Author: MULAN -Plastic Molding Manufacturer
Color difference is a common defect in injection molding, and it is not uncommon for injection molding machines to be scrapped in batches due to color differences in matching parts. There are many factors affecting color difference, involving raw material resin, color masterbatch (or toner), mixing of color masterbatch and raw materials, injection molding process, injection molding machine, mold, etc. Because of the wide range of involvement, color difference control technology is also an important part of injection blow molding products. It is recognized as one of the more difficult techniques to master. As a brand custom manufacturer who often deals with injection blow molding products, here are some suggestions for controlling the color difference of injection blow molding products for your reference: In the actual production process, we generally control the color difference from the following six aspects: 1. Control the influence of injection molding machine and mold factors: It is necessary to choose an injection molding machine with the same capacity as the injection blow molding product. If the injection molding machine has problems such as material dead ends, try to replace the equipment. For the color difference caused by the mold gating system, exhaust groove, etc., it can be solved by repairing the corresponding part of the mold. It is necessary to solve the problem of injection molding machine and mold before organizing production, so as to reduce the complexity of the problem. 2. Eliminate the influence of raw material resin and color masterbatch: (1) Controlling raw materials is the key to a good solution to chromatic aberration. Especially when producing light-colored products, the influence of different thermal stability of raw material resins on product color fluctuations cannot be ignored. (2) Since most injection molding manufacturers do not produce plastic masterbatches or color masterbatches, they can focus on production management and raw material inspection. That is to strengthen the inspection of raw materials entering the warehouse; the same product should be produced by the same manufacturer, the same grade of masterbatch and color masterbatch as much as possible during production; (3) For the color masterbatch, we need to conduct spot checks and test colors before mass production. It must be proofread with the last time and compared with this time. If the color difference is not large, it can be considered qualified, just like a batch of color masterbatches with slight color difference , 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 focus on testing the thermal stability of raw resins and color masterbatches. For those with poor thermal stability, we recommend manufacturers to replace them. 3. Control the influence of uneven mixing of color masterbatch and masterbatch: (1) Poor mixing of plastic masterbatch and color masterbatch will also make the color of the product change. After the masterbatch and color masterbatch are mechanically mixed, when the material is fed into the hopper through the bottom suction, the color masterbatch is separated from the masterbatch due to static electricity, and it is easy to be adsorbed on the wall of the hopper. This will inevitably cause changes in the amount of color masterbatch during the injection molding cycle, resulting in chromatic aberration. (2) This situation can be solved by manually stirring the raw materials after being sucked into the hopper. For the production of colored products by adding toner, the effective way is not to use a suction machine, but to use a hot air dryer, and use manual feeding to prevent the color difference caused by the separation of toner and masterbatch. 4. Reduce the influence of barrel temperature on color difference: In production, it is often encountered that the temperature of the barrel changes sharply due to the failure of a certain heating ring or the out-of-control long-term burning of the heating control part, resulting in color difference. The color difference caused by such reasons is easy to judge. 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. 5. Reduce the impact of injection molding process adjustment: (1) When the injection molding process parameters need to be adjusted due to non-color difference, try not to change the injection temperature, back pressure, injection molding cycle and the amount of color masterbatch added. At the same time, it is necessary to observe the influence of the change of process parameters on the color. If the color difference is found, it should be adjusted in time . (2) Try to avoid the use of high injection speed, high back pressure and other injection molding processes that cause strong shearing effects, so as 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. 6. Master the influence of barrel temperature and masterbatch quantity on product color change: Before adjusting the color difference, it is also necessary to know the trend of product color change with temperature and color masterbatch amount. Different color masterbatch changes with the production temperature or the amount of color masterbatch, and the color change law of the product is different. Its change law can be determined through the color test process. A technical team proficient in blow molding with 23 years of experience, rich experience, strong ability to pre-control problems, strictly review drawings, assist in product deepening design, and make blow molded parts better in quality. It has its own mold opening production line, strong mold design and development capabilities, blow molding and injection molding can be customized, and there are thousands of existing molds, which can meet the needs of mold opening and customization in various fields. The technical team has successfully served tools/amusement/agricultural machinery/children's products/electrical appliances/medical and other fields, with more than 10,000 successful cases and trustworthy.