How to control the color difference of plastic injection molding machine?Plastic injection molding machine processing should control color difference from five aspects: 1 Eliminate the influence of injection molding machine and mold factors. 2 Eliminate the influence of uneven mixing of masterbatch and masterbatch. 3 Reduce the influence of barrel temperature on color difference. 4 Reduce the impact of injection molding process adjustment. 5 Grasp the influence of the barrel temperature and the amount of masterbatch on the color change of the product.
1.Eliminate the influence of uneven mixing of masterbatch and masterbatch
Poor mixing of plastic masterbatch with color masterbatch will make the product color change impermanently. After the masterbatch and the color masterbatch are mechanically mixed and sent into the hopper through the lower suction, the color 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 color masterbatch to change during the injection cycle. Chromatic aberration. In this case, the raw materials can be sucked into the hopper and then manually stirred. Nowadays, many injection molding machine companies use feeders to add color masterbatch, which saves a lot of manpower and provides great help for color difference control. However, many companies often find it difficult to satisfy the results due to improper use. The amount of color masterbatch added by the feeder at a fixed speed depends on the plasticizing time, and the plasticizing time itself fluctuates, sometimes even relatively large, so to ensure a constant feeding amount, the feeding time of the feeder needs to be increased Fixed, and the set time is less than the minimum plasticizing time. Pay attention when using the feeder. Because the feeder has a small outlet, after a period of use, the raw material powder accumulated in the feeder screw in the injection molding machine may cause inaccurate feeding and even stop the feeder. Transfer, so it needs to be cleaned regularly.
2.Eliminate the influence of injection molding machine and mold factors
It is necessary to choose an injection molding machine with the same capacity as the main injection molding product. If the injection molding machine has problems such as material dead ends, it is best to replace the equipment. The chromatic aberration caused by the mold gating system and the exhaust groove can be solved by the maintenance mold of the corresponding part of the mold. The problem of injection molding machine and mold must be solved first before production can be organized to reduce the complexity of the problem.3.Reduce the influence of barrel temperature on color difference
In the production of injection molding plants, it is often encountered that a certain heating ring is damaged or failed or the heating control part is out of control and the temperature of the barrel changes drastically, resulting in color difference. The chromatic aberration caused by this kind of reason is easy to determine. Generally, the chromatic aberration caused by the failure of the heating ring will be accompanied by uneven plasticization. The out-of-control heating of the heating control part is often accompanied by product air spots, severe discoloration and even coking. Therefore, it is necessary to check the heating part frequently during production, and replace and repair it in time when the heating part is found to be damaged or out of control, so as to reduce the chance of such color difference.4.Reduce the impact of injection molding process adjustment
When the injection molding process parameters need to be adjusted for non-chromatic aberration reasons, do not change the injection temperature, back pressure, injection cycle, and the amount of masterbatch added as much as possible. The adjustment also needs to observe the effect of process parameter changes on the brilliance. If color aberration is found, it should be adjusted in time. Try to avoid the use of injection molding processes that cause strong shearing effects such as high injection speed and high back pressure to prevent color difference 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.5. Grasp the influence of barrel temperature and color masterbatch volume 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. With the change of the production temperature or the amount of color masterbatch, the color change law of the product is different. The color test process can be used to determine its changing law. Unless the color change law of this masterbatch is known, it is impossible to adjust the color difference quickly, especially when using new masterbatch production.
There are many factors that affect the color difference in injection molding, involving raw material resin, color masterbatch, mixing of color masterbatch and raw materials, injection products, injection molding machines
, molds, etc. Because of the wide range of involvement, color difference control technology is also recognized as one of the difficult technologies in injection molding. One.
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