How to control the color difference of products in the process of plastic mold processing

The color difference of products in plastic mold processing plant is a common defect in injection molding. Due to different colors of matching parts, it is not uncommon for injection molding machines to be abandoned in batches. There are many factors affecting color difference, such as material resin, color masterbatch, mixing of Color Masterbatch, injection molding products, injection molding machine, mold, etc, Therefore, the color difference control skill is recognized as one of the more difficult skills in injection molding. Next, we will introduce in detail

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

In order to select the injection molding machine with appropriate capacity for the main product of plastic mold processing, assume that the injection molding machine has the title of material dead angle, and replace the equipment. As for the color difference formed by the mold pouring system and exhaust groove, it can be treated by the repair mold of the corresponding part of the mold. It is necessary to deal with the injection molding machine and mold title first before organizing the production, so as to reduce the complexity of the title

Therefore, especially in the production of light color products, we can not ignore the significant influence of the thermal stability of the material resin on the glorious shake of the products. In view of the fact that most injection molding manufacturers do not produce plastic masterbatch or color masterbatch, so, when producing light color products, we should not ignore the significant influence of the thermal stability of the material resin on the glorious shake of the products, The focus of attention can be placed on production management and raw material inspection, that is, to strengthen the inspection of raw materials into the warehouse; in the production of the same product, the same manufacturer, the same trademark masterbatch and color masterbatch should be selected as far as possible; as for the color masterbatch, we should carry out sampling and color test before mass production, which should be corrected with the previous time and compared with this time, assuming that the color difference is not big and can be regarded as qualified, It seems that the batch masterbatch has a slight color difference. We can mix the masterbatch from the beginning and then use it again to reduce the color difference formed by the uneven mixing of the masterbatch itself. Together, we also need to check the thermal stability of the material resin and the color masterbatch. As for the unstable thermal stability, we advocate manufacturers to exchange with each other

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

When the masterbatch is mechanically mixed with the masterbatch, the color masterbatch is separated from the masterbatch and easily adsorbed on the hopper wall due to electrostatic effect when the masterbatch and color masterbatch are mechanically mixed and sent to the hopper through the lower suction, which will inevitably lead to the change of masterbatch quantity in the injection molding cycle, At present, many companies choose feeder to add color masterbatch, which saves a lot of manpower and provides great assistance for color difference control. However, many companies do not use it properly, The results are often not satisfactory. The amount of Color Masterbatch added by the feeder at a fixed speed depends on the plasticizing time, which itself is vacillating, sometimes even relatively large. Therefore, in order to ensure a stable feeding amount, it is necessary to fix the feeding time of the feeder and set the timing to be less than the plasticizing time, It may be due to the material particles accumulated in the screw of the feeder, which may cause the feeding machine to stop running, so it needs to be sorted out regularly

3. The influence of temperature reduction on color difference

In the production of plastic mold processing plant, it is often encountered that a heating ring is damaged and invalid, or the heating control part is out of control for a long time, resulting in drastic change of barrel temperature, and then color difference occurs, In order to reduce the probability of such color difference, it is necessary to check the heating part frequently in production, and replace and repair the heating part when it is damaged or out of control

4. Reduce the influence of injection molding process adjustment

When it is necessary to adjust the injection molding process parameters for non color difference reasons, the injection temperature, back pressure, injection cycle and masterbatch addition amount shall not be changed as far as possible. In addition, the influence of process parameter changes on glory shall be investigated. If color difference is found, timely adjustment shall be made. Injection molding process with strong shear effect caused by high injection speed and high back pressure shall be avoided as far as possible, Avoid color difference caused by 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 product color change

Before adjusting the color difference, it is also necessary to know the trend of product color change with temperature and masterbatch quantity. The color change rules of different color masterbatch are different with the change of production temperature or masterbatch quantity. The change rules can be confirmed through color test process. Unless the change rules of color master color are known, it is impossible to adjust the color difference quickly, Especially in the selection of new color masterbatch production color

To sum up, if you have any questions about the above questions, please contact us, we will have professional staff to answer for you