# How to select the screw parts of injection molding machine

update:27-01-2021
abstract:

1. The relationship between the screw diameter of injec […]

1. The relationship between the screw diameter of injection molding machine and injection stroke the screw diameter of injection molding machine and the stroke interval of injection molding machine are the key to choose the quality and shape of injection products. The ratio of screw diameter to injection stroke interval should be in the range of 3 ~ 5 considering the satisfactory injection material quantity, plasticizing ability and injection pressure. Assuming that the ratio of the two is too large, it is clarified that when the stroke of the screw of the injection molding machine is too large, the length of the working part of the screw of the injection molding machine will be reduced, which will affect the plasticizing quality of the data. Assuming that the ratio is too small and the injection stroke of the screw of the injection molding machine is too small, the diameter of the screw of the injection molding machine must be increased in order to ensure the material consumption for one injection, so the screw operation of the injection molding machine consumes power addition, and it is difficult to ensure the accuracy of the feeding amount.

2. The screw spacing and rib width of injection molding machine the screw pitch of injection molding machine is generally equal to the diameter of injection molding machine screw, and the screw pitch of an injection molding machine screw is equal, when the thread rise angle is 17.8 °. Take e = 0.1D (D is the screw diameter of injection molding machine).
3. Equipment vacancy between screw and barrel of injection molding machine after screw of injection molding machine is installed into barrel, the interval between outer diameter of screw and inner diameter of barrel is radial vacancy. When this value is too large, the plasticizing quality and plasticizing ability of the data will decrease, and the flux of molten material will increase during injection, which will affect the accuracy of injection material quantity. Assuming that the radial vacancy is too small, it is difficult to add I to the screw and barrel of the injection molding machine. Generally, this value is (0.002-0.005) d (D is the screw diameter of the injection molding machine).

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