In recent years, with the development of the resin chemical industry, mould industry and automatic control machine manufacturing industry, the application range of injection moulded products has been widely promoted and popularised. As the application range of various modified plastics, engineering plastics, and composite plastics becomes more widely used, and the requirements for the precision and complexity of plastic products become higher and higher, the selection of suitable plastic moulding machine for sale becomes more and more important.
Factors influencing the choice of plastic moulding machine for sale
Usually, the important factors affecting the selection of the injection moulding machine are the weight repeatability of the product, the position of the mould opening, the cycle time, etc. Therefore, the following information must be collected or possessed before the selection is made:
- The product: size (length, width, height, wall thickness), net weight and total weight, etc.
- Materials: raw materials or granulated materials and other materials and the proportion of broken materials.
Injection molding machine how to choose the model
After determining the product information, you can follow the steps below to choose the right injection molding machine:
Machine types & series:
Decide the machine type and series according to the product and plastic. When the customer chooses the injection molding machine, the first thing to do is to determine the structural shape of the injection moulding machine according to the product take-out direction and mould structure: Vertical plastic injection molding machine, Angle moulding plastic machine, or Horizontal plastic moulding machine for sale. There is not much difference in the structural shape of molding machines from major manufacturers, and the structural difference is mainly in the mould clamping structure.
Wide range:
Due to the wide range of plastic molding machine, first of all, we should correctly judge which injection molding machine or series should be used to produce the product, such as ordinary thermoplastic or bakelite raw materials or PET raw materials, such as single-color, two-color, multi-color, sandwich or mixed-color. In addition, some products require high stability (closed loop), high precision, high injection speed, high injection pressure, or multi-loop (multi-circuit), and other conditions, it is also necessary to choose the appropriate series.
Selection of clamping force of the injection molding machine
Clamping is determined by the product mould design and construction and plastic to determine the “clamping force” tonnage. Clamping force is an important parameter of the injection molding machine, when the high pressure of the plastic melt is filled with the cavity, will produce a large expansion force in the cavity, so that the mould along the parting line expands. In order not to allow the mould to expand, the plastic moulding machine for sale must provide a force greater than this expansion force to lock the mould, otherwise, it will produce the phenomenon of overflow and runaway material, this force is the clamping force.
The clamping force is too large, not only will increase the customer’s purchase cost, but also will increase the wear of the mould and the cavity exhaust difficulty, so that the products will produce burnt or lack of material phenomenon; more importantly, when the machine is stressed, so that the machine wear intensified, shorten the life of the clamping mechanism and the hydraulic system, it will also cause a waste of energy, Therefore, when calculating the clamping force, we should use the projected area of the customer’s product and the ratio of process length to wall thickness, the material, and the cavity pressure of the mould to calculate the accurate clamping force. Clamping force and injection volume, to a certain extent, reflect the size of the machine’s ability to process products, which is often used as the main parameter to indicate the size of the machine specifications.
Choose the right type of injection moulding machine according to the mould
From the mould size to determine the machine’s “column pitch”, “mould thickness”, “mould size” and “mould plate size” is appropriate to confirm that the machine is suitable. To confirm whether the mould can be placed appropriately.
Connecting column (also known as guide column):
The internal distance determines the width of the external dimensions of the mould, the guide column can accommodate a large distance of the mould is also large, the guide column can accommodate a small distance of the mould is also small. Mould and template minimum contact area can not be less than 60%, and the maximum effective area of the mould can not exceed the area of the connecting column in the distance, otherwise easy to motor template force is not uniform, the product locally produced flying edge, the template is easy to crack.
Mould size:
The template is supported behind the mould ductile iron plate, the mould should not exceed the area of the template’s internal distance. To prevent the mould from bending during injection. Mould is too small and will produce too high bending stress on the template, and even make the template fracture. Injection of thin-walled products, high injection pressure, injection speed, cycle time is short, the template should be thickened, reinforced rib plate to strengthen, used to increase the rigidity.
Mould capacity:
The injection molding machine can accommodate the smallest to the largest mould, the difference between them is the moulding plastic machine mould adjustment. The available mould thickness should be greater than the minimum mould capacity so that the injection molding machine can open and close the mould. If this is not the case, special engineering work is required (the effective mould adjustment thread of the guide column is increased and the minimum value of the programme is changed). Similarly, if the available mould thickness is greater than the maximum mould capacity, special work is taken into account (the frame and the guide column and their threads are lengthened, the steel belt for moving the second plate of the frame clamp is lengthened and the maximum value of the programme is changed).
However, there is an upper limit for increasing the mould capacity and it is necessary to take into account the load capacity of the guide column (maximum mould load capacity). The maximum and minimum mould capacity of the machine dumpling type moulding plastic machine is the distance between the movable and fixed templates when the machine dumpling is straightened and the mould is set to the maximum and minimum respectively, this parameter determines the size of the mould opening space and the depth of the products. This parameter determines the size of the mould opening and the depth of the products. If the mould capacity is large, the depth of the products will be deeper; if the mould capacity is small, the depth of the products will be shallower. The fully hydraulic large two-platen moulding plastic machine has a larger mould capacity and mould opening stroke than other machines in the same class, which is more suitable for deep-cavity products and products with a high height.
