Introduction to Injection Molding

Injection molding is the use of the thermophysical properties of plastic, the material from the hopper into the barrel, the outside of the barrel is heated by the heating ring, so that the material melt, in the barrel is equipped with external power motor driven by the rotating screw, the material under the action of the screw, along the screw groove forward and compaction, the material is gradually plasticized under the dual action of external heating and screw shear, melt and homogenization, when the screw rotation, the material in the screw groove Friction and shear force, the molten material has been pushed to the screw head, at the same time, the screw in the material under the counteraction back, so that the screw head to form a storage space to complete the plasticization process, and then, the screw in the injection cylinder piston thrust under the action of high-speed, high-pressure molten material in the storage chamber through the nozzle injection into the mold cavity, the molten material in the cavity after holding pressure, cooling, curing and shaping After the melt in the cavity is pressurized, cooled and cured, the mold is opened under the action of the mold closing mechanism, and the shaped product is ejected from the mold through the ejector device.

The injection molding machine is referred to as injection molding machine.

There are three types of injection molding machines: horizontal, vertical and angular, according to the configuration of the mold-closing and injection parts.

(1) Horizontal injection molding machine: Horizontal injection molding machine is the most commonly used type. It is characterized by the centerline of the injection assembly being concentric or consistent with the centerline of the molded assembly and parallel to the installation floor. It has the advantages of low center of gravity, smooth operation, easy installation, operation and maintenance of the mold, large mold opening gear, and small occupancy of space; however, it covers a large area, and is widely used in large, medium and small machines.

(2) Vertical injection molding machine: Its characteristic is that the axis of the mold closing device and the injection device are arranged in a line and perpendicular to the ground. It has the advantages of small footprint, convenient mold assembly and disassembly, easy installation of the insert, more uniform plasticization of the material falling into the hopper, easy automation and automatic line management of multiple machines, etc. The disadvantage is that the ejected products are not easy to fall off automatically and often need to be taken out manually or by other methods, so it is not easy to realize fully automatic operation and injection of large products; the machine body is high, and it is inconvenient to refill and maintain.

 (3) Angle type injection molding machine: The axes of injection unit and mold closing unit are arranged vertically to each other. According to the relative position of the center line of the injection assembly and the installation base, there are horizontal, vertical, vertical and horizontal: ① horizontal, the injection assembly line is parallel to the base, while the center line of the mold assembly is perpendicular to the base; ② vertical, the center line of the injection assembly is perpendicular to the base, while the center line of the mold assembly is parallel to the base. The advantage of angle type injection machine is that it has the advantages of both horizontal and vertical injection machines, and is especially suitable for molds with side gates for asymmetric geometry products.