Discussion on the possible factors of black spot discoloration in injection mold

    Injection molding machine mold, I believe we all know, is mainly a tool for the production of plastic products; In the manufacturing process of general injection molds, we often encounter some common problems, such as black spots, or discoloration and coking of injection products. However, the main reason for these problems is that the injection products stay in the barrel for too long, which leads to the decomposition and coking of injection products and the formation of injection cavity with molten materials. What are the possible factors of black spot discoloration in the injection mold of the injection molding machine? Next, the servo energy-saving injection molding machine will share with you!

    Servo energy saving injection molding machine

    1. Machine:

    (1) Because the heating control system on the machine fails to operate, it leads to overheating in the barrel, resulting in decomposition and blackening.

    (2) Due to the defects of screw and barrel, the molten material is stuck and accumulated, and the plastic is decomposed after long-time fixing and heating on the machine. At this time, the staff need to check whether the rubber head kit is worn and whether there are metal foreign matters in it.

    (3) When some plastics almost maintain the original particle shape, especially in the barrel, they will be cross-linked and coking due to high heat. These plastics are difficult to melt, so that they are finally crushed by the screw and entrained into the parts.

    2. Mold:

    (1) In general, if the exhaust of the mold is not smooth, it is also easy to scorch. In addition, the size of the gating system of the mold is too small or the cutting is too severe, resulting in coking.

    (2) Black spots will also appear when appropriate oil lubricants and release agents are used in the mold.

    3. Plastics:

    Plastic has too much volatiles, too high humidity, too many impurities, too many recycled materials and is polluted.

    4. Processing:

    (1) Too much pressure, too high speed, too much back pressure and too fast speed will decompose the material temperature.

    (2) The barrel shall be cleaned regularly to remove additives that are less resistant than plastics.