Why does the injection mold have a dark color and poor gloss

Update: 27-08-2021

In the process of normal injection mold production and processing, the gloss of the mold surface is mainly determined by the type of plastic, the colorant and the finish of the mold surface. The main reasons and solutions for the dark color and poor gloss are as follows.
1. Poor finish of the injection mold, rust on the surface of the cavity, and poor mold exhaust.
2. Too much recycled materials are used, plastics or colorants are of poor quality, water vapor or other impurities are mixed, and lubricants used are of poor quality.
3. The gating system of the injection mold is defective, the cold slug well should be enlarged, the runner, polished main runner, runner and gate should be enlarged.
4. The material temperature and mold temperature are low, and local heating of the gate can be used if necessary.
5. Plastics must be fully plasticized, but to prevent degradation of the material, be stable when heated, and adequately cooled, especially for thick-walled ones.
6. The clamping force must be sufficient during the manufacturing process of the injection mold.
7. The processing pressure of the injection mold is too low, the speed is too slow, the injection time is insufficient, and the back pressure is insufficient, resulting in poor compactness and dark surface.
8. Prevent cold material from entering the part, use self-locking spring or lower nozzle temperature when necessary.

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