Insufficient filling defects during injection molding

1. Insufficient resin capacity

Reason: The amount of resin injected into the mold is not enough to fill the entire mold chamber. Solution: increase the supply of resin to ensure that the maximum injection volume of Injection Molding Machine is greater than the total weight of plastic parts and water inlet. Longer the injection time to prevent the countercurrent of the resin before curing and difficult to fill the cavity.

2. Improper injection pressure or speed setting

Cause: The injection pressure or speed is too low, resulting in the melt material does not fully flow and fill in the type cavity. Solution: improve the injection pressure and speed to ensure that the melt can flow and fill in the cavity. Meanwhile, the injection pressure and speed setting are optimized according to the product shape and mold structure. Leave a certain buffer distance between the screw and the injection nozzle.

3. Improper setting of the resin temperature or the mold temperature

Reason: the resin temperature is too low, the viscosity increases, and the fluidity is reduced; the mold temperature is too low, and the melt material cooling is too fast, unable to fill the mold chamber. Solution: adjust the resin temperature and the mold temperature, and increase the mold temperature. Ensure that the melt material has sufficient liquidity. The resin temperature should not be too low to avoid excessive viscosity; the mold temperature should not be too low to avoid premature cooling of melt.

4. Poor mold exhaust

Reason: the mold exhaust system design is not reasonable or the exhaust channel is blocked, resulting in the gas can not be discharged smoothly, affecting the filling of the melting material. Solution: optimize the design of the mold exhaust system, add exhaust groove or exhaust hole, to ensure that the gas can be discharged smoothly. At the same time, regularly check and clean the mold exhaust system to prevent blockage.

5. Die design or manufacturing problems

Reason: gate or flow channel design is unreasonable, such as small size, insufficient quantity, resulting in melt flow blocked. Solution: improve the mold design, such as expanding the size of the gate or runner, the height of the gate should be equal to 1 / 2~1 / 3 of the wall thickness of the product, and the gate is set at the maximum wall thickness of the product. Increase the number of gates or passages to improve melt fluidity. At the same time, to ensure the manufacturing quality of the mold, to avoid the defects in the manufacturing process affecting the filling of the melt material. Set up exhaust tank (average depth 0.03mm, width 3 ~ smm) or exhaust rod. More important for smaller pieces.

6. Raw material problem

Reason: too many impurities in the raw material, or contain particles that are not easy to melt, which affect the fluidity and filling of the molten material. Solution: choose low viscosity and stable quality of raw materials, add lubricant, to ensure that the raw materials do not contain excessive impurities or not easy to melt particles. At the same time, the raw material is fully dried and pretreated to reduce the moisture and volatile content in the raw material.

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