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How to control the color difference of the screw of injection molding machine
AddDate:2018-05-02 From:Xielong

Injection molding machine screw material requirements are many, we have also introduced before. The color difference is a common defect in the screw of the injection molding machine. There are many factors affecting the color difference, involving the mixture of the material resin, masterbatch, masterbatch, injection molding process, and injection molding machine. So how to control the injection molding machine screw product color difference? This issue has been the focus of most industries. Next we discuss together!


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


To select injection molding machines with proper injection molding capacity, it is best to replace the equipment if there is a material dead angle in the injection molding machine screws. With regard to the color difference formed by the mold casting system, the exhaust groove, etc., it can be handled by the repair mold of the corresponding part of the mold. It is necessary to first deal with injection molding machine and mold problems to be able to organize production to reduce the complexity of the problem.


2. Elimination of the influence of resin and masterbatch


Controlling raw materials is the key to completely solving the color difference. Therefore, in particular, when light-colored products are produced, the thermal stability of the resin cannot be neglected to have a significant effect on the fluctuation of the color of the products. Since most injection molding manufacturers do not produce plastic masterbatch or masterbatch themselves, the focus of attention 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 of the same manufacturer if possible, the same trademark masterbatch, masterbatch production; on the masterbatch, we have to conduct sampling test before the batch production, both with the previous correction, Also in this comparison, if the color is not the same, can be considered qualified, as the color masterbatch has a slight color difference, the masterbatch can be used after mixing from scratch to reduce the color difference formed by the masterbatch itself. In addition, we also need to focus on checking the thermal stability of the material resin and masterbatch. We recommend that the manufacturers perform the replacement when the heat stability is not good.


3. reduce the cylinder temperature on the color difference


In the production, it is often encountered that a certain heating coil is damaged or failure, or the heating control part is out of control and burns to form a rapid change in the temperature of the cartridge and then a color difference occurs. The color difference caused by this kind of reason is very easy to determine. In general, heating coil failure and color difference occur at the same time with the phenomena of uneven plasticization, and the uncontrolled burning of heating control part is often accompanied by product air spot, serious discoloration and even coking phenomenon. Therefore, in the production, it is often necessary to look at the heating part and find that the heating part is replaced or repaired in time when it is damaged or out of control, so as to reduce the occurrence of this type of color difference.


4. reduce the impact of injection molding process adjustment


Non-chromatism causes need to adjust the injection molding process parameters, as far as possible without changing the injection temperature, back pressure, injection cycle and the amount of masterbatch added, in the adjustment also need to investigate changes in process parameters on the impact of color, such as color differences should be promptly adjusted. As far as possible, avoid the use of high injection speed, high back pressure and other injection molding process that causes strong shearing effect, and avoid the color difference formed due to partial overheating or thermal differentiation. The temperature of each heating section of the cartridge is strictly controlled, in particular the nozzle and the heating portion immediately adjacent to the nozzle.


5. master cylinder temperature, color masterbatch injection molding machine screw product color changes affect


It is also necessary to know the trend of product color change with temperature and color masterbatch before performing color difference adjustment. Different color masters change with the production of temperature or color masterbatch, their product color change rules are different. It can be determined by the trial process. Unless one knows the rules for changing the color of the masterbatch, it is impossible to quickly adjust the color difference.

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