How to control the color difference of screw products of injection molding machine

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

It is necessary to select an injection molding machine with the appropriate capacity of the main Parallel twin screw barrel product. If the screw of the injection molding machine has problems such as material dead ends, it is best to replace the equipment. Regarding the chromatic aberration caused by the casting system of the mold, the exhaust groove, etc., it can be dealt with by the repair mold of the corresponding part of the mold. It is necessary to deal with the injection molding machine and mold problems first to organize production to reduce the complexity of the problem.

rubber plunger rod

2. Eliminate the influence of raw resin and color masterbatch

Controlling raw materials is the key to completely solving chromatic aberration. Therefore, especially in the production of light-colored products, the significant influence of the thermal stability of the raw resin on the color fluctuation of the product cannot be ignored. Given that most injection molding manufacturers do not produce plastic masterbatches or color masterbatches themselves, attention can be focused on production management and raw material inspection.

That is to strengthen the inspection of raw materials in storage; in production, the same product should be produced by the same manufacturer, the same trademark masterbatch, and color masterbatch as much as possible; regarding the color masterbatch, we must conduct random inspection and color testing before mass production. It will be compared in this time. If the color difference is not big, it can be considered qualified. Just like a batch of color masterbatch has slight color difference, the color masterbatch can be mixed from the beginning and then used to reduce the color difference caused by uneven mixing of the color masterbatch itself. In addition, we also need to focus on checking the thermal stability of the raw resin and color masterbatch. For those with poor thermal stability, we recommend that the manufacturer replace them.

3. Reduce the influence of barrel temperature on chromatic aberration

In production, it is often encountered that a heating ring is damaged and failed, or the heating control part is out of control and long-fired, resulting in a drastic change in the barrel temperature and then a color difference. The chromatic aberration caused by such reasons is easy to determine. Generally, when the heating ring is damaged and fails, the chromatic aberration will be accompanied by the phenomenon of uneven plasticization, and the uncontrolled long-burning of the heating control part is often accompanied by product gas spots, severe discoloration and even coking. Therefore, it is necessary to check the heating part frequently in 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 chromatic aberration.

4. Reduce the influence of injection molding process adjustment

When the injection process parameters need to be adjusted for reasons other than color difference, the injection temperature, back pressure, injection cycle and the amount of color masterbatch added should not be changed as much as possible. During the adjustment, it is also necessary to investigate the effect of process parameter changes on the color and luster. If color difference is found, it should be adjusted in time. As far as possible, avoid the use of high injection speed, high back pressure and other injection molding processes that cause strong shearing effects, and avoid chromatic aberration caused by some factors such as overheating or thermal differentiation. Strictly control the temperature of each heating section of the barrel, especially the nozzle and the heating part close to the nozzle.

5. Master the influence of barrel temperature and color masterbatch on the color change of injection molding machine screw products

Before adjusting the color difference, it is also necessary to know the trend of product color change with temperature and color masterbatch. Different color masterbatches vary with the production temperature or color masterbatch volume, and the rules for changing the color of their products are different. The change rules can be determined through the color test process. Unless the rules for changing the master color are known, it is impossible to adjust the color difference quickly.