1. During the processing of raw materials, there are some black spots in the raw materials;
2. Black spots caused by impure granulation;
3. The raw material is mixed with color masterbatch or speckled crushed pieces and scraps;
4. The material is impure, and high melting pellets are mixed into the low melting point material;
5. Impurities may be mixed in during packaging, transportation, and storage. The obvious feature is that after the raw materials are opened, carefully observe that there are foreign bodies and impurities on the surface of the material particles;
6. Except for 5, which will not directly pollute the hopper material, other may pollute the raw materials during the feeding process, causing black spots and impurities in plastic products. Pollution sources include dust in the air, suspended solids, foreign material scraps, foreign material pellets, powdered color masterbatches, colorants, etc. In order to prevent black spots caused by foreign matter and impurities, management must be strengthened to control all links (including the recycling process) from the raw material entering the factory to the feeding.
When changing materials, you must carefully clean up the parts where the original materials or chips may stay, especially the material storage box, hopper, funnel, hem clamp fastening, etc. During normal production, pay special attention to the cleaning of the feed source-the the preparation box. After stopping production, seal the feeding port of the feeding pipe where the feeding system is exposed to the external environment to prevent contamination, and achieve interlocking and closed management.
7. The raw material is carbonized. This kind of black spots is generally larger in volume, and the appearance diameter of large black spots can reach 1-2mm. Most of the “black spots” are thicker, and there are one or two layers of thinner. In this case, the raw materials are accumulated for a long time or locally subjected to high heat, decomposed, coked, and carbonized into agglomerates. The flow is formed by shearing and breaking in the screw or nozzle. ,
Dongguan H.D.Plastics Products specializes in the production of extruded (extruded) plastic profile extrusion products. We can customize and process a variety of plastic profiles, PVC profiles, abs profiles, pp profiles, PC lampshades, transparent plastic profiles, and other profiles. Self-built mold room, specializing in providing solutions for all kinds of profiled materials with more than 10 years of experience in designing extrusion dies processing as well.