How to control the color difference of products in the process of plastic mold processing

Author: MULAN – Plastic Molding Manufacturer

Product color difference in plastic mold processing plants is a common defect in injection molding. It is not uncommon for injection molding machines to be scrapped in batches due to different colors of matching parts. There are many factors affecting color difference, involving raw material resin, color masterbatch, mixing of color masterbatch and raw materials, injection molding products, injection molding machines, molds, etc. Because of the wide range of involvement, color difference control technology is also recognized as one of the most difficult skills in injection molding. Next, I will introduce it to you in detail.

1. To eliminate the influence of injection molding machine and mold elements, it is necessary to select an injection molding machine with an appropriate capacity for the main product of plastic mold processing. If the injection molding machine has problems such as material dead ends, replace the equipment. For the color difference caused by the mold pouring system, exhaust groove, etc., it can be solved through the repair mold of the corresponding part of the mold. It is necessary to solve the problems of injection molding machine and mold before the production can be arranged, so as to reduce the complexity of the problems.

Eliminate the influence of raw material resin and color masterbatch. Controlling raw materials is the key to solving color difference. Therefore, especially when producing light-colored products, the significant impact of different thermal stability of raw material resins on product color fluctuations cannot be ignored. Since most injection molding manufacturers do not produce plastic masterbatches or color masterbatches themselves, they can focus on production management and raw material inspection.

That is to strengthen the inspection of raw materials entering the warehouse; try to use the same manufacturer, the same trademark masterbatch, and color masterbatch for the same product in production; for color masterbatches, we need to conduct random inspections and test colors before mass production. In this comparison, if the color difference is not large, it can be qualified. It seems that the batch of color masterbatch has a slight color difference, and the color masterbatch can be re-mixed before use to reduce the color difference caused by uneven mixing of the color masterbatch itself. At the same time, we also need to check the thermal stability of the raw material resin and color masterbatch. For those with poor thermal stability, we recommend manufacturers to replace them. 2. Reduce the effect of barrel temperature on color difference. Plastic mold processing factories often encounter a damaged heating ring or a heating control part that is out of control and burns for a long time, resulting in drastic changes in barrel temperature and color difference.

The color difference caused by this kind of reason is easy to determine. Generally, the color difference caused by the damage and failure of the heating ring will be accompanied by uneven plasticization, and the uncontrolled long-term burning of the heating control part is often accompanied by gas spots, severe discoloration and even coking of the product. Therefore, it is necessary to check the heating part frequently during production, and replace and repair it in time when it is found that the heating part is damaged or out of control, so as to reduce the probability of such color difference.