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Name：Rebecca Dong
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How do injection molds prevent streak defects? |
1. Meaning: the melt material enters the mold cavity and does not fill completely, causing the plastic parts to be missing.
Ii. Causes and elimination methods:
In the selection of equipment, the glue quantity of the machine should be greater than that of the product, and the weight of the injection molded parts can only account for 85% of the total amount of glue in the machine.
2.It is not sufficient for the feeding: whether there is a "bridging" phenomenon in the feeding port, it can increase the feeding amount of the screw injection.
Illiquid (3), raw materials, improve the mold stagnation defects of gating system, setting up reasonable pouring position, expand the sprue, runner and note the size and the larger nozzle, appropriate increase temperature of raw materials.
(4), gating system design is not reasonable, gating system design, pay attention to the runner balance, the weight of the molded parts within the cavity is proportional to the size of the gate, is the cavity can be filled at the same time, the gate location to choose in thick wall place, also can use points balance runner layout design.
(5), mold venting is not good: for cold chamber, or position is correct, for mould cavity is deeper, should be in the area of owe note add exhaust grooves and vent, to open on the surface of the clamping deep 0.02 0.04 mm, width is 5-11 mm vent groove, vent eventually filling type should be set in the cavity. Moreover in terms of process operation, can improve by mold temperature, reduce the injection velocity, pouring system reduce the resistance, and reduce the clamping force.
6.The mold temperature is too low: the mould must be preheated to the required temperature before starting the machine. If the mold temperature cannot rise, it is reasonable to check the design of the mold watercourse.
7.All landowners, inadequate injection pressure, injection pressure and the length of the die are close to direct ratio relation, the injection pressure is too small, mould filling, short length to fill, can shoot by slowing down the material speed and extend injection time to enhance injection pressure.
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Down：Solution of 15 common problems in mold maintenance and repair work.
Up：The principle of plastic injection mould. |
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