According to the size of the clamping force, the injection molding machine can be divided into large, medium and small machines. The clamping force is measured in tons (or kN). Mold locking force refers to the locking force applied to the mold by the injection molding machine to overcome the expanding force of the melt in the mold cavity during injection. The production of small products uses a machine with a smaller clamping force, while the production of large products requires a machine with a larger clamping force. According to Ebang machine, the general minicomputer refers to the tonnage below 100 tons, the medium-sized machine refers to 100-500 tons, and the large machine refers to the injection molding machine of more than 500 tons. In addition, according to the plasticization method of the material, the injection molding machine can be divided into screw reciprocating, plunger type, screw pre-plastic plunger injection molding machine. According to the arrangement of injection device and clamping device can be divided into vertical, horizontal, Angle injection molding machine, the most widely used is the horizontal screw reciprocating injection molding machine.

Taking hydraulic toggle screw reciprocating injection molding machine as an example, its main composition is: injection, mold locking, hydraulic, electrical, fuselage, door and window parts and other 6 modules, of which injection, mold locking, hydraulic, electrical injection molding machine as the main components.

The main function of the injection part is to make the plastic uniformly plasticized into a molten state, and to inject a certain amount of molten material into the mold cavity with sufficient pressure and speed to achieve the function of measuring the plasticization of the processed plastic and ejecting the molten material. The injection device is generally composed of a plasticizing component (barrel, screw, nozzle, etc.), an injection cylinder, and a whole transfer cylinder. The clamping part is one of the important parts of injection molding machine, its function is to realize the opening and closing movement of the mold, make it close to produce the clamping force, and lock the mold. The traditional mode-locking component is composed of front, middle and back three plates, while the new mode-locking component is composed of front and back two plates.

The role of the hydraulic parts is to provide power for the various actions required by the injection molding machine according to the process, and to meet the requirements of the pressure and speed required by the action of the injection molding machine, so as to achieve the conversion and transfer of energy required in the molding process. The oil pump and the motor are the power source of the injection molding machine. Injection molding machine from the beginning of the closing mold to the end of the opening mold, the middle through a number of action flow. Each program has different requirements for pressure and speed, that is, at different times or different positions in the action, the flow and pressure are instantaneous and multistage changes, so the sensitivity, reliability, silence and safety of the injection molding machine hydraulic system and its components are very high requirements. The electrical components, that is, the control system, is the "nerve center" system of the injection molding machine, which controls various program actions to achieve the control and adjustment of time, position, pressure, speed, etc., so as to achieve the function of setting and controlling the working procedures and process conditions. The quality of the electrical components, that is, the control system, will directly affect the molding quality of the product, such as the control of the mold locking speed, low pressure mold protection, and mold locking force, which will affect the molding cycle of the product, low pressure mold protection, mold opening positioning, etc. At present, "mainframes of the second board, minicomputer electric" has become the main theme of the development of the industry, prompting injection molding equipment to energy-saving, high-precision and rapid prototyping development. With the development of related technologies and the improvement of injection molding equipment requirements for injection molding production processes, the research and development and industrialization of electric drive systems, large two-plate injection molding technology and multi-component injection molding technology continue to promote the development of the industry to high-end.