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How to choose the right injection molding machine

Release time:

Aug 11,2021

In recent years, with the development of the resin chemical industry, the mold industry, and the machine automatic control component manufacturing industry, the application range of injection molded products has been widely promoted and popularized. As various modified plastics, engineering plastics and composite plastics are used more and more widely, the precision and complexity of plastic products are becoming higher and higher, and it is becoming more and more important to choose the right injection molding machine. 　　 1. Factors affecting the selection of injection molding machine: 　　The important factors that usually affect the selection of injection molding machines include product weight repeatability, mold opening position, cycle time, etc. Therefore, the following information must be collected or possessed before making a selection: 　　1. Product: size (length, width, height, wall thickness), net weight and total weight, etc. 　　2. Material: the ratio of raw materials or granulated materials and other materials and crushed materials. 　　 2. How to choose the model of injection molding machine 　　 After obtaining the above information, you can follow the steps below to select a suitable injection molding machine: 　　The model and series are determined by the product and plastic. When a customer chooses an injection molding machine, the first step is to determine the structure of the injection molding machine: vertical injection molding machine, angle injection molding machine, or horizontal injection molding machine according to the product's take-out direction and mold structure. There is little difference in the structure of the glue injection machines of the major manufacturers, and the structure difference is mainly in the clamping structure. 　　 Three, the choice of the clamping force of the injection molding machine: 　　The mold clamping is determined by the design structure of the product mold and the plastic to determine the "clamping force" tonnage. The clamping force is an important parameter of the injection molding machine. When the high-pressure plastic melt fills the cavity, a large expansion force is generated in the cavity, which causes the mold to expand along the parting surface. If mold expansion is not allowed, the injection molding machine must provide a force greater than this expansion force to lock the mold, otherwise it will cause overflow and runout. This force is the clamping force. If the clamping force is too large, it will not only increase the customer’s purchase cost, but also increase the wear of the mold and the difficulty of venting in the cavity, causing the product to burn or lack of material. More importantly, the machine will cause the machine to be stressed. Increased wear and tear shortens the life of the clamping mechanism and hydraulic system, and also wastes energy. Therefore, when calculating the clamping force, the customer’s product projection area and the ratio of the process length to the wall thickness, material, and mold cavity must be used to calculate the clamping force. Pressure is used to calculate the more accurate clamping force. The clamping force is the same as the injection volume, which reflects the ability of the machine to process the product to a certain extent, and is often used as the main parameter to indicate the size of the machine. 　　Four, select the appropriate injection molding machine according to the mold 　　1. Connecting pillars (also called guide pillars): The inner spacing determines the width of the mold's overall dimensions. The larger the inner distance of the guide pillars can accommodate larger molds, and the smaller the inner distance of the guide pillars can accommodate smaller molds. The minimum contact area between the mold and the template cannot be less than 60%, and the maximum effective area of the mold cannot exceed the area of the spacing between the connecting columns, otherwise the engine template will be unevenly stressed, the product will be partially flashed, and the template will be easy to crack. 　　2. Mold size: The template is a ductile iron plate supported on the back of the mold, and the mold should not exceed the inner distance of the template. To prevent the mold from bending during injection. If the mold is too small, it will generate excessive bending stress on the template, and even break the template. When injecting thin-walled products, the injection pressure is high, the injection speed is fast, and the cycle time is short. The template should be thickened, and the reinforcing ribs should be strengthened to increase the rigidity. 　　3. Modulus: The smallest to largest mold that the injection molding machine can accommodate. The difference between them is the modulus of the injection molding machine. The available mold thickness should be larger than the minimum modulus, so that the injection molding machine can open and lock the mold. Otherwise, add special engineering (the effective thread of t

　　 1. Factors affecting the selection of injection molding machine:

　　The important factors that usually affect the selection of injection molding machines include product weight repeatability, mold opening position, cycle time, etc. Therefore, the following information must be collected or possessed before making a selection:

　　1. Product: size (length, width, height, wall thickness), net weight and total weight, etc.

　　2. Material: the ratio of raw materials or granulated materials and other materials and crushed materials.

　　 2. How to choose the model of injection molding machine

　　 After obtaining the above information, you can follow the steps below to select a suitable injection molding machine:

　　The model and series are determined by the product and plastic. When a customer chooses an injection molding machine, the first step is to determine the structure of the injection molding machine: vertical injection molding machine, angle injection molding machine, or horizontal injection molding machine according to the product's take-out direction and mold structure. There is little difference in the structure of the glue injection machines of the major manufacturers, and the structure difference is mainly in the clamping structure.

　　 Three, the choice of the clamping force of the injection molding machine:

　　The mold clamping is determined by the design structure of the product mold and the plastic to determine the "clamping force" tonnage. The clamping force is an important parameter of the injection molding machine. When the high-pressure plastic melt fills the cavity, a large expansion force is generated in the cavity, which causes the mold to expand along the parting surface. If mold expansion is not allowed, the injection molding machine must provide a force greater than this expansion force to lock the mold, otherwise it will cause overflow and runout. This force is the clamping force.

If the clamping force is too large, it will not only increase the customer’s purchase cost, but also increase the wear of the mold and the difficulty of venting in the cavity, causing the product to burn or lack of material. More importantly, the machine will cause the machine to be stressed. Increased wear and tear shortens the life of the clamping mechanism and hydraulic system, and also wastes energy. Therefore, when calculating the clamping force, the customer’s product projection area and the ratio of the process length to the wall thickness, material, and mold cavity must be used to calculate the clamping force. Pressure is used to calculate the more accurate clamping force. The clamping force is the same as the injection volume, which reflects the ability of the machine to process the product to a certain extent, and is often used as the main parameter to indicate the size of the machine.

　　Four, select the appropriate injection molding machine according to the mold

　　1. Connecting pillars (also called guide pillars): The inner spacing determines the width of the mold's overall dimensions. The larger the inner distance of the guide pillars can accommodate larger molds, and the smaller the inner distance of the guide pillars can accommodate smaller molds. The minimum contact area between the mold and the template cannot be less than 60%, and the maximum effective area of the mold cannot exceed the area of the spacing between the connecting columns, otherwise the engine template will be unevenly stressed, the product will be partially flashed, and the template will be easy to crack.

　　2. Mold size: The template is a ductile iron plate supported on the back of the mold, and the mold should not exceed the inner distance of the template. To prevent the mold from bending during injection. If the mold is too small, it will generate excessive bending stress on the template, and even break the template. When injecting thin-walled products, the injection pressure is high, the injection speed is fast, and the cycle time is short. The template should be thickened, and the reinforcing ribs should be strengthened to increase the rigidity.

　　3. Modulus: The smallest to largest mold that the injection molding machine can accommodate. The difference between them is the modulus of the injection molding machine. The available mold thickness should be larger than the minimum modulus, so that the injection molding machine can open and lock the mold. Otherwise, add special engineering (the effective thread of the guide post increases, and the minimum value of the program needs to be changed). Also, when the available mold thickness is larger than the maximum modulus, special engineering is considered (the frame and the guide post and its threads are lengthened, the steel belt for the second plate of the frame clamping is lengthened, and the maximum value of the program needs to be changed.) But add The large capacity modulus has an upper limit, and the bearing capacity of the guide post (the bearing weight of the largest mold) should be considered. The maximum and minimum modulus of the dumpling-type injection molding machine are the distance between the movable and the fixed template when the dumpling is straightened and the mold is adjusted to the maximum and minimum. This parameter determines the size of the mold opening space and the product depth. The greater the modulus, the deeper the product depth; conversely, the shallower the product depth. The full-hydraulic large-scale two-platen injection molding machine has larger modulus and mold opening stroke than the dumpling injection molding machine of the same level, which is more suitable for deep cavity products and high-height products.