Factors Affecting Color Instability in PVC Injection Molding

July 24, 2017

Injection molding, sometimes appear a few days to change the color, or even within a day there are several color deviation of the situation. There are a number of factors that contribute to the color instability, and the following lists some of the major factors that can lead to color instability in order to improve the control at the time of production.

 

 

 

1.The temperature of the injection molding machine is unstable.The color will be unstable when the tempreture is unstable. It is a major factor in the need for priority inspection.

 

2.Production cycle is unstable. If the machine stop indirectly,  back pressure adjustment caused by excessive running temperature.And it will make the color change.

 

3. Mixers do not meet the mixing process requirements of mixed toner and raw materials.Such as mixing time is insufficient, the feeding method or order is not equal to lead to uneven toner, which is also to focus on inspection.

 

4. The temperature of the baking material is too high or too long. Each of the raw materials and pigments has its own range of baking temperature and time if it is seriously out of this range,  the color of the injection molded parts will be changed. If the feeding time is unstable,then by the temperature of the more obvious color will appear unstable, such as the color of fluorescent materials or light-colored injection parts. So for the temperature-sensitive plastic, it is best not to baked material or to use the end of the temperature baked material.It is best to baked the material first and then mixed.

 

5. In the baking hopper, due to the impact of hot air, the toner appears local concentration, and resulting in more and more color, need to pitting more fruit injection of the pits will appear too much. At this time, it need to increase the number of diffusion oil, so that the toner firmly stick to the raw materials.

 

6. Raw material humidity is too large, resulting in toner bonding can not be spread.

 

7.Toner with not accurate. Each batch of toner has a large deviation in the amount of each element, making it possible to produce a color deviation when using a new batch of pigments.

 

8. When the amount of water back to the amount of time for less, which impact on the light-colored injection of a larger.

 

9.The grade of the raw material is inconsistent. As the color of each raw material is different, resulting in the same color of plastic injection molding will be different. Sometimes the same supplier, while lot number is different, the background will be some deviation, so the color deviation of high demand products, and even to control the quality of each batch of incoming material is consistent.

 

10.The toner quality is too bad, not heat, or use the wrong, inappropriate for the use of toner materials, will make the color instability.

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