The color difference of products in the injection molding plant is a common defect in injection molding. It is not uncommon for the injection molding machine to be scrapped in batches due to the color difference of the supporting parts. There are many factors affecting color difference, including raw resin, color masterbatch, mixing of color masterbatch with raw materials, injection products, injection molding machines, molds, etc. Because of the wide range of involved, color difference control technology is also recognized as one of the more difficult technologies in injection molding. In the actual production process, we generally control the color difference from the following six aspects.

Eliminate the influence of injection molding machine and mold factors:
To choose an injection molding machine with the same capacity as the main product of the injection molding, if the injection molding machine has problems such as material dead ends, it is best to replace the equipment. For the color difference caused by the mold pouring system and the exhaust groove, it can be solved by the maintenance mold of the corresponding part of the mold. The problems of the injection molding machine and the mold must be solved before the production can be organized to reduce the complexity of the problem.

Eliminate the influence of raw resin and color masterbatch Control of raw materials is the key to completely solve the color difference. Therefore, especially in the production of light-colored products, the obvious influence of the difference in thermal stability of the raw material resins on the luster of the products cannot be ignored. Since most injection molding manufacturers do not produce plastic masterbatches or masterbatches themselves, the focus of attention can be placed on production management and raw material inspection. That is to strengthen the inspection of raw materials into the warehouse; the same product in production is produced using the same manufacturer, the same brand masterbatch, masterbatch as far as possible; for the masterbatch, we must conduct a random test and color test before mass production, both with the last proofreading, and In this comparison, if the color difference is not large, it can be qualified, as if the batch masterbatch has a slight color difference, the color masterbatch can be re-mixed before use to reduce the color difference caused by the uneven mixing of the color masterbatch itself. At the same time, we also need to focus on testing the thermal stability of the raw resin and color masterbatch. For those with poor thermal stability, we recommend the manufacturer to exchange them.

Eliminate the effect of uneven mixing of masterbatch and masterbatch:
Poor mixing of plastic masterbatch and color masterbatch can also make the color of the product volatile. After the masterbatch and the masterbatch are mechanically mixed and fed into the hopper through the lower suction, the masterbatch is separated from the masterbatch due to static electricity and is easily adsorbed on the hopper wall. This will inevitably cause the amount of masterbatch to change during the injection cycle, resulting in Color difference. This situation can be solved by sucking the raw materials into the hopper and then manually mixing them. Many companies now use feeders to add masterbatch, which saves a lot of manpower and provides great help for color difference control, but many companies are often difficult to satisfy the results due to improper use. The amount of masterbatch added to the feeder at a fixed speed depends on the plasticizing time, and the plasticizing time itself fluctuates, and sometimes the fluctuation is even large, so to ensure a constant amount of feed, the feeder's feeding time needs to be added Fixed, and the set time is less than the minimum plasticizing time. Please pay attention when using the feeder, because the feeder outlet is small, after a period of time, the material powder accumulated in the feeder screw may cause inaccurate cutting, or even cause the feeder to stop, so Need to be cleaned regularly.

Reduce the effect of barrel temperature on color difference:
In the production of injection molding plants, it is often encountered that the temperature of the barrel changes drastically due to the failure of a heating ring or the uncontrolled long-burning of the heating control part, resulting in color difference. The color difference caused by this kind of reason is easy to determine. Generally, the color difference caused by the failure of the heating ring will be accompanied by uneven plasticization, and the uncontrolled long burning of the heating control part is often accompanied by product gas spots, severe discoloration and even coking. Therefore, it is necessary to check the heating part frequently during production and replace and repair the heating part in time when it is found to be damaged or out of control, so as to reduce the probability of such color difference.

Reduce the impact of injection molding process adjustment:
When it is necessary to adjust the injection molding process parameters for non-color difference reasons, try not to change the injection temperature, back pressure, injection cycle and the amount of color masterbatch as much as possible. At the same time, it is necessary to observe the effect of the process parameter changes on the luster. If the color difference is found, it should be adjusted in time. As far as possible, avoid the use of high injection speed, high back pressure and other injection molding processes that cause strong shearing to prevent color differences caused by local overheating or thermal decomposition. Strictly control the temperature of each heating section of the barrel, especially the nozzle and the heating part close to the nozzle.

Grasp the influence of barrel temperature and color masterbatch on product color changes:
Before adjusting the color difference, you must also know the trend of the product color with temperature and the amount of color masterbatch. Different color masterbatch varies with the production temperature or the amount of color masterbatch. The color change process can be determined through the color test process. Unless you already know the color change rule of this masterbatch, it is impossible to adjust the color difference quickly, especially when using new masterbatch toning.