There are many reasons for the flow marks on the surface of rubber products. The following are some of the main reasons:
1. The mixed rubber has poor fluidity and excessive viscosity.
2. The mold temperature is too low, resulting in reduced fluidity of the rubber.
3. Poor exhaust.
4. Excessive use of coating powder and release agent.
5. The raw materials of rubber products, such as synthetic styrene-butadiene rubber and natural rubber, contain more impurities. These impurities are exposed during the processing, resulting in flow marks.
6. The raw material formula design is unreasonable, such as uneven dispersion and insufficient vulcanization, which makes the rubber surface sticky and forced to be squeezed during the subsequent processing, leaving marks.
7. During vulcanization, the vulcanized material turns yellow during the vulcanization yellowing process, resulting in obvious flow marks on the rubber surface.
8. During the mixing process, the compounding agent is unevenly dispersed or the proportion of the compounding agent is too high, resulting in obvious flow marks on the rubber surface.
9. During the extrusion process, the extrusion speed is too fast or the extrusion temperature is too high, resulting in obvious flow marks on the rubber surface.
10. During the vulcanization process, the vulcanization temperature is too high or the vulcanization time is too long, resulting in obvious flow marks on the rubber surface.
11. The uneven thickness of rubber products can also cause flow marks.
12. The unreasonable mold design of rubber products, such as gates, mold structures, etc., can also cause flow marks.
13. During the processing of rubber products, defects such as impurities or bubbles are exposed, resulting in flow marks.
14. The vulcanization formula design of rubber products is unreasonable, such as insufficient vulcanization time, too low vulcanization temperature, etc., resulting in insufficient rubber vulcanization and flow marks.
