizontal Injection Molding Machine: The center lines of the injection unit and the clamping unit of this type of machine are concentric or coincide, and they are parallel to the installation surface. It has the advantages of low center of gravity, stable operation, convenient mold installation, operation, and maintenance, large mold opening, and small occupied space height, but it takes up a large area.

• Vertical Injection Molding Machine: The axis lines of its clamping device and injection device are arranged perpendicular to the ground. It has the advantages of small floor space, convenient assembly and disassembly of insert molds, and even plasticization of materials from the hopper. It is easy to realize automation and automatic line management of the machine. However, the finished products are not easy to fall off automatically and it is not easy to realize full automatic operation and injection of large products.

• Angle Type Injection Molding Machine: The injection device and the molding device of this machine have their axes arranged at an angle. According to the relative positions of the injection unit's center line and the vertical and horizontal directions, it can be divided into horizontal-vertical and vertical-horizontal types.

Applications

Injection molding machines are widely used in various industries. In the automotive industry, they are used to produce bumpers, dashboards, door interiors and other parts. In the electronics industry, they are used to manufacture shells of electronic products such as mobile phones, computers, and TVs. In the daily necessities industry, they are used to produce plastic chairs, tables, basins, and other products.