How to control the color difference of injection molding machine screw products
In the actual production process, we generally control the color difference from the following five aspects. The specific methods are as follows:
1, eliminate the impact of injection molding machine and mold elements
It is best to replace the equipment if it is necessary to select an injection molding machine with the right capacity for the injection molding. If there is a problem such as a dead space of the injection molding machine screw. Regarding the mold casting system, the venting grooves and the like forming chromatic aberration can be processed by the repairing mold of the corresponding part of the mold. It is necessary to first deal with the problem of injection molding machines and molds in order to organize production to reduce the complexity of the problem.
2, eliminate the influence of material resin, color masterbatch
Controlling raw materials is the key to completely solving chromatic aberrations. Therefore, especially in the production of light-colored articles, it is not negligible that the thermal stability of the resin of the material has a significant influence on the fluctuation of the color of the product. Since most injection molding manufacturers do not produce plastic masterbatch or color masterbatch themselves, the focus can be on production management and raw material inspection.
That is to strengthen the inspection of raw materials into the warehouse; the same product in the production should use the same manufacturer as much as possible, the same trademark masterbatch, color masterbatch; for the masterbatch, we must carry out sampling test before the batch production, both with the previous correction, Also in this comparison, if the color difference is not large, it can be considered qualified, as the batch color master has a slight color difference, the color master can be mixed from the head and then used to reduce the color difference formed by the uneven mixing of the color master. In addition, we also need to focus on the thermal stability of the resin and color masterbatch. For the poor thermal stability, we recommend that the manufacturer exchange.
3, reduce the impact of barrel temperature on chromatic aberration
In production, it is often encountered that a heating coil is damaged or the heating control part is out of control, and the temperature of the barrel is drastically changed and then the color difference occurs. The color difference caused by such reasons is easy to determine. Generally, the heating ring damages the color difference and the plasticization is uneven, and the heating control part is out of control. The long burning is often accompanied by product spot, severe discoloration and even coking. Therefore, in the production, it is necessary to frequently check the heating part, and find that the heating part is damaged or out of control, and replace and repair in time to reduce the probability of such chromatic aberration.
4, reduce the impact of the injection molding process adjustment
When the non-color difference reason needs to adjust the injection molding process parameters, the injection temperature, back pressure, injection cycle and color masterbatch addition amount should not be changed as much as possible. At the same time of adjustment, it is necessary to investigate the influence of the process parameter change on the color. If the color difference is found, it should be adjusted in time. Try to avoid using high injection speed, high back pressure and other injection molding processes that cause strong shearing effects, and avoid chromatic aberration caused by partial overheating or thermal differentiation. Strictly control the temperature of each heating section of the barrel, especially the nozzle and the heating part next to the nozzle.
5, grasp the influence of barrel temperature and color masterbatch on the color change of screw products of injection molding machine
It is also necessary to know the tendency of the color of the product to change with the temperature and the amount of the masterbatch before performing the color difference adjustment. Different color masterbatch varies with the temperature or color masterbatch of the product, and the color change rules of the product are different. The color change process can be used to determine the change rules. Unless the rules for changing the color of the masterbatch are known, it is impossible to quickly adjust the color difference.