Any plastic injection mold manufacturer that needs frequent color changes will consider using color change technology. If the high-volume hot runner system does not have a quick color change function, it will increase the cost of thousands of dollars every year. According to the number of such injection molds, the annual cost increase can reach tens of thousands of dollars or more.
By minimizing the number of color-changing injection molding, eliminating the material’s residual dead zone, rationalizing the flow path size, and other methods, the pressure drop is minimized and the material turnover rate is highest, thereby achieving efficient and fast filling.
Then, how to change the color on hot runner?
Non-needle valve hot runner system color change procedure:
- The system has been started and is processing materials of a certain color;
- Move the barrel backward, clean and add new color materials;
- Increase the temperature of the hot runner system in all areas to the working temperature of 30℃~40F/16℃~22℃
- 10 to 15 injections;
- Move the injection mold unit backward and turn off all heating elements on the hot runner system;
- Allow the hot runner system to cool. In this way, the old material can be glued off the wall of the flow channel, so that the new and old colors can be mixed;
- Start the hot runner system and heat to the process temperature
- Move back to the barrel
- Increase the injection molding speed and continue casting until the color becomes acceptable;
- Continue to adjust the process and reset the hot runner system temperature and injection molding speed back to normal.
Precautions
Some plastics can release harmful gases to humans. Please follow the recommendations of plastic suppliers, refer to their material safety data sheets, and ensure that the injection molding work area is well-ventilated.
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