How to control the color difference of injection molding machine products?

1、 Eliminating the impact of injection molding machines and mold elements
Choose an injection molding machine with the same capacity as the primary injection molding product. If the injection molding machine encounters issues such as data dead corners, it is better to replace the equipment. The color difference caused by the gating system and the mold exhaust slot can be solved by repairing the mold at the corresponding part of the mold; Before organizing production, it is necessary to solve the problems of injection molding machines and molds to reduce the complexity of the problem.
2、 Reduce the impact of injection molding process adjustments
When adjusting injection molding process parameters due to non color difference reasons, try not to change the injection temperature, back pressure, injection cycle, and masterbatch dosage as much as possible. At the same time, it is necessary to observe the impact of changes in process parameters on color; If color difference is found, it should be adjusted in a timely manner.
Try to avoid using injection molding processes with high injection speed and high back pressure to form strong shear effects, and prevent local overheating or thermal decomposition to form color differences. Strictly control the temperature of each heating section of the barrel, especially the temperature of the nozzle and the heating part near the nozzle.
3、 The effect of reducing barrel temperature on color difference
In production, it is often encountered that due to damage or failure of the heating ring or uncontrolled burning of heating control components for a long time, the temperature of the material barrel changes sharply, resulting in color difference. The color difference caused by this reason is easy to distinguish; Generally speaking, the color difference caused by damage and failure of the heating ring will be accompanied by uneven plasticization.
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However, the heating control part that is out of control during long-term incineration is often accompanied by gas spots, severe discoloration, and even product coking. Therefore, during production, heating elements should be frequently checked. If the heating element is damaged or out of control, it should be replaced and repaired in a timely manner to reduce the occurrence of this color difference.
4、 Eliminating the impact of raw material resins and masterbatches
The manipulation of raw materials is the key to completely solving color differences, therefore, especially in the production of light colored products, the significant impact of different thermal stability of resin materials on product color fluctuations cannot be ignored. Given that most injection molding manufacturers do not produce plastic masterbatches or color masterbatches, they can pay attention to production management and raw material inspection.
Strengthen the storage and viewing of raw materials; Try to use color masterbatches from the same manufacturer and injection molding machine brand as much as possible to produce the same products; Regarding the color masterbatch, sampling and color testing should be conducted before mass production, and compared with the previous and current batch. If the color difference is not significant, it can be considered qualified, just like the color master batch has a slight color difference.
To reduce the color difference caused by uneven mixing of the masterbatch itself, we can mix the masterbatch from the beginning and then use it again. At the same time, we also need to test the thermal stability of the material resin and color masterbatch. Regarding products with poor thermal stability, we recommend manufacturers to replace them.
5、 Master the influence of barrel temperature and masterbatch on product color changes
Before adjusting the color difference, we also need to understand the trend of color changes in injection molding machine products with temperature and color masterbatch; As the production temperature or masterbatch dosage changes, the color change rules of the product also vary; Changing the rules can be confirmed through a color test process; It is impossible to quickly adjust the color difference unless you know the rules for changing the color of the masterbatch.