Product color difference in plastic mold processing plants is a common defect in the injection molding process. It is not uncommon for injection molding machines to be scrapped in batches due to different colors of accessories. There are many factors affecting chromatic aberration, involving raw material resin, masterbatch, mixing of masterbatch and raw materials, injection molding products, injection molding machines, molds, etc., involving a wide range of fields, so chromatic aberration control skills are also recognized as one of the most difficult skills in injection molding. I'll go into more detail next.

1. Eliminate the influence of injection molding machine and mold components

To choose an injection molding machine with the same capacity as the main product of plastic mold processing, if the injection molding machine has problems such as material dead angles, the equipment should be replaced. For the color difference caused by the mold casting system, exhaust groove, etc., it can be solved by repairing the corresponding part of the mold. Before organizing production, the problem of injection molding machines and molds must be solved to reduce the complexity of the problem.

Eliminating the influence of raw resins and masterbatches and controlling raw materials is the key to solving color differences. Therefore, especially in the production of light-colored products, the significant impact of different thermal stability of raw material resins on product color fluctuations cannot be ignored. Given that most injection molding manufacturers do not produce plastic masterbatches or masterbatches themselves. In this way, the focus can be on production management and raw material inspection. That is, strengthen the incoming inspection of raw materials; In production, the same product should use masterbatches of the same manufacturer and the same trademark as much as possible. 1. Production of masterbatches; For masterbatches, we need to do spot checks and color trials before mass production. It must be compared with the previous calibration and this one. If the color difference is not large, it can be qualified, just as the batch masterbatch has a slight color difference, the masterbatch can be remixed before use to reduce the color difference caused by the uneven mixing of the masterbatch. Itself. At the same time, we also need to check the thermal stability of the raw resin and masterbatch. For poor thermal stability, it is recommended that the manufacturer switch.

2. Eliminate the influence of uneven mixing of masterbatch and masterbatch

Poor mixing of plastic masterbatches with masterbatches can also lead to changes in product color. After the masterbatch and masterbatch are mechanically mixed, when the material is sent into the hopper through the lower suction air, due to static electricity, the masterbatch and the masterbatch are separated, and it is easy to adsorb on the hopper wall, thereby separating the masterbatch from the masterbatch. This inevitably leads to changes in the amount of masterbatch used in the injection cycle, resulting in chromatic aberration. At this point, the raw materials can be sucked into the hopper and then manually mixed. Now many enterprises use the feeder to add color, which saves a lot of manpower and provides great help for color difference control, but many enterprises often fail to achieve satisfactory results because of improper use. The amount of masterbatch added to the feeder at a fixed speed depends on the plasticization time, and the plasticizing time itself fluctuates, sometimes the fluctuation is even relatively large, so to ensure a stable feeding volume, the feeding time of the feeder needs to be fixed, and the fixed time is less than the plasticizing time. When using the feeder, you should always pay attention to the fact that due to the small outlet of the feeder, after a period of use, the raw material powder accumulated in the feeder screw may cause the feeder to be blocked, or even cause the feeder to stop, so regular cleaning is required.

3. Reduce the influence of barrel temperature on color difference

In the production of plastic mold processing plants, it is often encountered that due to the failure of a heating ring or the long-term loss of control of the heating control part, the temperature of the barrel changes drastically, and then the color difference occurs. The chromatic aberration caused by this cause is easy to determine. Generally, the heating ring is damaged and fails. The occurrence of color difference will be accompanied by uneven plasticization, and the uncontrolled long-term combustion of the heating control part will often be accompanied by air spots, severe discoloration and even coking of the product. Therefore, the heating part needs to be checked frequently during the production process, and when it is found that the heating part is damaged or out of control, it is replaced and repaired in time to reduce the chance of such color difference.

4. Reduce the impact of injection molding process adjustment

When it is necessary to adjust the injection molding process parameters due to non-chromatic aberration, try not to change the injection temperature, back pressure, injection cycle and masterbatch addition. This adjustment also requires investigating the impact of changes in process parameters on Honor. If color difference is found, it should be adjusted in time. Try to avoid the injection molding process with high injection speed, high back pressure and other strong shear effects, and avoid chromatic differences caused by local overheating or thermal differentiation. Strictly control the temperature of each heating section of the barrel, especially the nozzle and the nozzle close to it. Heated part.

5. Master the influence of barrel temperature and masterbatch dosage on product color change

Before adjusting for chromatic aberration, it is necessary to understand the trend of product color with temperature and masterbatch usage. Different masterbatches change with the change of production temperature or masterbatch dosage, and the color change law of the product is different. Its change law can be determined by the color trial process. Unless you understand the color variation patterns of this masterbatch, you cannot quickly adjust the color difference, especially when selecting the color produced by a new masterbatch.